The Symbolization Analyzing Of Transient Signal And Its Engineering Application

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.