瞬态工况对内燃机燃烧噪声的影响研究

研究了内燃机瞬态工况对燃烧噪声影响机理,开展了内燃机瞬态工况测试技术和测试方法研究,通过对瞬态与稳态过程的缸内压力、缸内压力最大值、压力升高率、压力升高率最大值、压力高频振荡以及气缸压力级等参数在不同频率范围的差异的研究分析,从气体动力载荷和高频压力振荡两方面分析研究瞬态噪声与稳态噪声产生差异的机理.瞬态与稳态工况压力升高率变化趋势与两种工况下燃烧噪声变化趋势基本相似,但在一些工况上存在差异,这是由于受到了缸内压力高频振荡对燃烧噪声影响的结果.结果表明：瞬态与稳态工况燃烧噪声的差异是由压力动力载荷与压力高频振荡共同影响的结果.     

川西致密砂岩气藏新的矿场评价标准和评价方法

文章根据川西致密砂岩气藏的损害特征和现场100多口井的测试资料的统计分析表明,储层表现出自身的损害特点,其常规的矿场评价指标和标准不一定完全适合非常规的致密碎屑岩气藏的情况,针对川西致密砂岩气藏损害特征,提出新的气藏损害的评价标准,同时根据致密砂岩气藏油层损害的要求和评价标准的需要,建立起新的描述裂缝-孔隙性砂岩气藏损害评价的数学模型,该模型在原来裂缝-孔隙性砂岩渗流模型的基础上考虑裂缝与基块之间窜流表皮系数对渗流物影响。将该矿场评价标准和评价方法应用于川西致密砂岩储层的损害评价中取得很好的效果,这不仅对于川西致密砂岩的油层损害评价有现实意义。而且对裂缝-孔隙油气藏的试井解释和损害评价都具有重要的指导意义。     

InP中皮秒快速现象

利用测量瞬态反射谱的方法，探索了掺硫、铁、锌以及非掺杂的ＩｎＰ中载流子寿命，观察到非掺杂ＩｎＰ中载流子寿命最长约６０ｐｓ，掺锌ＩｎＰ中载流子寿命３８ｐｓ居中，掺硫和掺铁的寿命最短约１ｐｓ掺硫、铁和锌的ＩｎＰ中载流子寿命下降，是由于掺杂引入了复合中心，这一结果已被喇曼光谱所证实。     

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.     

MOS结构深能级瞬态谱的测试与分析

叙述了一种采用MOS结构研究半导体深能级陷阱的深能级瞬态谱(DLTS)测试与分析方法。该方法简便易行,适用范围广。通过对n-Al_(0.2)Ga_(0.8)As中深能级的研究表明,MOS结构和p~+-n结构的DLTS结果相同。     

脉冲载荷下柱壳结构响应实验研究

利用电子束及化爆对柱壳模拟结构进行脉冲加载，通过试验研究结构响应规律及结构破坏阈值，对壳体结构响应的基本理论进行了论述和分析；根据电子束及化爆加载实验结果，重点分析了不同结构的破坏阈值；提出了提高柱壳壳体抗脉冲载荷能力的技术途径。     

Disturbance rejection of battery/ultracapacitor hybrid energy sources

This paper contributes an active control strategy to reject disturbances in hybrid energy source systems applied in hybrid electric vehicles. The disturbances include persistent disturbances introduced by engine torque ripples compensation, and transient disturbances caused by transient load power demands. The disturbance rejection is achieved via singular perturbation theory. The original system is a Port-Controlled Hamiltonian (PCH) system, and the controller is designed based on interconnection and damping assignment. Experimental results verify the effectiveness of the disturbance rejection control.     

Study on the thermo-effect of nugget growing in single-phase AC resistance spot welding based on the calculation of dynamic resistance

According to the welding current and electrode voltage detected in resistance spot welding, the dynamic resistance was calculated and the nugget growing thermo-effect in process of nugget forming was studied. The results showed that the process of nugget growth in resistance spot welding can be divided into three stages, which were initial stage, growing stage and stable stage. The welding current provided energy for nugget growth, which showed a high linear relationship with mean dynamic resistance and more prominent polynomial relationship with dynamic resistance heat. The dynamic resistance heat was an important evaluating indicator to the nugget growing thermo-effect, which was closely related to the characteristics of nugget forming. As the dynamic resistance heat was increased, the nugget diameter and tensile shear strength of spot weld were raised and showed a more prominent polynomial relationship. According to the calculation of dynamic resistance heat, these relationships provided a method for the nondestructive test of nugget quality features.     

Efficient computational method for transient EM response of large-loop source over layered earth

Calculations of the ElectroMagnetic （EM） response produced by a large horizontal loop placed over layered medium are rather complex because its integral expression contains the product of two Bessel functions and has a divergent term. In this paper, an improved fast Hankel and Gaver-Stehfest transforms are introduced to solve the strong-oscillation and slow-decay properties of the integrand, where one Bessel function in the product is substituted by a carefully chosen polynomial of high accuracy and the other used as the digital filter coefficients in the convolution integral. Comparisons prove the validity and the efficiency of the proposed method.     

Numerical investigation of the auto-ignition of transient hydrogen injection in supersonic airflow

The auto-ignition process in high Mach number airflow is performed by Large Eddy Simulation. The predictions are in good agreement with experiment. The temporal and spatial analysis of the auto-ignition process are carried out. The results show that the auto-ignition process can be divided into five stages in terms of time sequence, and there are three regions in space at the steady state. It is also found that the maximum mass fraction of HO₂ is one of the best indicators to see whether the scramjet working on high Mach number reaches steady state, and the flame stabilization is dominated by auto-ignition. The heat release rate of different combustion modes is calculated. It reveals that the supersonic combustion mode dominates in all stages and regions, but premixed combustion mode dominates only in transient auto-ignition stage and the auto-ignition region.