Effect of the fuel injection strategy on the combustion process in a PFI boosted spark-ignition engine

In this paper, the effect of different fuel injection strategies on the combustion process was investigated in a boosted port fuel injection spark-ignition engine. The experiments were performed on a partially transparent single-cylinder engine, equipped with a four-valve head and boost device. Single and double fuel injection strategies were tested in the open-valve condition. Moreover, two fuel injection pressures were considered. Optical techniques based on 2D-digital imaging were used to follow the flame propagation in the combustion chamber. In particular, the diffusion-controlled flames near valves and on cylinder walls due to the fuel film burning were studied. Two-colour pyrometry was employed to measure soot concentration. In-cylinder optical investigations were correlated to the engine parameters and to the exhaust emissions.     

Uniformity of deep levels in semi-insulating InP obtained by multiple-step wafer annealing

The uniformity of deep levels in semi-insulating InP wafers, which have been obtained by multiple-step wafer annealing under phosphorus vapor pressure, was studied using the thermally stimulated current (TSC) and photoluminescence (PL) methods. Only three traps related to Fe, T₀ (ionization energy E_i=0.19 eV), T₁ (0.25 eV), and T₂ (0.33 eV), probably forming complex defects, were observed in the wafer and they exhibited a relatively uniform distribution. PL spectra relating to phosphorus vacancies observed in some regions of the wafer are correlated with a small TSC signal having an ionization energy of 0.43 eV.     

夏利2000发动机稀薄燃烧电控系统的研制与应用

研制了一套适用于稀燃汽油机的电子控制系统.系统控制单元ECU参考Siemens公司电控系统设计方案,以C167系列单片机作为微处理器,对发动机的控制采用集中控制,可以实现高级轿车发动机ECU所有功能.本电子控制系统主要应用于丰田8A16气门EFI发动机进行稀燃匹配实验.实验结果表明,该系统基本达到了对控制的速度和精度的要求,得到的稀燃节油和降低排放效果十分明显;且系统性能可靠、抗干扰性强、功能完善、操作方便.     

As~+、Si~+双注入GaAs瞬态退火的行为

研究了不同能量、剂量As~+、Si~+双注入于SI GaAs中,As~+注入对注Ss~+有源层的影响.首次给出了双注入样品瞬态退火后有源层的激活率和载流子迁移率,退火前后材料的沟道谱.实验表明,As~+、Si~+双注入样品比Si~+单注入样品在较低退火温度下就能激活Si~+,在适当高温下能得到性能良好的有源层.     

高速通信系统 PCB 的电磁兼容性设计

文中从通信系统的信号完整性设计和电磁兼容性设计的概念讲起,重点描述了某高速通信系统的EMC设计方法。该系统基于CPU、FPGA和DDR的核心架构,有信号频率高、交换容量大、板卡EMI指标严格的设计难点。文中在系统的EMC设计过程中重点考虑了高速信号完整性和电源完整性,有效的突破了该高速PCB设计的关键技术,并搭建了测试平台对板卡的信号完整性、电磁辐射进行了全面测试。经实验证明,文中设计的系统信号完整性与电磁兼容性性能优良,充分满足了设计要求,工作稳定可靠。     

汽油发动机电控系统的应用研究

汽油机电控系统，不仅具备适应发动机各种工况变化的燃油喷射控制功能，还能对电子点火，怠速转速等进行控制。且详细介绍了系统的结构，各功能的控制原理及方法，并给出较理想的试验结果。     

可变滚流与二次喷油对火花点燃式发动机稀燃特性影响的研究

本文研究了可变滚流与二次喷油技术对发动机稀燃特性的影响。研究发现:1)在三种滚流比情况下,发动机比油耗随二次喷油比例的增加,呈下降趋势,说明在缸内只存在滚流运动的情况下,采用较大比例的二次喷油量可以获得更好的燃油经济性。2)喷油正时明显影响发动机燃油耗,在三种滚流比情况下,最低油耗点所对应的喷油正时按照T1、T2和T3顺序依次提前;负荷较大时,对应的最低油耗点喷油正时也相应有所提前。3)增强进气滚流运动可以改善发动机低速工况条件下的燃油经济性和排放特性,但应避免可变滚流机构对燃油喷注的阻隔作用。     

电控汽油喷射发动机中点火线圈与喷油器的控制

详细分析了电控汽油喷射发动机中点火线圈控制信号与喷油器控制信号的定时关系，提出采用双可编程定时／计数器联动产生控制信号的方法，并对这种方法的控制精度及其优缺点给予分析与评价。     

二冲程汽油机电控燃油喷射系统的试验研究

开发了一种适用于二冲程汽油机的电控喷射系统，对不同喷射方案进行了系统的试验研究，提出了适合于电子控制低压汽油喷射的喷油器位置，喷油开始时间等参数。台架试验结果表明，电控喷射式二冲程汽油机与化油器式二冲程汽油机相比，在燃油经济性和排放指标两方面都有明显的改善。     

火花点火式发动机未燃碳氢形成机理及影响因素的研究

详细阐述了火花点火苣了缸内未燃碳氢排放的主要生成源和形成机理，并测量了不同运转参数火花点火式发动机的碳氢排放。