地震作用下结构的AMTMD主动控制策略

提出了一种新的控制策略——主动多重调谐质量阻尼器(AMTMD)．AMTMD控制系统频率呈线性分布．AMTMD保持相同的刚度和阻尼但质量变化．AMTMD的主动控制力采用Roorda(1975)提出的生成模式．基于结构的广义振型模型，导出了设置AMTMD时结构的动力放大系数(DMF)．于是AMTMD优化准则选择为结构最大动力放大系数的最小值的最小化．分别使用位移、速度和加速度传感器，通过最优搜寻，研究了反映AMTMD有效性和鲁棒性的参数．这些参数包括：频率间隔、平均阻尼比、调谐频率比、Min．Min．Max．DMF、标准化反馈增益系数和环增益系数．为比较，同时考虑了多重调谐质量阻尼器和主动调谐质量阻尼器．而且，数值结果表明：AMTMD比MTMD具有更高的有效性和鲁棒性且ATMD也有更高的有效性．     

THERMODYNAMIC AND PARTICLE-DYNAMIC STUDIES ON SYNTHESIS OF SILICA NANOPARTICLES USING MICROWAVE-INDUCED PLASMA CVD

1. Introduction1.1 Silica nanoparticles and synthesis methods Silica (SiO2) nanoparticles are widely used in industry asan active filler for polymer reinforcement, a rheologicaladditive in fluids, a free flow agent in powders, and anagent for chemical mechanical polishing during IC (inte-grated circuit) fabrication (Sniegowski & de Boer, 2000).Silica powder is also used for producing silicon carbide(Koc & Cattamanchi, 1998) or opaque silica aerosols (Leeet al., 1995). Many methods can …     

Escape of Brownian particles and stochastic resonance with low-temperature quantum fluctuations

In this paper, we investigate the escape of Brownian particles and stochastic resonance (SR) with low-temperatures quantum fluctuations by using the quantum Smoluchowski equations at low-temperature. Two specific examples have been considered: one is the example of bistable system, and the other is the example of metastable system. The explicit expressions of the mean-first passage time (MFPT) and signal-to-noise ratio (SNR) for both specific examples are obtained, respectively. Based on the numerical compu...     

Silver(I)-mediated reaction of trimethylsilylated arylacetylenes with sulfonyl chlorides:Unexpected formation of vinvl sulfones

A novel reaction of trimethylsilylated arylacetylenes with sulfonyl chlorides was performed in the presence of silver nitrate or triflate.Conjugated vinyl sulfones as dramatic products were obtained in moderate yields and with Z-selectivity.A free radical mechanism has been proposed to account for the formation of the products.     

Editorial for Special Issue on Terahertz Technologies and Applications

Terahertz radiation,defined in the frequency range of 0.1-10 THz,has been exploited to demonstrate unique properties that do not apply to the adjacent domains of the electromagnetic waves,such as infrared and microwave.Recent advances in terahertz science and technology hold promise for a wide variety of essential applications,particularly in spectroscopy,sensing,imaging,non-destructive detections,and communications.This focus issue is comprised of invited and contributed original     

相变材料接触熔化的研究

对有关相变材料接触熔化的研究成果进行了全面的综述, 内容包括:封闭空间的接 触熔化、围绕热源的接触熔化、滑动接触熔化、滚动接触熔化、冰的压力熔化、接 触熔化的量级分析与修正、由液体边界层内的热扩散引起的熔化、不连续接触点上 熔化与润滑、固体内部传热的影响、玻璃的软化与接触熔化.     

Scintillation reduction using multi-beam propagating technique in atmospheric WOCDMA system

We propose employing multi-beam propagating technology to mitigate the influence of atmospheric scintillation to the wireless optical code division multiple access (WOCDMA) system and then deduce the bit error rate (BER) formulas of systems in weak and strong scintillations,respectively.According to simulation experiment results,multi-beam propagation can improve the system performance very well compared with single-beam propagating technique.Moreover,the more beams we use,the better the performance we get.When the received optical power is-30 dBm,the BER of the system employing four beams is 5 and 1 dB lower than that of using single-beam propagating technique in weak and strong scintillations,respectively.     

Investigation of morphology selection for CBr_4-C_2Cl_6 alloy in three dimensions with multi-phase field method

With the multi-phase field model, the unidirectional solidification with constant velocity growth and variable velocity growth of the CBr4-C2Cl6 eutectic alloy is simulated in three dimensions. The simulated results with constant velocity growth show that with the increase of pulling velocity, the morphology of the CBr4-C2Cl6 alloy evolves in the sequence of lamellar merging →lamellar-rod transition→stable lamellar growth→oscillating growth→lamellar branching. A morphology selection map is established with ...     

Electromechanical cracking in ferroelectrics driven by large scale domain switching

Experimental results indicate three regimes for cracking in a ferroelectric double cantilever beam (DCB) under combined electromechanical loading. In the loading, the maximum amplitude of the applied electric field reaches almost twice the coercive field of ferroelectrics. Thus, the model of small scale domain switching is not applicable any more, which is dictated only by the singular term of the crack tip field. In the DCB test, a large or global scale domain switching takes place instead, which is driven...     

Modelling of multi-bodies in close proximity under water waves——Fluid resonance in narrow gaps

Viscous fluid model and potential flow model with and without artificial damping force(f=-μV,μ the damping coefficient and V the local averaging flow velocity) are employed in this work to investigate the phenomenon of fluid resonance in narrow gaps between multi-bodies in close proximity under water waves.The numerical results are compared with experimental data available in the literature.The comparison demonstrates that both the viscous fluid model and the potential flow model are able to predict the res...