PurposeEmbedding dimension determination in phase space reconstruction is difficult. The purpose of this paper is to present a new approach for embedding dimension determination based on empirical mode, showing that embedding dimensions for phase space reconstruction could be easily determined according to the number of intrinsic mode functions decomposed by empirical mode decomposition.Design/methodology/approachThrough the relation analysis of intrinsic mode functions and embedding dimensions, the approach for embedding dimension determination by the number of intrinsic mode functions is presented. First, a time series is decomposed into several intrinsic mode functions. Second, correlation analysis between intrinsic mode functions and original signals is investigated, and then false intrinsic mode functions could be eliminated by the analysis of correlation coefficient thresholds, which makes the embedding dimension precise. Finally, the method presented is applied to the Lorenz system, Chen's system, and the Duffing equation. Simulation results prove this method is feasible.FindingsA new approach for embedding dimension determination based on empirical mode decomposition is presented. Compared with G‐P algorithms, this new method is effective and decreases computational complexity.Research limitations/implicationsThis method provides an effective qualitative criterion to the selection of embedding dimensions in phase space reconstruction.Practical implicationsThis method could be used to determine embedding dimensions of phase space reconstruction and degree‐of‐freedom of nonlinear dynamical systems.Originality/valueThe paper proposes a new method of embedding dimension determination in phase space reconstruction.

Treatment of 1800 mg/L phenols-containing coking wastewater by the ferric carbon micro electrolysis-Fenton reagent can satisfy the demand of the biochemical waste water disposing unit.Influences of the original pH,amount of H2O2,reaction time etc.on removal effect of the residual volatile phenols in the wastewater were studied.The optimal conditions were determined by orthogonal experiments as follows: the amount of H2O2 is 3.6 mL/L,the original pH is 3.0,the best reaction time is 180 min,respectively.After the wastewater is treated by flocculation under this conditions,the phenols degrading rate is 82%.

This paper presents an improved EMD algorithm for the fault diagnosis of reciprocating pump valves with spring failure. The vibration signal of reciprocating pumps is of typical nonstationarity. Although the EMD algorithm adopting the cubic spline interpolation is an effective tool processing non-stationary signal, it couldnpsilat accurately extract fault characteristics from the highly nonstationary signals. So the paper presents a new improved EMD algorithm which adopts Piecewise Cubic Hermite Interpolating Polynomial (PCHIP) as envelope of extrema. Through the simulation and application, it can be shown that the PCHIP can extract fault characteristic of valves more exactly than the spline.