Testing the parts of mechanical products and ensuring their accuracy to the design requirements are essential to products’ quality, market competitiveness and manufacturers’ maximum economical benefits from these pr...Testing the parts of mechanical products and ensuring their accuracy to the design requirements are essential to products’ quality, market competitiveness and manufacturers’ maximum economical benefits from these products. One of the latest subjects of study in the area of precision measurement is the testing of parts to follow the relative requirements, viz. design requirements for the size tolerance of size features and related geometrical tolerances of the central feature, including the envelope requirement, maximum material requirement and least material requirement. The article analyzes test methods for parts to follow the envelope requirement or maximum material requirement, as well as further requirements of geometrical tolerances for its central feature. The method is effective in improving product quality and rejecting unqualified parts.展开更多
A reduced state Soft Input Soft Output (SISO) a posteriori probability algorithm for Seri-ally Concatenated Continuous Phase Modulation (SCCPM) is proposed in this paper. Based on the Reduced State Sequence Detection ...A reduced state Soft Input Soft Output (SISO) a posteriori probability algorithm for Seri-ally Concatenated Continuous Phase Modulation (SCCPM) is proposed in this paper. Based on the Reduced State Sequence Detection (RSSD),it has more general form compared with other reduced state SISO algorithms. The proposed algorithm can greatly reduce the state number,thus leads to the computation complexity reduction. It also minimizes the degradation in Euclidean distance with decision feedback in the reduced state trellis. Analysis and simulation results show that the perform-ance degradation is little with proper reduction scheme.展开更多
According to the time&space conversion relations and different frequency phase detection principle,an ultra-high precision time&frequency measurement method is proposed in this paper.The higher accuracy and st...According to the time&space conversion relations and different frequency phase detection principle,an ultra-high precision time&frequency measurement method is proposed in this paper.The higher accuracy and stability of the speed of light and electromagnetic signals during the transmission in space or a specific medium enable the measurement of short time interval which uses the coincidence detection of signal’s transmission delay in length.The measurement precision better than 10 picoseconds can be easily obtained.The method develops the length vernier utilizing the stability of signal’s transmission delay,minimizes the fuzzy region of phase coincidence between the standard frequency signal and the measured signal,approaches the best phase coincidences and therefore improves the measurement precision which is higher than the precision provided by the traditional methods based on frequency processing.Besides,the method costs less than the traditional methods and can also solve the problem of the measurement of super-high frequency.Experimental results show the method can improve the measurement precision to 10 12/s in the time&frequency domain.展开更多
文摘Testing the parts of mechanical products and ensuring their accuracy to the design requirements are essential to products’ quality, market competitiveness and manufacturers’ maximum economical benefits from these products. One of the latest subjects of study in the area of precision measurement is the testing of parts to follow the relative requirements, viz. design requirements for the size tolerance of size features and related geometrical tolerances of the central feature, including the envelope requirement, maximum material requirement and least material requirement. The article analyzes test methods for parts to follow the envelope requirement or maximum material requirement, as well as further requirements of geometrical tolerances for its central feature. The method is effective in improving product quality and rejecting unqualified parts.
基金Supported by NSFC & Microsoft Asia (60372048)China TRAPOYT, NSFC key project (60496316)+2 种基金863 Project (2005AA123910)RFDP (20050701007)MOE Key Project (104171).
文摘A reduced state Soft Input Soft Output (SISO) a posteriori probability algorithm for Seri-ally Concatenated Continuous Phase Modulation (SCCPM) is proposed in this paper. Based on the Reduced State Sequence Detection (RSSD),it has more general form compared with other reduced state SISO algorithms. The proposed algorithm can greatly reduce the state number,thus leads to the computation complexity reduction. It also minimizes the degradation in Euclidean distance with decision feedback in the reduced state trellis. Analysis and simulation results show that the perform-ance degradation is little with proper reduction scheme.
基金supported by the National Natural Science Foundation of China (Grant No. U1304618)the Open Fund of Key Laboratory of Precision Navigation and Timing Technology of Chinese Academy of Sciences(Grant No. 2012PNTT01)+5 种基金the Postdoctoral Grant of China (Grant Nos. 2011M501446, 2012T50798)the Basic and Advanced Technology Research Foundation of Henan Province under Grant (Grant No. 122300410169)The Key Science and Technology Foundation of Henan Province under Grant (Grant No. 132102210180)the Doctor Fund of Zhengzhou University of Light Industry under (Grant No. 2011BSJJ031)the Scientific Research Fund of Zhengzhou University of Light Industry under (Grant No. 2012XJJ009)the Fundamental Research Funds for the Central Universities(Grant No. K5051204003)
文摘According to the time&space conversion relations and different frequency phase detection principle,an ultra-high precision time&frequency measurement method is proposed in this paper.The higher accuracy and stability of the speed of light and electromagnetic signals during the transmission in space or a specific medium enable the measurement of short time interval which uses the coincidence detection of signal’s transmission delay in length.The measurement precision better than 10 picoseconds can be easily obtained.The method develops the length vernier utilizing the stability of signal’s transmission delay,minimizes the fuzzy region of phase coincidence between the standard frequency signal and the measured signal,approaches the best phase coincidences and therefore improves the measurement precision which is higher than the precision provided by the traditional methods based on frequency processing.Besides,the method costs less than the traditional methods and can also solve the problem of the measurement of super-high frequency.Experimental results show the method can improve the measurement precision to 10 12/s in the time&frequency domain.
