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PREDICTION OF ACOUSTIC PERFORMANCE IN EXPANSION CHAMBER MUFFLERS WITH MEAN FLOW BY FINITE ELEMENT METHOD

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Chinese Journal of Mechanical engineering 2003年第3期16卷 292-295,304页

作者： Liu YadongLi CongxinRuan Xueyunational Die & Mold CAD engineeringresearch center,Shanghai Jiaotong University,Shanghai 200030, China Shanghai Jiaotong University National Die & Mold CAD Engineering Research Center 上海 200030

The equation of wave propagation in a circular chamber with mean flow is obtained. Computational solution based on finite element method is employed to determine the transmission loss of expansive chamber. The effect of the mean flow and geometry (length of expansion chamber and expansion ratio)on acoustic attenuation performance is discussed, the predicted values of transmission loss of expansion chamber without and with mean flow are compared with those reported in the literature and they agree well. The accuracy of the prediction of transmission loss implies that finite element approximations are applicable to a lot of practical applications.

关键词： Wave equation Finite element method Exhaust mufflers Acoustic characteristics

Lactonization of dyes promoted by a coordination cage facilitates cavity-induced chromism as ion mobile detector

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Science China Chemistry 2024年第5期67卷 1554-1560页

作者： Liangliang Zhang Yu Liang Zhifeng Xiao Yuxuan Meng Jinyi Huang Xi Lin Ji Li Hong-Cai Zhou Yu Fang Strait Institute of Flexible Electronics(SIFE Future Technologies)Fujian Normal University and Strait Laboratory of Flexible Electronics(SLoFE)Fuzhou 350017China State Key Laboratory of Chemo/Bio-Sensing and Chemometrics College of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082China Department of Chemistry Texas A&M UniversityCollege StationTexas 77842-3012USA State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China Frontiers Science center for Flexible Electronics(FSCFE) MIIT Key Laboratory of Flexible Electronics(KLoFE)Northwestern Polytechnical UniversityXi’an 710072China

Dye molecules often change colors(so-called “chromism”) according to the environment variation. However, they are rarely induced by a catalytic amount of cavity. Through encapsulation in the cavity of a porous coordination cage(PCC-2), Rhodamine B(1) is transformed from red quinonoid form(1q) into colorless lactone form(1l) in aprotic polar solutions. The μ4-OH groups in the cavity of PCC-2 are shown to stabilize the uncommon zwitterion intermediate(1z), followed by converting to 1l, thus accelerating the equilibrium. The chromism is catalyzed by 0.25 mol% of PCC-2, and the reaction rate is improved by 80,400times. 1@PCC-2 can be further fabricated to a sol-gel that exhibits ion recognition properties. The resulting encapsulation and stabilization of an unconventional intermediate by a catalytic amount of the coordination cage provides fundamental insights into molecular isomerization and has potential use in chemical sensing.

关键词： porous coordination cage Zwitterion intermediate cavity Rhodamine B chromism

Deciphering the role of mtHOin hepatic ischemia-reperfusion injury mechanisms with low-background super-resolution fluorogenic probe

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Science China Chemistry 2024年

作者： Bin Fang Limin Wang Haoqin Li Jiaxin Zhang Yang Ding PanPan Li Bo Peng Hua Bai Lin Li Frontiers Science center for Flexible Electronics Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials&EngineeringNorthwestern Polytechnical University Institute of Flexible Electronics (IFE Future Technologies)Xiamen University

Hepatic ischemia-reperfusion injury（HIRI） is characterized by mitochondrial dysfunction and oxidative stress. Monitoring mitochondrial hydrogen peroxide（mtH2O2） levels in real-time through super-resolution imaging is crucial for elucidating its distribution in live cells and its mechanism of action during HIRI. However, low-background fluorogenic probes have been overlooked in the context of super-resolution imaging. In this study, we developed a low-background fluorogenic probe（MitoWG） with the potential for super-resolution morphology-correlated mitochondrial identification to track the fluctuates of mtH2O2in HIRI. Activation of the desirable fluorescence properties of the probe by mtH2O2was confirmed using structural illumination microscopy（SIM）, enabling high-quality mitochondrial imaging with exceptional specificity and *** in mt H2O2levels were successfully observed in both cellular and rat models of HIRI. Furthermore, we associated the decline in mitochondrial redox homeostasis with accelerated mtH2O2production during HIRI, which triggered mitophagy deficiency and led to cell death. In conclusion, Mito-WG possesses excellent photophysical and low-background properties for SIM imaging, making it a promising tool for mtH2O2tracking in HIRI research and clinical diagnosis.

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Structure and magnetic properties of TbCu_7-type melt-spun Sm–Fe–B alloys

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Rare Metals 2019年第2期38卷 151-156页

作者： Chuan-Jiang Zheng Yang Luo Dun-Bo Yu Wen-Long Yan Hong-Wei Li Yong-Jun Mao Shuo Lu Ning-Tao Quan national engineering research center for Rare Earth Materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd.

