TRANSIENT-STATE RESPONSE OF WAVE PROPAGATION IN MAGNETO-ELECTRO-ELASTIC SQUARE COLUMN

This is a continued work in studying the wave propagation in a magneto-electroelastic square column （MEESC）. Based on the analytic dispersive equation, group velocity equation and steady-state response obtained in our previous paper ＇Steady-state response of the wave propagation in a magneto-electro-elastic square column＇ published in CME, the dynamical behavior of MEESC was studied in this paper. The unlimited column is an open system. The transientstate response in the open system subjected by arbitrary external fields was derived when the propagating wave pursuing method was introduced.

Numerical Investigation on Pool Boiling Mechanism of Hybrid Structures with Metal Foam and Square Column by LBM

In the present study, pool boiling heat transfer performance and bubble behaviors of hybrid structures with metal foam and square column are investigated by lattice Boltzmann method. By using the vapor-liquid phase change model of Gong-Cheng and Peng-Robinson equation of state, the effects of structural parameters, including metal foam thickness, porosity, column height and ratio of column width(W) to gap spacing(D) are investigated in details. The results show that hybrid structure performs better than pure columnar structure in pool boiling heat transfer. The hybrid structure accelerates bubble growth by fluid disturbance while metal skeletons prevent the bubble escaping. The optimum ratio of column width to gap spacing decreases with the increase of heat flux and HTC(heat transfer coefficient) can achieve an increase up to 25% when W/D change from 5/3 to 1/3. The increase of column height enhances heat transfer by expanding surface area and providing space for bubble motion. The metal foam thickness and porosity have a little influence on pool boiling heat transfer performance, but they have an important effect on bubble motion in the regime.

Square concrete columns strengthened with carbon fiber reinforced plastics sheets at low temperatures

Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics(CFRP) sheets can be used to increase the strength and improve the serviceability of damaged concrete columns at low temperatures. The failure of the specimens,in most cases,takes place within the middle half of the columns. And the failure of strengthened columns is sudden and explosive. The CFRP sheets increase both the axial load capacity and the ultimate concrete compressive strain of the columns. The ultimate loads of strengthened columns at-10,0 and 10 ℃ increase averagely by 9.09%,6.63% and 17.83%,respectively,as compared with those of the control specimens. The axial compressive strength of strengthened columns is related to the curing temperatures. The improvement of axial compressive strength decreases with reducing temperature,and when the temperature drops to a certain value,the improvement increases with falling temperature.

Benchmark experimental study on wave run-ups of fixed four-rounded-square-column array in regular waves

Wave run-up on surface-piercing columns is an important phenomenon in offshore engineering.Previous studies have mainly focused on a single column and circular column arrays.This study is concerned with the wave run-up ratio and the wave force on a fixed array of four rounded square columns.A series of regular wave tests were conducted,and the effects of wave periods and steepness were investigated.The nonlinearity of the wave run-up under incident waves with a small period is more sensitive to wave steepness.Utilizing empirical mode decomposition(EMD)and fast Fourier transform(FFT)methods,the measured signals were separated into three components representing characteristics of the incident wave component(IMF1),near-field interference(IMF2),and far-field low frequency reflected wave(IMF3),respectively.The proposed methods are helpful for studying the mechanism of near-field interference,and the experimental data are essential benchmarks for validating further numerical simulations of wave runups on rounded square columns.

A COLUMN RECURRENCE ALGORITHM FOR SOLVING LINEAR LEAST SQUARES PROBLEM

A new column recurrence algorithm based on the classical Greville method and modified Huang update is proposed for computing generalized inverse matrix and least squares solution. The numerical results have shown the high efficiency and stability of the algorithm.