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Acoustic fault signal extraction via the line-defect phononic crystals

《机械工程前沿（英文）》 2022年 第17卷 第1期   页码 10-10 doi: 10.1007/s11465-021-0666-y

摘要： Rotating machine fault signal extraction becomes increasingly important in practical engineering applications. However, fault signals with low signal-to-noise ratios (SNRs) are difficult to extract, especially at the early stage of fault diagnosis. In this paper, 2D line-defect phononic crystals (PCs) consisting of periodic acrylic tubes with slit are proposed for weak signal detection. The defect band, namely, the formed resonance band of line-defect PCs enables the incident acoustic wave at the resonance frequency to be trapped and enhanced at the resonance cavity. The noise can be filtered by the band gap. As a result, fault signals with high SNRs can be obtained for fault feature extraction. The effectiveness of weak harmonic and periodic impulse signal detection via line-defect PCs are investigated in numerical and experimental studies. All the numerical and experimental results indicate that line-defect PCs can be well used for extracting weak harmonic and periodic impulse signals. This work will provide potential for extracting weak signals in many practical engineering applications.

关键词： phononic crystals     line-defect     fault signal extraction     acoustic enhancement    

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中国功能晶体研究进展 Review

王继扬,于浩海,吴以成,Robert Boughton

《工程（英文）》 2015年 第1卷 第2期   页码 192-210 doi: 10.15302/J-ENG-2015053

摘要：

功能晶体是现代科学技术发展的基础材料之一，在当前信息时代发挥着重要和关键的作用。本文总结了若干功能晶体的研究进展，综述了中国功能晶体的现状及重大成就和重要应用，讨论了功能晶体面临的挑战和机遇，提出了可能的发展方向。

关键词： 功能材料，激光晶体，非线性光学晶体，闪烁晶体， 弛豫型铁电晶体，半导体    

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Existence of complete band gaps in 2D steel-water phononic crystal with square lattice

Cunfu HE, Huanyu ZHAO, Ruiju WEI, Bin WU

《机械工程前沿（英文）》 2010年 第5卷 第4期   页码 450-454 doi: 10.1007/s11465-010-0105-y

摘要： This paper theoretically and experimentally studies the existence of complete band gaps in two-dimensional (2D) phononic crystal consisting of parallel steel rods in water with square lattice. The band structure of phononic crystal is calculated by a plane wave expansion (PWE) method. Based on the well-known ultrasonic immersion transmission technique, the overlapping transmission spectra of acoustic waves, a complete band gap, is experimentally measured along the two high-symmetry directions of the first irreducible Brillouin zone. There is a very good agreement between the experimental result and the range of frequencies of the complete band gap.

关键词： phononic crystal     plane wave expansion (PWE) method     experimental study    

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Synthesis of crystals and particles by crystallization and polymerization in droplet-based microfluidic

