【作者】 李碧琼；

【导师】 陈定方； 张雨；

【作者基本信息】 武汉理工大学 ， 机械设计及理论， 2006， 博士

【摘要】 符号时间序列分析是从符号动力学理论、混沌时间序列分析和信息理论发展起来的一种分析方法。其实质是对时间序列值符号化。数据符号化的基本思想就是在几个可能值上对时间序列进行离散化，把许多可能值的数据序列变换为仅有几个互不相同值的符号序列。这是一个“粗粒化”(Coarse-grained)过程。这一过程能够捕获大尺度的特征，从而降低动力学噪声和测量噪声的影响。随着人们环保意识的加强，世界各国排放法规的要求越来越苛刻。在城市道路行驶中，汽油机相当长的时间工作于起动、加速以及减速等瞬态工况，燃油供给和空气供给的速率均在瞬时变化，有害排放物的某些成分，如HC将明显变化，因此在稳态工况下获得的排放参数并不能代表汽油机的实际排放水平。国内、外的一些研究机构目前正在探寻实时动态检测汽油机排放的方法，国内比国外的起步更晚，因此研究瞬态过程的排放及其测试技术具有重要意义。随着世界能源危机和环境污染问题的日趋严重，车用发动机柴油化已成为当今汽车行业不可阻挡的发展趋势，与汽油发动机相比，柴油机具有优良的燃油经济性能和改进潜力很大的排放性能。与汽油机相比，柴油机的颗粒物和氮氧化物排放相对较高，这也是柴油机技术一直在致力解决的问题。但柴油机有许多固有的优势：柴油供应充足，加油站等基础设施比较完备；柴油机良好的燃油经济性，而且技术开发所需的费用相对较低。无论对轿车还是重型货车，柴油机都是一种理想的动力。目前还有一种生物柴油，它与普通柴油非常接近，但产生的二氧化碳排放量更低。柴油机工作时，由于燃烧引起的气缸内压力周期性的变化以及运动机件惯性力的周期性变化，使柴油机机体、气缸盖以及与它们连接的所有部件产生振动。通过实验，本文得到了两种类型柴油机在不同工况下的机身振动加速度信号，它们是典型的瞬态信号。本文对柴油机机身振动数据进行符号时间序列分析，提取有用的特征参数。本论文考虑国内大多数研究机构不具备实时瞬态排放测试的仪器设备这一实际情况，采用间接测量方法，搭建间接测试系统实时采集瞬态过程的排放数据，用符号时间序列方法分析瞬态排放数据，提取瞬态排放的特征，主要的研究内容如下：(1)本文引入了符号时间序列的理论，即单峰映射的符号序列、揉序列和允字条件、单峰图和揉理论，描述了具有混沌吸引子的三维系统是怎样被简化为一维单峰图的；描述了数据符号化的基本过程，即符号时间序列分析方法，符号化的两种方案，符号树以及符号序列统计量，符号序列编码，符号序列直方图，相关参数的选择，符号时间序列流程图等。(2)分析汽油机汽车在城市道路行驶的状况，确定影响城市大气质量的主要瞬态工况，描述了国内外汽油汽车排放研究现状，汽油机瞬态工况的概念及其分类，汽油机瞬态工况的设定，并讨论瞬态工况下的排放特性。(3)根据现行的法规及本研究课题目前所具备的试验条件制定试验大纲，搭建瞬态排放间接测试系统，以及具体的实验方法，即冷起动实验、热怠速实验、加速-滑行组合工况试验，并介绍了测试用主要仪器设备。(4)应用符号时间序列分析方法，结合汽油机瞬态排放数据，用MATLAB编程，得到了富康自由人RPC、北京吉普、吉利等发动机在冷起动、热怠速、加速-滑行组合等工况时CO、HC排放的时间信号及其前向和后向符号序列直方图，计算出信息熵、欧几里得范数等统计量；并对汽油机瞬态排放信号进行了分析和特征提取。(5)简述柴油机的发展现状及特点，描述了柴油机振动信号特征，以及如何用试验的方法获得4135G、190A等两种机型的柴油机机身振动加速度信号的试验。(6)用符号时间序列方法对两种类型柴油机在不同工况下的机身振动加速度信号进行了分析，用MATLAB编程，得到了4135G柴油机第4缸在正常状态、第Ⅰ道气环胶结以及第Ⅰ、Ⅱ道气环胶结的机身振动加速度信号，以及190A柴油机在正常状态、磨损状态、极限状态下的机身振动加速度信号，并且得到了这两种机型的柴油机在上述工况下的前向和后向符号序列直方图，计算出信息熵、欧几里得范数等统计量，从而对4135G柴油机第4缸活塞环胶结程度以及190A柴油机活塞-缸套磨损程度进行了比较。更多还原

