针对工况传递路径分析(Operational transfer Path Analysis OPA)方法在工程应用中虽具吸引力、尚存准确性难以满足船舶实际应用需求等问题,将多源信号视为卷积混叠,提出耦合振动噪声源分离方法。建立船舶OPA模型,结合船舶传递路径振声...针对工况传递路径分析(Operational transfer Path Analysis OPA)方法在工程应用中虽具吸引力、尚存准确性难以满足船舶实际应用需求等问题,将多源信号视为卷积混叠,提出耦合振动噪声源分离方法。建立船舶OPA模型,结合船舶传递路径振声测试试验对模型可行性、正确性进行验证。讨论观测点数目及不同工况组合对新OPA模型影响,给出有效选取原则。结果表明,新OPA模型可准确、高效进行船舶噪声源识别、声场预报及状态监测,工程应用前景广阔。展开更多
Engine noise source identification is essential for making noise reduction strategies.Predominant noise sources of engines are normally identified as some cover components such as oil pan, valve cover and front gear c...Engine noise source identification is essential for making noise reduction strategies.Predominant noise sources of engines are normally identified as some cover components such as oil pan, valve cover and front gear cover etc. The radiated noise sources of a 6-cylinder construction diesel engine are identified with two methods-lead covering technique and surface vibration technique,and the ranking of the major cover on the basis of acoustic power is presented in this paper. Firstly the sound power level of these cover components and their contributions to the total acoustic power are determined with lead covering method under hemi-anechoic condition. Then the vibration characteristics of these components are investigated. The sound power level of various components is predicted via the mean square area average vibration. Both results basically agree well and verify the effectiveness of both techniques in engineering field.展开更多
A new configuration for delay cells used in voltage controlled oscillators is presented. A jitter comparison between the source-coupled differential delay cell and the proposed CMOS inverter based delay cell is given....A new configuration for delay cells used in voltage controlled oscillators is presented. A jitter comparison between the source-coupled differential delay cell and the proposed CMOS inverter based delay cell is given. A new method to optimize loop parameters based on low-jitter in PLL is also introduced. A low-jitter 1.25GHz Serdes is implemented in a 0.35μm standard 2P3M CMOS process. The result shows that the RJ （random jitter） RMS of 1.25GHz data rate series output is 2. 3ps （0. 0015UI） and RJ （1 sigma） is 0. 0035UI. A phase noise measurement shows - 120dBc/Hz@100kHz at 1111100000 clock-pattern data out.展开更多
文摘针对工况传递路径分析(Operational transfer Path Analysis OPA)方法在工程应用中虽具吸引力、尚存准确性难以满足船舶实际应用需求等问题,将多源信号视为卷积混叠,提出耦合振动噪声源分离方法。建立船舶OPA模型,结合船舶传递路径振声测试试验对模型可行性、正确性进行验证。讨论观测点数目及不同工况组合对新OPA模型影响,给出有效选取原则。结果表明,新OPA模型可准确、高效进行船舶噪声源识别、声场预报及状态监测,工程应用前景广阔。
文摘Engine noise source identification is essential for making noise reduction strategies.Predominant noise sources of engines are normally identified as some cover components such as oil pan, valve cover and front gear cover etc. The radiated noise sources of a 6-cylinder construction diesel engine are identified with two methods-lead covering technique and surface vibration technique,and the ranking of the major cover on the basis of acoustic power is presented in this paper. Firstly the sound power level of these cover components and their contributions to the total acoustic power are determined with lead covering method under hemi-anechoic condition. Then the vibration characteristics of these components are investigated. The sound power level of various components is predicted via the mean square area average vibration. Both results basically agree well and verify the effectiveness of both techniques in engineering field.
文摘A new configuration for delay cells used in voltage controlled oscillators is presented. A jitter comparison between the source-coupled differential delay cell and the proposed CMOS inverter based delay cell is given. A new method to optimize loop parameters based on low-jitter in PLL is also introduced. A low-jitter 1.25GHz Serdes is implemented in a 0.35μm standard 2P3M CMOS process. The result shows that the RJ （random jitter） RMS of 1.25GHz data rate series output is 2. 3ps （0. 0015UI） and RJ （1 sigma） is 0. 0035UI. A phase noise measurement shows - 120dBc/Hz@100kHz at 1111100000 clock-pattern data out.
