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Search Results: 1 - 10 of 12694 matches for " Luo Chunrong "
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Double-negative acoustic metamaterial based on hollow steel tube meta-atom
Huaijun Chen,Hongcheng Zeng,Changlin Ding,Chunrong Luo,Xiaopeng Zhao
Physics , 2012, DOI: 10.1063/1.4790312
Abstract: We presented an acoustic 'meta-atom' model of hollow steel tube (HST). The simulated and experimental results demonstrated that the resonant frequency is closely related to the length of the HST. Based on the HST model, we fabricated a two-dimensional (2D) acoustic metamaterial (AM) with negative effective mass density, which put up the transmission dip and accompanied inverse phase in experiment. By coupling the HST with split hollow sphere (SHS), another kind of 'meta-atom' with negative effective modulus in the layered sponge matrix, a three-dimensional (3D) AM was fabricated with simultaneously negative modulus and negative mass density. From the experiment, it is shown that the transmission peak similar to the electromagnetic metamaterials exhibited in the double-negative region of the AM. We also demonstrated that this kind of doble-negative AM can faithfully distinguish the acoustic sub-wavelength details ({\lambda}/7) at the resonance frequency of 1630Hz.
Experimental Observation of Reversed Doppler Effects in Acoustic Metamaterials
Shilong Zhai,Xiaopeng Zhao,Song Liu,Chunrong Luo
Physics , 2015,
Abstract: This paper reports an experimental observation of broadband reversed Doppler effects using an acoustic metamaterial with seven flute-like double-meta-molecule clusters. Simulations and experiments verify that this locally resonant acoustic metamaterial with simultaneous negative elastic modulus and mass density can realize negative refraction in a broad frequency range. The constructed metamaterial exhibits broadband reversed Doppler effects. The frequency shift increases continuously as the frequency increases. The assembling of double-meta-molecule clusters introduces a new direction in designing double-negative acoustic metamaterials in an arbitrarily broad frequency range and other various applications.
Broadband dispersionless polarization rotation with composite chiral metamaterials
Kun Song,Changlin Ding,Yahong Liu,Chunrong Luo,Xiaopeng Zhao
Physics , 2015,
Abstract: We propose a planar composite chiral metamaterial (CCMM) by symmetrically inserting a metallic mesh between two layers of conjugated gammadion resonators. As the elaborate CCMM operates in the frequency region of off-resonance, it therefore presents loss-less and dispersion-free features. It can achieve flat polarization rotation simultaneously accompanied with high transmission and extremely low ellipticity in a broad bandwidth. In the meanwhile, this intriguing CCMM shows more superiorities in polarization rotation power and operating bandwidth than the pure chiral metamaterial just composed of conjugated gammadions. Due to the fascinating properties, the proposed CCMM is greatly appealing for controlling the polarization state of the electromagnetic waves.
Panel-allocated defect SRRs effect in X-band LHMs
Lei Kang,Chunrong Luo,Qian Zhao,Juan Song,Quanhong Fu,Xiaopeng Zhao
Chinese Science Bulletin , 2004, DOI: 10.1007/BF03183708
Abstract: We experimentally investigated the defect effects of LHMs when panel-allocated defects SRRs are introduced. By measuring the X-band transmission through metamaterial with different sizes and orientations panelallocated defect SRRs, it was found that characters of resonant peak, including resonance frequency, magnitude and band pass, markedly change. And the panel-allocated defects in LHMs have more effect on electromagnetic behavior than that of dot and linear ones. It is thought that the existences of panel-allocated defects break the symmetry of perfect LHMs and result in a new electromagnetic resonance.

