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Analytical solution for SH wave propagating through a graded plate of metamaterial

Jinfeng ZHAO, Yongdong PAN, Zheng ZHONG

《机械工程前沿（英文）》 2011年第6卷第3期页码 301-307 doi: 10.1007/s11465-011-0238-7

摘要：

A physical model for the shear horizontal (SH) wave propagating from left-handed material (LHM) through a graded or transition layer to right-handed material (RHM) has been proposed in this paper. After the comparison of the basic wave equations of the electromagnetic, longitudinal, and SH waves, it is found that they take similar differential form. The analytical solutions have been found for power law, hyperbolic, and polynomial profiles. Numerical waveforms of the amplitude and phase of the displacement are obtained for the corresponding profiles. It is found that the waveforms are symmetric for the power law and hyperbolic profiles, and that the waveform for the polynomial profile is shifted and non-symmetric. The shift along with the anti-symmetric profile may provide a way to monitor the wave behavior of the metamaterials.

关键词： left-handed material (LHM) metamaterial shear horizontal (SH) wave

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Experimental study on premixed combustion of spherically propagating methanol-air-nitrogen flames

Xiangang WANG, Zhiyuan ZHANG, Zuohua HUANG, Xibin WANG, Haiyan MIAO,

《能源前沿（英文）》 2010年第4卷第2期页码 223-233 doi: 10.1007/s11708-010-0016-y

摘要： The outward propagation and development of surface instability of the spark-ignited spherical premixed flames for methanol-air-nitrogen mixtures were experimentally studied by using a constant volume combustion chamber and a high-speed schlieren photography system. The laminar burning velocities, the mass burning fluxes, and the Markstein lengths were obtained at different equivalence ratios, dilution ratios, initial temperatures, and pressures. The laminar burning velocities and the mass burning fluxes give a similar curve versus the equivalence ratios. They increase with the increase of initial temperature and decrease with the increase of dilution ratio. The laminar burning velocity decreases with elevating the initial pressure, while the mass burning flux increases with the increase of the initial pressure. Markstein length decreases slightly with the increase of initial temperature for the rich mixtures. High initial pressure corresponds to low Markstein length. Markstein length increases with the increase of dilution ratio, which is more obvious when the mixture becomes leaner. Equivalence ratio has a slight impact on the development of the diffusive-thermal cellular structure at elevated initial pressures. The initial pressure has a significant influence on the occurrence of the flame front cellular structure. At the elevated pressures, the cracks on the flame surface branch and develop into the cell structure. These cells are bounded by cracks emitting a bright light, which may indicate soot formation. For very lean mixture combustion, the buoyancy effect and cooling effect from the spark electrodes have a significant impact on the flame propagation. The hydrodynamic instability, inhibited with the increase of initial temperature around the stoichiometric equivalence ratio, is enhanced with the increase of initial pressure and suppressed by mixture dilution.

关键词： methanol spherical flame propagation characteristics flame instabilities

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Structure and performance of welding joint of Q235 steel welded by SHS welding

Junzhi HU, Sumei WANG, Xiaoli ZHAO, Shilin ZHU, Botao YU,

《机械工程前沿（英文）》 2010年第5卷第2期页码 189-193 doi: 10.1007/s11465-010-0003-3

摘要： A self-propagating high-temperature synthesis (SHS) welding-pen that can weld steel workpiece from 6 to 10 mm is developed and welds the Q235 steel. The structure and properties of the welding joint are studied. The result indicates that this type of welding is melting and the fusion zone is clear. The tensile-strength of the welding joint is 283 MPa, flexural strength is 628 MPa, impact toughness is 46.43 J·cm, and the microhardness of the welding joint and fusion zone are 230 HV and 255.6€HV, respectively. The mircohardness of the fusion zone and the welding line are higher than that of the matrix.

关键词： self-propagating high-temperature synthesis (SHS) welding welding line structure and performance melting

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Air-borne noise of thermal module and system for notebook personal computers: experimental study

SHI Junye, JIANG Cailing, QIAO Junsheng, CHEN Jiangpin, LI Xiaoping, ZHANG Xiaojun

《能源前沿（英文）》 2008年第2卷第2期页码 174-178 doi: 10.1007/s11708-008-0034-1

摘要： Thermal performance is the most important issue to be considered when a thermal module is designed for a notebook personal computer (PC). Because the fan causes air-borne noise and affects the user’s comfort, the acoustic characteristics of the module attract more attention. Experiments were conducted to study the noise sources, the noise characteristic and the main factors influencing the noise level. The difference between the air-borne noise of the thermal module and the whole computer system was analyzed and its propagating characteristics were derived. The influence of I/O ports on the air-borne noise was also studied experimentally.

关键词： air-borne attention propagating characteristic personal computer