Jingtao WANG, Jin ZHANG, Junjie HAN,

《化学科学与工程前沿（英文）》 2010年 第4卷 第1期   页码 26-36 doi: 10.1007/s11705-009-0292-4

摘要： The recent advances in crystallization and polymerization assisted by droplet-based microfluidics to synthesize micro-particles and micro-crystals are reviewed in this paper. Droplet-based microfluidic devices are powerful tools to execute some precise controls and operations on the flow inside microchannels by adjusting fluid dynamics parameters to produce monodisperse emulsions or multiple-emulsions of various materials. Major features of this technique are producing particles of monodispersity to control the shape of particles in a new level, and to generate droplets of diverse materials including aqueous solutions, gels and polymers. Numerous microfluidic devices have been employed to generate monodisperse droplets of range from nm to μm, such as T junctions, flow-focusing devices and co-flow or cross-flow capillaries. These discrete, independently controllable droplets are ideal microreactors to be manipulated in the channels to synthesize the nanocrystals, protein crystals, polymer particles and microcapsules. The generated monodisperse particles or crystals are to meet different technical demands in many fields, such as crystal engineering, encapsulation and drug delivery systems. Microfluidic devices are promising tools in the synthesis of micron polymer particles that have diverse applications such as the photonic materials, ion-exchange and chromatography columns, and field-responsive rheological fluids. Processes assisted by microfluidic devices are able to produce the polymer particles (including Janus particles) with precise control over their sizes, size distribution, morphology and compositions. The technology of microfluidics has also been employed to generate core-shell microcapsules and solid microgels with precise controlled sizes and inner structures. The chosen “smart” materials are sensitive to an external stimulus such as the change of the pH, electric field and temperature. These complex particles are also able to be functionalized by encapsulating nanoparticles of special functions and by attaching some special groups like targeting ligands. The nucleation kinetics of some crystals like KNO was investigated in different microfluidic devices. Because of the elimination of the interactions among crystallites in bulk systems, using independent droplets may help to measure the nucleation rate more accurately. In structural biology, the droplets produced in microfluidic devices provide ideal platforms for protein crystallization on the nanoliter scale. Therefore, they become one of the promising tools to screen the optimal conditions of protein crystallization.

关键词： core-shell     monodisperse     nucleation     Microfluidic     different technical    

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Filtration ability of hollow fiber membrane for production of magnesium ammonium phosphate crystals by

H. Watamura, H. Marukawa, I. Hirasawa

《化学科学与工程前沿（英文）》 2013年 第7卷 第1期   页码 55-59 doi: 10.1007/s11705-013-1312-y

摘要： Relationship between magnesium ammonium phosphate (MAP) crystal properties and the filtration ability of hollow fiber membrane (HFM) were investigated. Phosphorus recovery process by crystallization has a problem that it produces a large amount of fine crystals. So improvement of the crystallization process by combining with filtration was discussed. MAP crystals were obtained by batch reaction crystallization and the filtration characteristics were investigated. The filtration was evaluated by the specific filtration resistance ( ) on HFM. Filtered slurry was prepared with each suspension density and crystal size distribution. The solution was filtered at constant pressure of 0.02 MPa and the filtration time on each filtrated volume was recorded. As a result, decreases exponentially with suspension density increasing from 0.25 g/L to 0.5 g/L and decreases moderately with suspension density increasing from 0.5 g/L to 1.5 g/L. of large crystals decreases exponentially at less suspension density than of small crystals does. Also, increases as the ratio of the fractured crystals increases.

关键词： membrane separation     crystallization     MAP    

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Control of the agglomeration of crystals in the reactive crystallization of 5-(difluoromethoxy)-2-mercapto

Yongli WANG, Shuyuan MA, Xiaodong Lü, Chuang XIE

《化学科学与工程前沿（英文）》 2012年 第6卷 第4期   页码 423-431 doi: 10.1007/s11705-012-1211-7

摘要： 5-(Difluoromethoxy)-2-mercapto-1 -benzimidazole (DMB) was precipitated by adding acetic acid to the DMB sodium salt solution. The spherical agglomeration of DMB during the reactive crystallization in a batch crystallizer was monitored by real-time Particle Video Microscope (PVM). We found that the low feeding rate of acetic acid, high crystallization temperature, low agitation rate or adding seed crystal can facilitate the formation of spherical agglomerates. By using a simple model, the mean crystal agglomerate size of DMB thus predicted is generally in agreement with the experimental data. In addition, the crystallization process of DMB was optimized by a new control strategy of supersaturation to avoid disadvantages brought by agglomeration.

