A Method for Mill Monitoring Based on Inter-insert Periodic Correlation Using Singular Value Decomposition (SVD)

This paper introduces a method to monitor the wear of end milling tools in real-time production based on inter-insert periodic correlation. The aim is to detect abnormal behavior of the cutter as early as possible to prevent severe tool failure and subsequent losses. The approach takes advantage of the angular domain to segment the signal in periodic cycles of the same angular duration, which are then amenable to correlation analysis. An ordered separability index with latent correlation characteristics is proposed to assess the current operating state of the tool. A series of simulations with existing experimental data are run to test the feasibility of the proposed index and to calculate the corresponding confidence interval. This approach has a high potential to form an efficient tool condition monitoring system. Compared to the traditional teach-in method, this method is more independent of the cutting conditions (changes of velocity or direction) and has no requirement for a trial cut, making the method useful for small batch production and can reduce the rate of false alarms.

Z-complementary pairs with flexible lengths and large zero odd-periodic correlation zones

<p style='text-indent:20px;'>Z-complementary pairs (ZCPs) have been widely used in different communication systems. In this paper, we first investigate the odd-periodic correlation property of ZCPs, and propose a new class of ZCPs, called ZOC-ZCPs with zero correlation zone (ZCZ) width <inline-formula><tex-math id="M1">\begin{document}$ Z $\end{document}</tex-math></inline-formula> and zero odd-period correlation zone (ZOCZ) width <inline-formula><tex-math id="M2">\begin{document}$ Z_{odd} = Z $\end{document}</tex-math></inline-formula> by horizontal concatenation of a certain combination of some known ZCPs. Particularly, based on any known Golay pair, we can generate a class of GCPs of more flexible length whose ZOCZ width is larger than a quarter of the sequence length.</p>

Correlation Property and Low Bound of Time-Hopping Codes for UWB Communications

In this paper, we analyze correlation property of time-hopping (TH) codes for time-hopping spread spectrum ultra wideband (THSS-UWB) communication systems. Several different definitions of TH periodic correlation function are compared and discussed. Based on the comparison, the relation between TH codes and frequency-hopping (FH) codes is obtained. Also, the averages of TH periodic correlation function values are investigated, and the relations between averages and four parameters of TH codes are introduced. Based on the result, low bound of maximal TH correlation function values is further given, where the expression of low bound of TH codes relates codes period, the number of time slots, TH codes family size and maximal TH correlation function values.