Massive dust of exhausted airflow easily diffuses to the industrial square while hoisting shaft is used as return shaft in the retrograde ventilation,and certainly there is a problem of dust scattering and noise excee...Massive dust of exhausted airflow easily diffuses to the industrial square while hoisting shaft is used as return shaft in the retrograde ventilation,and certainly there is a problem of dust scattering and noise exceeding standard. In order to solve the problem,the coupled technology of dedusting and noise reduction in airshaft outlet was investigated and the device with the function of Dedusting and noise Reduction(DR) was originated. The device is named as DR diffuser,which comprehensively utilizes mechanisms of inertia-gravity dedusting and absorption-insulation sound. The DR diffuser has been applied to Xingdong Coal Mine,and the testing results show that:a. the resistance of DR diffuser is lower than 60 Pa;b. the noise level reaches to 49.2 dB(A);c. the dedusting efficiency of above 50 μm is higher than 85 %;d. dynamic pressure recovered from the outlet of main fan is larger than 50 Pa. The above measured data illustrates that comprehensive benefit of the DR diffuser is good,and the device is worth of applying to engineering site.展开更多
Modal identification involves estimating the modal parameters, such as modal frequencies, damping ratios, and mode shapes, of a structural system from measured data. Under the condition that noisy impulse response sig...Modal identification involves estimating the modal parameters, such as modal frequencies, damping ratios, and mode shapes, of a structural system from measured data. Under the condition that noisy impulse response signals associated with multiple input and output locations have been measured, the primary objective of this study is to apply the local or global noise removal technique for improving the modal identification based on the polyreference time domain (PTD) method. While the traditional PTD method improves modal parameter estimation by over-specifying the computational model order to absorb noise, this paper proposes an approach using the actual system order as the computational model order and rejecting much noise prior to performing modal parameter estimation algorithms. Two noise removal approaches are investigated: a "local" approach which removes noise from one signal at a time, and a "global" approach which removes the noise of multiple measured signals simultaneously. The numerical investigation in this article is based on experimental measurements from two test setups: a cantilever beam with 3 inputs and 10 outputs, and a hanged plate with 4 inputs and 32 outputs. This paper demonstrates that the proposed noise-rejection method outperforms the traditional noise-absorption PTD method in several crucial aspects.展开更多
基金supported by the project of Hunan Province Science and Technology(No.2007FJ1012 )project of Scientific Research Fund of Hunan Provincial Education Department(No.09CY014)Doctoral Fund of HNUST
文摘Massive dust of exhausted airflow easily diffuses to the industrial square while hoisting shaft is used as return shaft in the retrograde ventilation,and certainly there is a problem of dust scattering and noise exceeding standard. In order to solve the problem,the coupled technology of dedusting and noise reduction in airshaft outlet was investigated and the device with the function of Dedusting and noise Reduction(DR) was originated. The device is named as DR diffuser,which comprehensively utilizes mechanisms of inertia-gravity dedusting and absorption-insulation sound. The DR diffuser has been applied to Xingdong Coal Mine,and the testing results show that:a. the resistance of DR diffuser is lower than 60 Pa;b. the noise level reaches to 49.2 dB(A);c. the dedusting efficiency of above 50 μm is higher than 85 %;d. dynamic pressure recovered from the outlet of main fan is larger than 50 Pa. The above measured data illustrates that comprehensive benefit of the DR diffuser is good,and the device is worth of applying to engineering site.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51079134 and 51009124)the NSFC Major International Joint Research Project (Grant No. 51010009)+2 种基金the Program for Changjiang Scholars and Innovative Research Team in University (Grant No. PCSIRT 1086)the Natural Science Foundation of Shandong Province(Grant Nos. ZR2011EEQ022 and 2009ZRA05100)the Fundamental Research Funds for the Central Universities (Grant Nos. 27R1202008A and27R1002076A)
文摘Modal identification involves estimating the modal parameters, such as modal frequencies, damping ratios, and mode shapes, of a structural system from measured data. Under the condition that noisy impulse response signals associated with multiple input and output locations have been measured, the primary objective of this study is to apply the local or global noise removal technique for improving the modal identification based on the polyreference time domain (PTD) method. While the traditional PTD method improves modal parameter estimation by over-specifying the computational model order to absorb noise, this paper proposes an approach using the actual system order as the computational model order and rejecting much noise prior to performing modal parameter estimation algorithms. Two noise removal approaches are investigated: a "local" approach which removes noise from one signal at a time, and a "global" approach which removes the noise of multiple measured signals simultaneously. The numerical investigation in this article is based on experimental measurements from two test setups: a cantilever beam with 3 inputs and 10 outputs, and a hanged plate with 4 inputs and 32 outputs. This paper demonstrates that the proposed noise-rejection method outperforms the traditional noise-absorption PTD method in several crucial aspects.