关键词： 5-(difluoromethoxy)-2-mercapto-1H-benzimidazole (DMB)     reactive crystallization     agglomeration     feeding rate     crystallization temperature     agitation rate    

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光电子晶体与全固态激光器及其应用——光电子技术发展的一个重大方向

许祖彦

《中国工程科学》 1999年 第1卷 第2期   页码 72-77

摘要：

光电子时代是微电子技术、激光技术、材料科学等高速发展、综合集成的产物。20世纪90年代光电子晶体的长足进步和大功率半导体激光技术的突破，导致全固态激光器的实用化，这将促使光电子技术在21世纪前50年对更多的国家支柱产业作出重大贡献，如先进制造业的材料加工、信息业的光存储、娱乐业的激光显示、能源业的激光核聚变电站和核裂变燃料生产、军工业的激光武器升级换代等。

关键词： 光电子晶体     全固态激光器     材料加工     光存储     激光显示     激光核聚变    

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Realization of energy-saving glass using photonic crystals

Yen-Hsiang CHEN, Li-Hung LIAO, Yu-Bin CHEN

《能源前沿（英文）》 2018年 第12卷 第1期   页码 178-184 doi: 10.1007/s11708-018-0523-9

摘要： This work successfully developed an energy-saving glass with wavelength selectivity. The glass is composed of a SiO substrate and two layers of three-dimensional photonic crystals. Each crystal is composed of identical and transparent polystyrene spheres after their self-assembling. The glass then possesses dual photonic band gaps in the near-infrared region to suppress penetration of thermal radiation. Experimental results show that the energy-saving glass decreases temperature increment in a mini-house. Moreover, the temperature after thermal equilibrium is lower than that inside a counterpart using ordinary glass.

关键词： energy-saving glass     photonic crystals     polystyrene spheres     self-assembly    

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Reactivity of triacetone triperoxide and diacetone diperoxide: Insights from nuclear Fukui function

Matthew J. SWADLEY, Panpan ZHOU, Tonglei LI

《化学科学与工程前沿（英文）》 2015年 第9卷 第1期   页码 114-123 doi: 10.1007/s11705-015-1507-5

摘要： Triacetone triperoxide (TATP) is more sensitive than diacetone diperoxide (DADP) in the solid-state explosion. To explain this reactivity difference, we analyzed the electronic structures and properties of the crystals of both compounds by using method to calculate the structures of their individual molecules as well as their lattice structures and particularly calculating Nuclear Fukui function to gain insight into the sensitivity of the initial, rate-determining step of their decomposition. Our results indicate that TATP and DADP crystal structures exhibit significantly different electronic properties. Most notably, the electronic structure of the TATP crystal shows asymmetry among its reactive oxygen atoms as supported by magnitudes of their nuclear Fukui functions. The greater explosion sensitivity of crystalline TATP may be attributed to the properties of its electronic structure. The electronic calculations provided valuable insight into the decomposition sensitivity difference between TATP and DADP crystals.

关键词： nuclear Fukui function     electronic perturbation     Hellmann-Feynman force     organic crystals     unimolecular decomposition    

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基于5 μm厚向列相液晶的高效圆极化相控阵系统的设计、校准和实验验证 Article

Xin Yu Wu,Fengshuo Wan,Hongyuan Feng,Shichao Jin,Chong Guo,Yu Wei,Dunge Liu,Yuqian Yang,Longzhu Cai,Zhi Hao Jiang,Wei Hong

《工程（英文）》 2024年 第32卷 第1期   页码 70-82 doi: 10.1016/j.eng.2023.08.013

摘要：

This paper presents a systematic investigation and demonstration of a K-band circularly polarized liquid-crystal-based phased array (LCPA), including the design, over-the-air (OTA) in-array calibration, and experimental validation. The LCPA contains 16 phase-shifting radiating channels, each consisting of a circularly polarized stacked patch antenna and a liquid-crystal-based phase shifter (LCPS) based on a loaded differential line structure. Thanks to its slow-wave properties, the LCPS exhibits a maximum phase-shifting range of more than 360° with a figure of merit of 78.3°·dB−1 based on a liquid crystal layer with a thickness of only 5 μm. Furthermore, an automatic OTA calibration based on a state ergodic method is proposed, which enables the extraction of the phase–voltage curve of every individual LCPA channel. The proposed LCPA is manufactured and characterized with a total profile of only 1.76 mm, experimentally demonstrating a scanned circularly polarized beam from −40° to +40° with a measured peak gain of 12.5 dBic and a scanning loss of less than 2.5 dB. The bandwidth of the LCPA, which satisfies the requirements of port reflection (|S11|) < −15 dB, an axial ratio (AR) < 3 dB, beam squinting < 3°, and a gain variation < 2.2 dB, spans from 25.5 to 26.0 GHz. The total efficiency is about 34%, which represents a new state of the art. The use of the demonstrated low-profile LCPA to support circularly polarized scanning beams, along with the systematic design and calibration methodology, holds potential promise for a variety of millimeter-wave applications.

