Genetic association of the EGR2 gene with bipolar disorder in Korea

The early growth response gene 2 (EGR2) is located at chromosome 10q21, one of the susceptibility loci in bipolar disorder (BD). EGR2 is involved in cognitive function, myelination, and signal transduction related to neuregulin-ErbB receptor, Bcl-2 family proteins, and brain-derived neurotrophic factor. This study investigated the genetic association of the EGR2 gene with BD and schizophrenia (SPR) in Korea. In 946 subjects (350 healthy controls, 352 patients with BD, and 244 with SPR), nine single nucleotide polymorphisms (SNPs) in the EGR2 gene region were genotyped. Five SNPs showed nominally significant allelic associations with BD (rs2295814, rs61865882, rs10995315, rs2297488, and rs2297489), and the positive associations of all except rs2297488 remained significant after multiple testing correction. Linkage disequilibrium structure analysis revealed two haplotype blocks. Among the common identified haplotypes (frequency > 5%), 'T-G-A-C-T (block 1)' and 'A-A-G-C (block 2)' haplotypes were over-represented, while 'C-G-G-T-T (block 1)' haplotype was under-represented in BD. In contrast, no significant associations were found with SPR. Although an extended analysis with a larger sample size or independent replication is required, these findings suggest a genetic association of EGR2 with BD. Combined with a plausible biological function of EGR2, the EGR2 gene is a possible susceptibility gene in BD.     

Membranes producing nitrogen-enriched combustion air in diesel engines: Assessment via dimensionless numbers

The challenge of reducing nitrogen oxides (NO_X) emissions in diesel engine exhaust gas can be met by the use of nitrogen-enriched air (NEA) for combustion. In this work, the separation performance of membranes producing NEA is simulated and experimentally validated. Retentate nitrogen concentration and stage-cut depend on the membrane properties oxygen–nitrogen selectivity, oxygen permeance and membrane area as well as on the operating parameters, feed pressure, permeate pressure and feed flow rate. This complex dependence is presented using correlations of dimensionless numbers for retentate oxygen mole fractions between 16 and 21 mol%. It is herewith possible to calculate membrane area and compression power loss for any given membrane at any engine load point. The correlations also serve to identify the most suitable membrane and operating parameters when having to meet design criteria, e.g. limited construction space or maximum power loss. In a design example, both membrane area and power demand are calculated for three state-of-the-art membranes at a number of characteristic load points of a medium-duty diesel truck engine.     

四气门汽油机分层EGR的试验研究

针对可以产生较强滚流运动的1.6 L四气门产品汽油机,设计了一套独特的分层废气再循环(EGR)装置。通过废气导入管将废气引到进气阀处,利用缸内气体滚流运动,实现废气与新鲜可燃混合气分层。在发动机台架上通过试验详细地研究该分层EGR装置对汽油机性能和燃烧的影响。试验结果表明,采用该装置后,相比于传统的EGR方式,EGR 率有所增加,在大量降低NOx排放同时,经济性有所改善, CO和HC排放有所降低,燃烧效率提高,但点火时刻应适当提前。     

电控EGR阀综合性能测试系统的研制

电控EGR阀是废气再循环技术中重要部件,主要包括步进电机式、电磁式和直流电机式,目前针对电控EGR阀测试系统研究尚不充分。为了实现对电控EGR阀各项技术指标的测试,研制了一套电控EGR阀综合性能测试系统。系统由驱动单元、控制单元、测试单元组成。驱动单元以电控EGR阀驱动器为驱动核心,控制单元以可编程控制器为控制核心,测试单元由各项指标的测试模块组成。通过对各项技术指标测试工艺流程设计,系统实现了对电控EGR阀流量特性、内漏性能、响应时间和阀内位置感应器性能的自动测试。实验结果表明,该系统稳定可靠,各项参数的机器能力指数Cmk均超过1.67,满足技术要求。系统提供了一种针对电控EGR阀综合性能的测试方案,并成功应用于某企业电控EGR阀生产测试车间。     

废气进口位置对汽油机性能和NOx排放影响的研究

为同时兼顾排放性、经济性和动力性,提高汽油机废气再循环率,提出改变EGR进气方式,将EGR废气通过管路直接通到进气门处的方案。在一台四气门汽油机上对进气门处单侧通废气与中央通废气的方式进行了对比试验。试验结果表明,与中央进气方式的EGR相比,单侧EGR进气方式在降低同样NOx的排放的情况下,具有更高的燃油经济性、动力性和EGR率。另外,单侧EGR不必降低EGR进气温度,即能获得较较好的发动机性能。     