The melt-spun SmFe_(12)B_x(x = 0, 0.50, 0.75,1.00, 1.25 and 1.50) ribbons were prepared at 40 m·s^(-1),and their structure and magnetic properties were studied by powder X-ray diffraction(XRD), vibrating sample magnetometer(VSM) and transmission electron microscopy(TEM). XRD results indicate that SmFe_(12)B_x alloys with 0.50 ≤ x ≤ 1.00 are composed of single-phase TbCu_7-type structure. Moreover, it is found that the boron addition can inhibit the emergence of soft magnetic phase a-Fe and result in the increase in the axial ratio c/a. After annealing at 650 ℃ for 0.5 h, the metastable phase TbCu_7 initially decomposes into the stable phase Sm_2Fe_(14)B(Nd_2Fe_(14)B-type) and a-Fe. The value of magnetic moment per Fe atom increases slightly from 1.75 uB for boron-free sample to 1.80 uB for the x = 0.75 sample and then decreases *** addition, the best magnetic properties of maximum energy product [(BH)_(max)] of 14.56 kJ·m^(-3), coercivity(H_(cj))of 172.6 kA·m^(-1) and remanence(B_r) of 0.45 T are obtained for the SmFe_(12)B_(1.00) alloy. Based on transmission electron microscopy(TEM) results, the average size of grains is around 197 nm for B-free sample and decreases to 95 nm for x = 1.00 sample, indicating that the addition of boron can refine grains.

关键词： TbCu7-type structure Sm-Fe-B ribbons Phase formation Magnetic moment Microstructure

Effects of precursor moisture and inert N_2 atmosphere calcinations on structure and properties of alumina modified CeZrLaNd mixed oxides

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Journal of Rare Earths 2019年第6期37卷 609-616页

作者： Meisheng Cui Zhizhe Zhai Hao Wang Yongke Hou Yongqi Zhang Xiaowei Huang national engineering research center for Rare Earth Materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd.

CeO_2-ZrO_2 mixed oxides are widely used in the three-way catalysts due to their unique reversible oxygen storage and release capacity. Large surface area, high oxygen storage capacity and good thermal stability of cerium zirconium mixed oxides are the key properties for the automotive catalysts so as to meet the strict emission regulations. In this work, alumina modified CeZrLaNd mixed oxides were prepared by a co-precipitation method. The effects of moisture in precursor and inert N2 atmosphere during calcinations on the structure and properties were investigated by Brunauer-Emmett-Teller(BET) surface area measurements, X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), hydrogen temperature-programmed reduction(H_2-TPR), oxygen storage capacity(OSC), Raman spectroscopy, and X-ray photoelectron spectroscopy(XPS). The results show that the moisture in precursor during calcinations increases the crystal grain size of the cerium zirconium mixed oxides, improving the thermal stability. And the aged surface area of sample after being calcined at1000 ℃ for 4 h reaches 68.8 m^2/g(5.7% increase compared with the common sample). The inert N2 atmosphere endows a great pore-enlarging effect, which leads to high fresh surface area of 148.9 m2/g(13.5% increase compared with the common sample) and big pore volume of 0.5705 mL/g. The redox and oxygen storage capacity are also improved by inert N2 atmosphere with high OSC value of 241.06μmolO_2/g(41.3% increase compared with the common calcination), due to the abundant formation of the crystal defects and oxygen vacancies.

关键词： Precursor moisture Inert N2 atmosphere Calcinations Alumina modified CeZrLaNd mixed oxides Rare earths

Effect of structural parameters of Gaussian repaired pit on light intensity distribution inside KH_2PO_4 crystal

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Chinese Physics B 2014年第8期23卷 540-547页

作者：肖勇陈明君程健廖威王海军李明全 center for Precision engineering Harbin Institute of Technology Chengdu Fine Optical engineering research center

KH2PO4 （KDP） crystal with excellent optical properties is a very important element of inertial confinement fusion （ICF） device. However, KDP crystal surface micro-defects severely reduce the crystal laser damage threshold, affecting the crystal service life. In this paper, Gaussian repaired pit is used to replace the crystal surface micro-defects, in order to improve the laser damage resistance of the KDP crystal with surface micro-defects. At first, the physical model of Gaussian repaired pit is built by Fourier model method, and the accuracy of the method is analyzed. It is found that the calculation error can be reduced by increasing the product of the width-period ratio and the truncation constant of the repaired pit. The calculation results about the physical model of Gaussian repaired pit show that the light intensity distribution within the crystal is symmetrical, and there are evidently enhanced light intensity regions in the crystal. Meanwhile, the maximum relative intensity inside the KDP crystal decreases gradually with the increase of the width of the Gaussian repaired pit. Secondly, the Gaussian repaired pits with different widths and the same depth of 20 μm are processed by micro-milling. Their surfaces are very smooth and present the ductile cutting state under the microscope. Finally, the laser damage threshold of the Gaussian repaired pits on the surface of the KDP crystal sample is measured by a 3 ω, 6-ns laser. The results showthat the maximum threshold of the Gaussian repaired pits is 3.12 J/cm2, which is 60% higher than the threshold of initial damage point, and the laser damage threshold increases with the increase of the width of the Gaussian repaired pit.

