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Aiming at the multi-dimensional and strong coupling problem of design and manufacturing caused by the high dimensionality of systems and large number of units of complex mechanical products, a module partition method based on spectral clustering algorithm was proposed. The hierarchical decomposition of products was realized based on the function-flow-structure decomposition method, and fuzzy mathematics was used to define the correlation between feature elements. On this basis, the association relation model of product parts based on numerical design structure matrix was constructed. By introducing the spectral clustering algorithm, the component clustering problem was transformed into the optimal division problem of the graph, and the evaluation index of module division based on the average cohesion within the module and the average coupling between the modules was constructed to realize the module division of the products. The results of the examples showed that the method could effectively reduce the complexity of the design and manufacturing of complex mechanical products, and the method was scientifically effective. [ABSTRACT FROM AUTHOR]

Industrial gas appliances have a huge market prospect in boilers and industrial furnaces. In this paper, gas burners and its working process was briefly introduced. Based on EN676, a new test method of natural gas interchangeability was put forward to test industrial appliances' combustion performance. Three typical burners were selected to test the thermal performance when fuelled with 6 kinds of natural gases. The results showed that this method is suitable for interchangeability study of boiler burner, and its reliability was proven. [ABSTRACT FROM AUTHOR]

The AGA Indices method and weaver indices method are typical overseas interchangeability discriminant methods. Under the background of interchangeability of multi-source natural gas in Shanghai, the pipeline gas in lab is used as reference gas, the AGA Indices (IL, IF, IY) and Weaver Indices (JH, JA, JF, JL, JI, JY) of all kinds of substitute gas were calculated. The interchangeability of reference gas and substitute gas was analyzed theoretically and experimentally. Finally, compared tests with the calculation results, analyzed and discussed the domestic applicability of two indices methods. The tests proved AGA Indices method could well predicted interchangeability but did not give the emission index of CO, while Weaver Indices could well predict flame-out, backfire and heat load change but did not accurately reflect yellow flame and CO emission. Therefore, in order to reflect completely the results of interchangeability by pure index methods, it is necessary to analyze the interchangeability combining domestic reality with two indices methods. Nowadays experiment is still an essential way for identifying interchangeability. And gas interchangeability should not be confused with gas classification. [ABSTRACT FROM AUTHOR]