Research On Relevant Theory And Methods For Urban Environmental Noise Problems And Their Application

With the acceleration of worldwide urbanization course, the rapid expansion of city scales and the continuous development of city construction, problems of urban environmental noise are becoming more and more serious. They have brought increasingly severe influence on people's working and living. And these problems have gradually become hot spots that arouse extensive attention. Taking urban environmental noise in Dalian as engineering background, this dissertation studies computational intelligence, comprehensive evaluation and technique of acoustic vibration measurement & default diagnosis as well as their application to the relevant problems of urban environmental noise. The problems of urban environmental noise involve abundant contents and relate to many factors. This dissertation puts study emphases on optimization of the noise measurement points, comprehensive evaluation of noise quality and traffic noise control. Theoretically, this subject concerns to mechanical engineering, environmental science, acoustics, computer science, system & control engineering. And it can be ascribed as the frontier fundamental and applied research of cross-discipline subject. In practice, this subject has extensive engineering application prospects, such as monitoring and evaluation of water and air pollution in the field of environmental protection as well as the delivery test of noise quality for various vehicle gearboxes and mechanical drive systems. Meanwhile, the proposed computational intelligence algorithm can also be applied to many optimization problems of complex engineering systems. Altogether, this subject is of great importance and urgency in terms of theory and practice. But it is still far from being solved satisfactorily.The optimization problem of measurement points of urban environmental noise can be boiled down to a discrete 0-1 programming problem. Since it belongs to NPC problems, it's hard to solve this problem very well; Urban noise quality evaluation belongs to comprehensive evaluation problems in system engineering, which possesses the characteristic of multiple indices, multi-layers, strong correlation, etc. Only by qualitative evaluation of relevant experts, it is rather difficult to meet the requirements of scientificity and objectivity for complex engineering systems; Delivery test of noise quality and relevant fault diagnosis for automobile gearboxes is one of the important aspects of urban traffic noise control. To avoid the influence of workshop background noise, the common method of testing whether the noise generated by gearboxes exceeds the delivery test standard or not is to measure the noise sound pressure level by sound level meter in anechoic chambers. But this method is rather time-consuming and laborious as well as it's difficult to realize the measurement directly on production line. As above stated, it's clear that there exist considerable difficulty and complexity to solvethese problems. According to the state of our nation, this dissertation carries out the following research works for them.1. Research engineering background and significance are explained. Moreover, the corresponding solutions and typical research works at home and abroad for relevant problems in the field of urban environmental noise are surveyed. On the basis of them, the research methods and solution strategies of this dissertation are made clear further.2. A parallel hybrid PSO immune algorithm (PHPSO-IA) is proposed based on parallel genetic algorithm (PGA) in this dissertation. To overcome the two main defects, i.e. premature convergence and slow convergence rate, of the traditional parallel genetic algorithm, PHPSO-IA makes a series of improvements on PGA as follows, (a) Subpopulations are classified as several types according to modified crossover and mutation operators and all types of subpopulations evolve parallelly.(b) In accordance with the characteristics of different types of subpopulations, different types of individual PSO update operators are introduced. And it aims at making full use of the fast convergence property of particle swarm optimization.(c) Introducing immunity theory into PHPSO-IA has double functions. One is that proposed immune selector based on adjustable geometric-progression rank-based selection can prevent the algorithm from premature effectively. The other is that convergence rate can be accelerated by individual migration strategy between subpopulations based on imitation of immune memory mechanism and inoculation procedure, (d) The chaos sequence search for superior individuals can improve local searching performance of the hybrid algorithm considerably. PHPSO-IA is a universal hybrid computational intelligence algorithm. It contains continuous and 0-1 discrete versions in this dissertation and can be adopted to solve these two kinds of problems. Examples of typical function optimization and knapsack problems show that PHPSO-IA is feasible and effective. In view of lack of consideration for non-uniform distribution of real acoustic field when locating measurement points by traditional noise measuring method with equal grids, the idea of locating points by the method with unequal grids are given based on the strategy of element partition in finite element analysis (FEA). Moreover, on the basis of it, PHPSO-IA is adopted to solve the optimization problems of measurement points in the field of urban environmental noise. The results are satisfactory. It can greatly reduce the consumption of manpower and material resources during the course of measuring noise in future and open a gate for realizing automatic monitoring and evaluation of urban environmental noise.3. Multilevel modified set pair analysis method based on C/S & B/S mixed mode is presented. And it is applied to comprehensive evaluation for urban environmental noise quality. First of all, to overcome the defect that it's not convenient to decide the concrete pollution class when traditional set pair analysis(SPA) is applied to the field of environmental quality evaluation, the method of modified set pair analysis (MSPA) as well as its evaluation criteria based on integrated connection degree are proposed. Taking the evaluation of urban environmental noise quality in Dalian as example, it verifies that the multilevel MSPA is reasonable, effective and practical by comparing it with multilevel fuzzy comprehensive evaluation, whose weight vectors are both given by AHP. Evaluation results by above two methods are consistent and coincide with objective reality. Moreover, multilevel MSPA based on C/S & B/S mixed mode is presented further. It possesses the characteristics of flexibility, convenience and maintainability. As well as, it can realize the resource and information sharing for relevant personnel at different geographic positions. The above network-based multilevel MSPA is beneficial to making an evaluation more objective and accurate as well as raising relevant working efficiency. To contribute to actual engineering applications, making the relevant algorithms and methods proposed in this dissertation as well as SoundPLAN and Maplnfo integrated, the overall design planning and modular framework structure of the evaluation software system for urban environmental noise are presented. And the corresponding software system is programmed. All of this work benefits promoting research progress of relevant theory and methods in the field of comprehensive evaluation of urban environmental noise.4. Traffic noise is the foremost source of urban environmental noise. And the vehicle noise is the key factor of it. From the point of view of controlling the noise quality of automobile gearboxes before leaving factories, a new on-line noise vibration measurement method and the fault diagnosis method for automobile gearboxes exceeding noise standard are proposed. The former can realize the delivery test of gearboxes' noise on production line. The derived relevant formula and the concrete vibration measurement procedure are given, which can effectively prevent from being affected by the background noise and obtain the sound pressure level of gearboxes' noise on production line by testing the vibration acceleration signals of boxes. The latter is a fault diagnosis method based on local wave theory and octave analysis. The local wave method can decompose complex signals into finite local wave components and make them separate in time-frequency coordinate system. It also can avoid the mutual influence of sidebands of different frequencies. The octave analysis can further calculate the corresponding frequency-band sound pressure levels of components and find out the frequency within a frequency band that radiates maximum noise. Thus, the fault source can be final decided. The abovementioned two methods are combined into a complete flowchart. It makes the delivery test of gearbox noise more convenient and effective. This work is beneficial to updating gearbox delivery quality and improving the performance of whole vehicle. Therefore, it contributes tocontrolling traffic noise and even total urban environmental noise effectively.This subject is a collaborative research project of Institute of Vibration Engineering of Dalian University of Technology and Dalian Environment Monitoring Center. And it is financially supported by the National Natural Science Foundation of China (No. 50475155). Altogether, it not only benefits the development of science and technology in related fields theoretically, but also has great economic returns and social benefits. And it can be spread through and applied to various relevant problems stated-above.