Acceleration harmonic estimation for a hydraulic shaking table by using particle swarm optimization

The acceleration response of a servo-hydraulic shaking table to a sinusoidal input motion is inevitably distorted by parasitic harmonic content caused by inherent non-linearities within the system. Herein, an algorithm is developed to characterize these parasitic motions in order to facilitate harmonic cancellation. The proposed algorithm is based on particle swarm optimization (PSO). Optimization is achieved by each particle’s movement, updated by its local best-known position and global best-known position according to a fitness function, which itself is a function of the estimation error between the identified acceleration and the original acceleration response. The estimation scheme is validated by experiments on a servo-hydraulic shaking table and results are compared with a more traditional harmonic analysis. </jats:p

Effect of solvent extraction on the composition of coal tar residues and their pyrolysis characteristics

A large amount of coal tar residues (CTRs) produced in the coal coking or gasification industry has not been effectively utilized in China. In this study, CTRs are extracted by 12 organic solvents. Detailed investigations are carried out via ultimate analysis, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG) analyzer. The pyrolysis process of CTRs and their extraction residues (RCTRs) can be accurately fitted by Coast-Redfern integral model. The results indicate that the reaction order (n), apparent activation energy (Ea) and pre-exponential factor (A) were in the range of 2–7, 34.42–60.08 kJ mol−1 and 102-105 min−1, respectively. Correlations are observed between parameters (H, C, O, H/C, WT, Rmax, n, Ea, and lnA) and the yield of RCTRs, suggesting that the composition and pyrolysis behavior are controlled by the solvent extraction. Specifically, extraction with n-heptane, methanol and ethanol could reduce the Ea and promote CTRs decomposition by disrupting the noncovalent bonds. When extracted with CS2, DMF, benzene, toluene, acetone, etc. the recovery rate of tar and the yield of pyrolysis products are improved, however, the reactivity decrease due to the increase in activation energy.</p