EGR率对生物柴油颗粒纳米结构的影响

为研究同时运用废气再循环(EGR)技术和燃用生物柴油对柴油机排气颗粒纳米结构的影响,分别采集0%,15%,30% EGR率下186F柴油机燃用生物柴油时的排气颗粒,并用激光拉曼光谱仪测得颗粒光谱,使用五带法对一阶拉曼光谱进行拟合,分析拟合曲线参数,计算颗粒微晶尺寸和碳碳键长度。结果表明：EGR率为30%时,生物柴油颗粒光谱的半高宽(FWHM)最大,代表化学异相性最强并且颗粒中的物质种类最多,随着EGR率降低,半高宽逐渐减小;当EGR率从0%升高到30%,I_D/I_G逐渐增大,代表石墨化程度降低,颗粒中的石墨结构减少;同时,I_D1/I_D2从0% EGR率的8左右降低到15%和30% EGR率的4左右,代表EGR率升高,颗粒内部缺陷由空位缺陷向石墨烯边缘缺陷发展;随着EGR率升高,微晶尺寸逐渐减小,碳碳键长度基本不变。     

Role of radicals on MILD combustion inception

The criterion used to define MILD combustion in non-premixed condition is analysed using Direct Numerical Simulation (DNS) of MILD combustion of methane-diluted air established with internal exhaust gas recirculation. The simulations reveal multiple interacting reaction zones in MILD combustion which are extremely different from conventional combustion. Furthermore, DNS deduced S-curves highlight the role of chemically active species. Specifically, the temperature rise is accompanied with an increase in the scalar dissipation rate of mixture fraction, which is quite contrasting to the classical S-curve from the classical flame theories. This observation is explained on a physical basis.     

Particle Tracking Based Method for Evaluation of Cylinder‐to‐Cylinder Distribution of EGR/Blowby

Exhaust Gas Recirculation (EGR) method has already shown its benefits on controlling NO_x emissions in internal combustion engines. An important issue associated with this method is homogeneous cylinder‐to‐cylinder distribution of the recirculating gas. Any maldistribution leads to power reduction and increase of other pollutants, which are strictly limited by recent emission laws. In addition to EGR, these limitations force the engine manufacturers to recycle blowby gases into the cylinders as homogeneous as possible. Since geometrical parameters and injection locations of EGR/blowby have substantial effects on homogenous cylinder‐to‐cylinder distribution of EGR/blowby gases, any developments in identifying the injecting locations with the least EGR/blowby maldistribution are of great practical importance. The existing experimental and numerical methods for evaluating the EGR/blowby maldistribution are based on the injection of air with different temperature or of different gas (mostly CO₂) from the main air stream. However, these methods are time consuming due to the large number of possible injection locations. It has been shown that the most uniform distribution cannot be obtained by just a single injection point; therefore, the study of simultaneous injection points becomes inevitable. Clearly, such a study is practically impossible with the present methods. In this research a new method based on particle tracking is proposed, which greatly reduces the time and effort to find the injection locations with the least maldistribution, especially when multiple injections are considered.     

废气再循环和添加剂对高辛烷值燃料HCCI燃烧的影响

本文对废气再循环(EGR)和十六烷值改进荆-过氧化二叔丁基(DTBP)对高辛烷值燃料HCCI燃烧的影响进行了研究。实验结果表明:辛烷值为90的燃料(RON90)只能在高温高负荷下才能运行HCCI燃烧模式;在其中加入少量的DTBP后,RON90实现HCCI燃烧的工况范围向低温低负荷下大幅度拓展。加入添加剂后,低负荷性能改善的同时,浓混合气的着火时刻可以通过EGR将含添加剂燃料的着火时刻推迟到上止点附近,从而大幅度提高热效率,降低了燃料消耗率。     

Effect of O2 concentration in ambient mixture and multiphase radiation on pollutant formation in ECN spray-A

This study investigates the formation and evolution of soot and NO _X in a high-pressure constant-volume combustion chamber. This work focuses on the effect of multiphase thermal radiation and O₂ dilution in ambient/exhaust gases, sometimes also referred to as exhaust gas recirculation (EGR), qualitatively and quantitatively. The spray-A case (n-dodecane as fuel) from Engine Combustion Network (ECN) is used as the target condition. Two different soot modelling approaches have been considered: a semi-empirical two-equation model and a detailed method of moments with interpolative closure (MOMIC) model. A multiphase photon Monte Carlo (PMC) solver with line-by-line (LBL) spectral data is used to resolve radiative heat transfer. Results show that the effect of radiation on soot is minimal in spray-A. Inclusion of radiation modelling, on the other hand, marginally reduces NO prediction. Both peak soot and NO formation increase with O₂ content in the ambient gas. Oxygen content in ambient gas is also found to have significant effect on soot sizes as the mean soot diameter increases along with considerable widening of the diameter distribution with the increase of O₂ percentage in the ambient gas.