Luo Chunrong,Zhang Zhaodong,Zhao Xiaopeng,

光子学报 , 1997,
Abstract: In this paper,the diffraction character of ER fluids has been studied. It is found that ERfluid can be considered as an optical grating when an external electric field is applied. With the electricfield to be rising, the grating constants increase, that is, the grating is adjustable. Meanwhile,EMR fluids are studied in different condition. When an electric -field and a magnetic field are applied atthe same time, each other perpendicularly,a two-dimension mesh structure is found in EMR fluids,and the laser diffraction fringe photograph has been obtained.
A Visible Metamaterial with Low Loss Made by Bottom-Up Self-Assembly
Boyi Gong,Xiaopeng Zhao,Zhenzhen Pan,Sa Li,Xiaonong Wang,Yan Zhao,Chunrong Luo
Physics , 2013,
Abstract: Since the introduction of the artificially designed negative-index metamaterial (NIM) introduced in 2001, its extraordinary electromagnetic properties, which cannot be attained from naturally occurring materials, have continuously attracted many researchers to study them. Various types of NIMs with the resonant frequencies shifted from gigahertz all the way to higher frequencies have been actualized over the past decade. For the actual applications, the most fascinating and significant goal of research on NIMs is to achieve negative refraction at visible wavelengths. According to the effective medium theory, the interior structural unit of NIMs must be on a scale much smaller than the operating wavelength.
Gas Chromatographic Determination of Residual Toluene in Plastic Packing Bags

Ye Fen,Luo Chunrong,Xu Guowang,Zhang Yukui,

色谱 , 1997,
Abstract: A method for analysis of residual toluene in plastic packing bags by gas chromatographic headspace analysis is presented. This method is very simple and accurate. It only requires one column: 0.5 m x 2 mm i.d. packed with 102 white support DMCS coated with 20% PEG-20M. The relation between the preheating temperature of sample and the peak height of toluene can be approximately expressed as H=4.156e(0.126T). The precision of this method is 4% and its detectable limit is 0.031 mg (toluene)/m2.
An Improved Method for the Analysis of Residual Solvent in Evening Primrose Oil(EPO)

Ye Fen,Luo Chunrong,Zhang Xiangmin,Zhang Yukui,

色谱 , 1994,
Abstract: n improved method for the analysis of residual solvent in EPO by gas chromatographic headspaceanalysis is presented.A better accuracy and a lower detectable limit of this method in comparing with thoseof GB 5009.37-85 were obtained.
Chromatographic Analysis of Trace Impurities in Acrylamide

Xiu Zhenjia,Zhang Tongfeng,Luo Chunrong,Xu Guowang,Zhang Yukui,

色谱 , 1995,
Abstract: 丙烯酰胺中痕量杂质色谱分析修振佳,张桐凤,罗春荣,许国旺,张玉奎(中国科学院大连化学物理研究所,国家色谱研究分析中心大连116012)1前言合成聚丙烯酰胺的单体丙烯酰胺的纯度可能影响其聚合速度和产物的分子量,为保证聚丙烯酰胺产品质量,分析单体丙烯酰胺...
A Critical Review of Naphthalene Sources and Exposures Relevant to Indoor and Outdoor Air
Chunrong Jia,Stuart Batterman
International Journal of Environmental Research and Public Health , 2010, DOI: 10.3390/ijerph7072903
Abstract: Both the recent classification of naphthalene as a possible human carcinogen and its ubiquitous presence motivate this critical review of naphthalene’s sources and exposures. We evaluate the environmental literature on naphthalene published since 1990, drawing on nearly 150 studies that report emissions and concentrations in indoor, outdoor and personal air. While naphthalene is both a volatile organic compound and a polycyclic aromatic hydrocarbon, concentrations and exposures are poorly characterized relative to many other pollutants. Most airborne emissions result from combustion, and key sources include industry, open burning, tailpipe emissions, and cigarettes. The second largest source is off-gassing, specifically from naphthalene’s use as a deodorizer, repellent and fumigant. In the U.S., naphthalene’s use as a moth repellant has been reduced in favor of para-dichlorobenzene, but extensive use continues in mothballs, which appears responsible for some of the highest indoor exposures, along with off-label uses. Among the studies judged to be representative, average concentrations ranged from 0.18 to 1.7 μg m -3 in non-smoker’s homes, and from 0.02 to 0.31 μg m -3 outdoors in urban areas. Personal exposures have been reported in only three European studies. Indoor sources are the major contributor to (non-occupational) exposure. While its central tendencies fall well below guideline levels relevant to acute health impacts, several studies have reported maximum concentrations exceeding 100 μg m -3, far above guideline levels. Using current but draft estimates of cancer risks, naphthalene is a major environmental risk driver, with typical individual risk levels in the 10 -4 range, which is high and notable given that millions of individuals are exposed. Several factors influence indoor and outdoor concentrations, but the literature is inconsistent on their effects. Further investigation is needed to better characterize naphthalene’s sources and exposures, especially for indoor and personal measurements.
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