A New Multi-sensor Data Fusion Algorithm Based on EMD-MMSE

A new multi-sensor data fusion algorithm based on EMD-MMSE was proposed.Empirical mode decomposition(EMD)is used to extract the noise of every time series for estimating the variance of the noise.Then minimum mean square error(MMSE)estimator is used to calculate the weights of the corresponding series.Finally,the fused signal is the weighted addition of all these series.The experiments in lab testified the efficiency of this method.In addition,the comparison in fusion time and fusion results with existing fusion method based on wavelet and average technique shows the advantage of this method greatly.     

基于时频分析的客车加速通过噪声声源识别

应用小波包分析理论发展了基于时频分析的客车加速通过噪声声源识别技术。根据选择运行及部分覆盖方法,分别去除各声源影响,同时测得客车通过测试区域的车外加速噪声。对于噪声信号进行多层小波包分解并重构,计算每个小波包的能量及该层小波包的总能量,通过不同信号的小波包能量比较达到声源识别的目的。研究表明,该方法不仅可以清晰地分辨各噪声源能量在时-频域的分布情况,而且通过能量计算可以识别主要噪声源,为采取相适应的降噪措施提供了理论基础。     

Experimental study on dynamic response of a floating offshore wind turbine under various freak wave profiles

This study performed experimental investigation on the dynamic response of an in-place floating offshore wind turbine (FOWT) under freak wave actions. Based on the method of wave profile modulation, various freak wave profiles embedded in unidirectional Gaussian seas were generated in wave basin and the action of these waves on the FOWT was measured and analyzed, which has not been done before. The motions of FOWT were analyzed in time domain as well as time-frequency domain. The effect of freak wave parameters on FOWT motions was addressed, i.e., freak wave height, freak wave period, large crest, and deep trough. The dynamic response of FOWT was observed as a spike at the occurrence of freak wave in a conventional random wave, where the impact of freak wave can last for 17 spectral peak periods of wave. Data analysis shows that the motions of FOWT increased linearly with the freak wave height. In addition, the occurrence of freak wave induced the coupled effect on surge and pith, which was strengthen with the increase of freak wave height and wave period. Compared to a large crest, a deep trough of freak wave led to stronger motions and was supposed to be a key concern on the safety of the FOWT. The novel findings in this study provided a reference for the design of survival load on a FOWT and benchmarks for validating numerical models.     

基于SVD的地铁盾构洞门钢环空间形态参数计算

为解决现有地铁盾构隧道洞门钢环空间形态参数计算方法步骤繁琐、需要初始值等问题，在分析空间平面方程和球面方程求解系数特点的基础上，提出利用奇异值分解（SVD）法一次性解算出球面方程参数和洞门钢环所在空间平面单位法向量，再利用上述参数直接计算洞门钢环的中心位置、半径、平整度、圆度等空间形态参数。该过程无需初始值和迭代计算，更为便捷高效。为消除观测点中可能存在的粗差，进一步结合方差比值检验法实现粗差的探测。应用结果表明： SVD法计算结果与商业软件一致，即使存在粗差，利用方差比值检验法也可以准确定位粗差，二者结合具有较好的实用价值。