关键词： KH2PO4 Gaussian repaired pit Fourier modal method laser damage threshold

Degradation of Synthetic Dyeing Wastewater by Underwater Electrical Discharge Processes

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Plasma Science and Technology 2013年第7期15卷 659-665页

作者： S.D.KIM D.I.JANG B.J.LIM S.B.LEE Y.S.MOK Yeongsan River Environment research center National Institute of Environmental ResearchGwangju 500-480 Korea Department of Chemical and Biological engineering Jeju National UniversityJeju 690-756 Korea

Electrical discharge treatments of synthetic dyeing wastewater were carried out with two different systems： underwater pulsed electrical discharge （UPED） and underwater dielectric barrier discharge （UDBD）. Reactive Blue 4 （RB4） and Acid Red 4 （AR4） were used as model contaminants for the synthetic wastewater. The performance of the aforementioned systems was compared with respect to the chromaticity removal and the energy requirement. The results showed that the present electrical discharge systems were very effective for degradation of the dyes. The dependences of the dye degradation rate on treatment time, initial dye concentration, electrical energy, and the type of working gas including air, 02, and N2 were examined. The change in the initial dye concentration did not largely affect the degradation of either RB4 or AR4. The energy delivered to the UPED system was only partially utilized for generating reactive species capable of degrading the dyes, leading to higher energy requirement than the UDBD system. Among the working gases, the best performance was observed with O2. As the degradation proceeded, the concentration of total dissolved solids and the solution conductivity kept increasing while pH showed a decreasing trend, revealing that the dyes were effectively mineralized.

关键词： degradation dyeing wastewater pulsed electrical discharge dielectric barrierdischarge

Microstructure,Mechanical Properties,and Corrosion Behavior of Mg-Al-Ca Alloy Prepared by Friction Stir Processing

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Acta Metallurgica Sinica(English Letters) 2022年第5期35卷 703-713页

作者： Wen Wang Shan-Yong Chen Ke Qiao Pai Peng Peng Han Bing Wu Chen-Xi Wang Jia Wang Yu-Hao Wang Kuai-She Wang School of Metallurgical engineering National and Local Joint Engineering Research Center for Functional Materials ProcessingXi’an University of Architecture and TechnologyXi’an710055China

Friction stir processing(FSP)was used to modify the microstructure and improve the mechanical properties and corrosion resistance of an Mg-Al-Ca *** results demonstrated that,after FSP,the grain size of the Mg-Al-Ca alloy was decreased from 13.3 to 6.7μ***,the Al_(8)Mn_(5) phase was broken and dispersed,and its amount was *** yield strength and ultimate tensile strength of the Mg-Al-Ca alloy were increased by 17.0%and 10.1%,respectively,due to the combination of fine grain,second phase,and orientation strengthening,while the elongation was slightly *** immersion and electrochemical corrosion rates in 3.5 wt%NaCl solution decreased by 18.4%and 37.5%,respectively,which contributed to grain ***,the stress corrosion cracking(SCC)resistance of the modified Mg-Al-Ca alloy decreased significantly,which was mainly due to the filiform corrosion induced by the Al_(8)Mn_(5) *** was mainly controlled by anodic dissolution,while the cathodic hydrogen evolution accelerated the SCC process.

关键词： Friction stir processing Mg-Al-Ca alloy Second phase Mechanical properties Stress corrosion cracking

Synthesis and photoluminescence properties of octahedral K_2(Ge,Si)F_6:Mn^(4+) red phosphor for white LED

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Journal of Rare Earths 2016年第12期34卷 1173-1178页

作者：金玉明刘荣辉陈观通刘元红马小乐邵冷冷王磊 national engineering research center for Rare Earth Materials General Research Institute for Nonferrous Metalsand Grirem Advanced Materials Co.Ltd.

A novel red-emitting K2（Ge,Si）F6：Mn^4＋ phosphor with uniform morphology was synthesized by co-precipitation method. The pure K2GeF6 phase with P63 mc space group other than P3m1 space group was affirmed just by incorporation of Si in K2GeF6 at room temperature according to XRD characterization. SEM images showed lamellar and octahedron grain morphology for K2GeF6：Mn^4＋ and K2（Ge,Si）F6：Mn^4＋ phosphors, respectively. It was also found that the photoluminescence excitation（PLE） and photoluminescence（PL） showed slight displacement in K2GeF6：Mn^4＋ and K2（Ge,Si）F6：Mn^4＋ system. And the zero-phonon line（ZPL） of the PL spectrum of K2GeF6：Mn^4＋ with Si showed a strong peak. Meanwhile crystalline field surrounding Mn^4＋ changes could affect the decay time in this fluoride system. The color gamut of the LED devices based on K2（Ge,Si）F6：Mn^4＋ and K2GeF6：Mn^4＋ reached up to 94.58% NTSC（national Television Standards Committee） and 94.386% NTSC, respectively, that was much higher than that based on nitride red phosphors. All these original characteristics in K2（Ge,Si）F6：Mn^4＋ phosphor are desirable for potential applications as a red phosphor for improving lighting and display quality of conventional white LEDs.

关键词： K2(Ge Si)F6:Mn4+ fluoride PLE and PL decay time phosphors rare earths