【Abstract】 Symbolic time series analysis is a method which originating from symbolic dynamic theory and chaos time series analysis and information theory, its essence is symbolizing time series. The basic ideas of data symbolization is discretizing time-series measurement into a limited set of values. This is "Coarse-grained" process. Symbolization converts continuous-valued time-series measurements into a stream of discrete symbols. This method has the practical effect of producing low-resolution data from high-resolution; only large-scale features are captured, and the effect of dynamic and measurement noise on statistical algorithms are reduced.With the strengthen of people’s environment protection consciousness, the emission regulations of world are becoming stricter and stricter. During the city road running, the gasoline engines frequently run under the conditions of transient operation modes such as cold-start, warm-up, acceleration and deceleration, while the velocity of the supply of fuel and gas also instantaneous change. As some compositions of poisonous emissions would distinctly change, so the emissions results under the conditions of steady operation modes can’t reflect the true results of gasoline engine emissions. At present some research institutions in the world are exploring the ways of real-time dynamic testing, and domestic transient emissions reseach lag the developed countries, so it is extremely important to research exhaust emissions and test technologies of transient process.With the graveness of the world energy sources crisis and circumstance pollute, vehicle’s engine drived by diesel oil become a trend of development of motordom that is impossible to stop. Compared with engine drived by gasoline, diesel engine has good economy performance of fuel and let performance of great ameliorating potential. Compared with gasoline engine, there is exhaust emissions of particulates and oxynitride of diesel engine, this is the problem which we try to solve in diesel engine technology. But diesel engine has many inherent advantages: There is enough diesel supply and self-contained basic establishment such as gas station; Diesel engine has good economy performance of fuel and it need low expense which used for technology exploitation. Diesel engine is a perfect power no matter what for car or for heavy-duty truck. Now there is a biology diesel which adjacence to common diesel but low carbon dioxide exhaust emissions.When diesel engine work, vibration is given birth to between diesel engine economy and cylinder housing and all connection parts as a result of pressure in cylinder change by cycle producing by burning and inertial force of moving economy change by cycle.We obtain two kinds of acceleration signal of economy vibration of two kinds of diesel engine under different working condition, they are typical transient signal. We obtain useful characteristic parameter by analyzing the data of diesel engine economy vibration with symbolic time series method.In this paper the indirect measurement method of transient exhaust emissions is adopted, as there are no advanced equipment that can be used to real-time dynamic test in most reseach institutions. It is practical to build the indirect test system to collect the emissions results, and then analyze results and errors. The research items are follows:(1) This article introduces the theory of symbolic time series, namely symbol sequence of unimodal mapping and knead sequence and word-permit condition as well as unimodal maps and kneading theory, and describes how three dimensional systems that possess a chaotic attractor can be reduced to a one-dimensional unimodal map; It describes the basic process of data symbolization. Namely sombol time series analysis method and two scheme of symbolization as well as symbolic tree and symbol sequence statistics, symbol sequence coding and symbol-sequence histograms and the selection of relational parameter as well as symbol time sequence flow chart are involved.(2) According to the gasoline engine run conditions of city road, the major transient operation modes that affect the level of atmosphere are ensured, and we describe the actual state of exhaust emissions research of gasoline engine of our country and abroad and the concept and classification and the set of gasoline transient working condition, and we discuss the exhaust emission characteristics under transient working condition. (3) Test brief is worked out by current statute and test condition which this subject has in the present, and the gasoline transient emissions indirect test system are built under the existing experimentation conditions. Test method is worked out, namely cold-start test and acceleration-slide test ect. The major instrument and equipment which used for test are introduced.(4) We obtain time signals and forward-time and reverse-time symbol-sequence histograms of CO and HC emission of all kind of gasoline engine such as Fukang RPC and Jeep of Beijing and Jili under cold-start test and acceleration-slide working condition by using symbolic time series analyzed method and by MATLAB, Combining with the data of transient exhaust of gasoline engine, at the same time symbol sequence statistics such as Shannon entropy and Euclidean norm are calculated, then the result of transient exhaust of is analyzed and its characteristic is picked-up.(5) The actual state of development and characteristic are introduced, and characteristic of vibration signal and how to obtain the acceleration signal of economy vibration of two kinds of diesel engine such as 4135G and 190A by test under different working condition are explained.(6) The acceleration signal of economy vibration of two kinds of diesel engine under different working condition are analyzed by symbol time sequence method and by MATLAB, we obtain the acceleration signal of economy vibration of Fourth cylinder body of wear of the first piston ring and adhesive wear of the first and the second piston ring, and we obtain the acceleration signal of economy vibration of 190A under normal state and wear state and limit wear state, at the same time we obtain forward-time and reverse-time symbol-sequence histograms of two kinds of diesel engine under above working condition, as well as Shannon entropy and Euclidean norm of them: so we can compare the degree of the adhesive wear of piston ring of Fourth cylinder body of 4135G and the degree of the wear trouble between piston and cylinder liner of 190A.更多还原