关键词： Circularly polarized     Liquid crystal     Liquid-crystal-based phased array (LCPA)     Phase shifter     Over-the-air (OTA) calibration    

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and crack-free surface fabrication techniques for ultra-precision fly cutting of large-aperture KDP crystals

F. H. ZHANG, S. F. WANG, C. H. AN, J. WANG, Q. XU

《机械工程前沿（英文）》 2017年 第12卷 第2期   页码 193-202 doi: 10.1007/s11465-017-0448-8

摘要：

Large-aperture potassium dihydrogen phosphate (KDP) crystals are widely used in the laser path of inertial confinement fusion (ICF) systems. The most common method of manufacturing half-meter KDP crystals is ultra-precision fly cutting. When processing KDP crystals by ultra-precision fly cutting, the dynamic characteristics of the fly cutting machine and fluctuations in the fly cutting environment are translated into surface errors at different spatial frequency bands. These machining errors should be suppressed effectively to guarantee that KDP crystals meet the full-band machining accuracy specified in the evaluation index. In this study, the anisotropic machinability of KDP crystals and the causes of typical surface errors in ultra-precision fly cutting of the material are investigated. The structures of the fly cutting machine and existing processing parameters are optimized to improve the machined surface quality. The findings are theoretically and practically important in the development of high-energy laser systems in China.

关键词： ultra-precision fly cutting     large-aperture KDP crystals     spatial frequency     processing error    

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标题 作者 时间 类型 操作

Acoustic fault signal extraction via the line-defect phononic crystals

期刊论文

中国功能晶体研究进展

王继扬,于浩海,吴以成,Robert Boughton

期刊论文

Existence of complete band gaps in 2D steel-water phononic crystal with square lattice

Cunfu HE, Huanyu ZHAO, Ruiju WEI, Bin WU

期刊论文

Synthesis of crystals and particles by crystallization and polymerization in droplet-based microfluidic

Jingtao WANG, Jin ZHANG, Junjie HAN,

期刊论文

Filtration ability of hollow fiber membrane for production of magnesium ammonium phosphate crystals by

H. Watamura, H. Marukawa, I. Hirasawa

期刊论文

Control of the agglomeration of crystals in the reactive crystallization of 5-(difluoromethoxy)-2-mercapto

Yongli WANG, Shuyuan MA, Xiaodong Lü, Chuang XIE

期刊论文

光电子晶体与全固态激光器及其应用——光电子技术发展的一个重大方向

许祖彦

期刊论文

Realization of energy-saving glass using photonic crystals

Yen-Hsiang CHEN, Li-Hung LIAO, Yu-Bin CHEN

期刊论文

Han Huang：Deformation and Removal of Semiconductor and Laser Crystals at Extremely Small Scales（2019年

2021年04月23日

会议视频

Reactivity of triacetone triperoxide and diacetone diperoxide: Insights from nuclear Fukui function

Matthew J. SWADLEY, Panpan ZHOU, Tonglei LI

期刊论文

基于5 μm厚向列相液晶的高效圆极化相控阵系统的设计、校准和实验验证

Xin Yu Wu,Fengshuo Wan,Hongyuan Feng,Shichao Jin,Chong Guo,Yu Wei,Dunge Liu,Yuqian Yang,Longzhu Cai,Zhi Hao Jiang,Wei Hong

期刊论文

and crack-free surface fabrication techniques for ultra-precision fly cutting of large-aperture KDP crystals

F. H. ZHANG, S. F. WANG, C. H. AN, J. WANG, Q. XU

期刊论文