Correlation of combustion noise with ignition-timing in an IC engine

ABSTRACT

The need for development of a more efficient IC engine is always on the rise which can be related to oil being a non-renewable resource and its increasing carbon foot print causing global warming. In addition to the CO₂, there are more toxic pollutants such as NOx, CO and HC due to improper combustion. These demands have paved way for development of alternative fuel engines such as bio-diesel, bio-ethanol and hybrids. Still these engines need to optimise their combustion to get the best of both worlds. And for the purpose of optimisation there must be a means to measure and estimate the combustion characteristics. Thus analysing the combustion noise gives some insight into the performance of the engine.     

Cylinder Liner Surface Analysis During SI Engine Break-In

Surface texture of an engine cylinder liner at the top-ring reversal point was observed by using Scanning Electron Microscopy (SEM) and optical microscopy. Experiments were conducted on a single-cylinder spark ignition engine over the engine break-in period. The surface texture of the cylinder liner was observed before and after the break-in test. The changes of surface texture and the wear mechanisms during the engine break-in were analyzed. The primary wear mechanisms were found to be abrasion and plastic deformation.     

Expanding needs for metrological traceability and measurement uncertainty

In our daily life, numerical evaluation of a quantity is normally required not only for scientific decision but also for judgment of products. Under the Metre Convention, ideal system of the International System of units (SI) is globally recognized and utilized in many fields of science and technology [1]. Some documented standards such as International Vocabulary of Metrology (VIM) [2], and Guide to the expression of Uncertainty in Measurement (GUM) [3] are edited and published by the Joint Committee for Guides in Metrology (JCGM) and commonly introduced in the fields of metrology, science and conformity assessment in connection with ISO/IEC 17025. This paper describes the recent situation in measurement science, and how to obtain a reliable measurement result using the expression of metrological traceability together with measurement uncertainty. In the paper, a response to Prof. Ludwik Finkelstein’s message for ‘challenges and problems to future advancement in measurement science’ is also reported.     

SOC设计SI分析优化方法研究

基于集成电路规模与设计工艺不断发展的现状,SI问题日益突出和严重。系统介绍了SOC设计SI的概念、分类及产生基理,根据电路工程设计经验,重点阐述了在SOC设计SI的设计、优化、分析方法,介绍了利用EDA设计工具在芯片设计过程中对SI进行阻止、优化、分析的流程及方法,并对各种设计优化方法进行了利弊的对比分析,对芯片设计提供了很好的指导,结合EDA工具及合理的设计流程方法能够有效的保证芯片设计的良率和性能。     

发动机非常规排放物甲醛的检测与分析

以Flyer M-TCE汽油发动机为对象,以环境空气中甲醛测定方法为基础,采用便携式现场甲醛测定仪,分别进行了93号汽油、甲醇汽油（M15、M25、M85）、乙醇汽油（E10、E25）在一定工况下的非常规排放物———甲醛的检测。结果表明,发动机燃用汽油和醇燃料时,排气中都会产生醛类排放物,且随着混合燃料中的醇含量增加,排气中醛类排放物也相应增加;同一种燃料进行测试时,甲醛排放随着功率的增加呈先增大后减小的趋势;双三元催化器对甲醛有一定的催化作用。通过台架实验得到大量醇类燃料发动机甲醛排放数据,为今后开发醇类燃料汽车燃烧系统及制订排放标准提供依据。     

Influence of the oxidative/reductive treatments on Pt/CeO2 catalyst for hydrogen iodide decomposition in sulfur–iodine cycle

A Pt/CeO₂ catalyst was prepared by sol–gel method. The as-received sample was successively oxidized, reduced and re-oxidized. The samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and hydrogen iodide (HI) catalytic decomposition activity evaluation for the sulfur–iodine cycle. The oxidative/reductive atmosphere affected the structure and performance of the catalyst by the strong metal-support interaction (SMSI). It was suggested that a migration of Ce⁴⁺ from the bulk to the surface occurred during the reductive treatment. The diffusion process was reversed when the atmosphere was changed to an oxidative one. The decoration or encapsulation of Pt by ceria support changed with the atmosphere, and affected the activity of the catalyst. At temperature below 400 °C, the reduced sample exhibited the best activity. After then the activity of the reduced and re-oxidized samples tends to be the similar, but still better than the as-received and oxidized samples. The surface and interfacial Pt⁰ sites were both considered as the effective factors. Models were constructed to describe the diffusion of Ce⁴⁺ and oxygen vacancies as well as the possible shell-core structure of Pt crystallites and the decoration/encapsulation by ceria support.     

计算机视觉技术在发动机缺陷检测系统中的应用

利用计算机视觉技术及相应的机械伺服系统,对汽车发动机缸孔表面缺陷进行检测,其主要解决的问题是:缸孔图象区域分割,二值化图象阈值的选取以及目标缺陷的确定.针对以上问题,采用直方图均值适应法选取二值化阈值,对识别出的缺陷进行标定,并通过拟合方程得到缺陷的实际尺寸并最终确定出目标缺陷.实验结果表明此方法克服了传统检测方法的不足,是一种准确性和自动化程度较高的检测方法.     

Ceria as a catalyst for hydrogen iodide decomposition in sulfur–iodine cycle for hydrogen production

In this work, ceria (CeO₂) prepared with different methods and at various calcination temperatures have been tested to evaluate their effect on hydrogen iodide (HI) decomposition in sulfur–iodine (SI) cycle at various temperatures. The CeO₂ catalysts' strongly enhance the HI decomposition by comparison with blank test, especially gel CeO₂ 300. TG–FTIR, BET, XRD, TEM and TPR were performed for catalysts' characterization. The results show that the CeO₂ catalyst synthesized by citric-aided sol–gel method and calcined at low temperature (<500 °C) shows more lattice defects, smaller crystallites, larger surface area and better reducibility. Oxygen can promote the significantly rapid surface reaction, but simultaneously consume hydrogen species (H) contained in HI. Lattice defects, especially the reduced surface sites, i.e., Ce³⁺ and oxygen vacancy, play the dominant role in surface reactions of HI decomposition. A new reaction mechanism for HI catalytic decomposition over CeO₂ catalyst is proposed.     

线性规划应用于工程网络图中时间—费用优化

利用线性规划模型对工程网络图中的时间-费用优化问题进行了研究,并与网络优化法进行了比较,得到了线性规划优于网络优化法的结果。     

H.264/AVC中SP帧技术的应用研究

SP帧技术是H.264/AVC新视频标准中定义的新类型帧技术。其主要特点是:即使使用不同的参考帧也能预测恢复出相同的SP帧,因而SP帧可以在流间切换、拼接、随机插入以及差错控制等应用中取代I帧实现相应功能。文章在介绍基于SP帧技术各种具体应用的基础上,通过大量仿真试验对SP帧进行了各种情况下的研究,并从中获得具有指导性的结论。