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Determination of surfac. struc.ure and the depth profile of silic. glass by infrared spec.rosc.py

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光学精密工程 2005年第4期13卷 413-420页

作者： c. z. Tan Laboratory of Solid State Mic.ostruc.ure and Department of Materials Sc.enc. and Engineering Nanjing University 210093 Nanjing China Institut für Mineralogie Freie Universitt Berlin 14195 Berlin Germany

The surfac. struc.ure and properties are different from those of the bulk, depending on the substrate materials and deposition c.ndition, and playing an important role in prec.se optic.l c.mponents. The c.nventional spec.rosc.pic.methods to monitor the surfac. struc.ure are restric.ed only in several layers of molec.les. It is known that the penetration depth of the inc.dent light inc.eases with its wavelength and dec.eases with the angle of inc.denc.. Thus infrared spec.rosc.py provides a powerful means for determination of surfac. struc.ure and the depth profile up to mic.ometers. By rec.rding the reflec.ion spec.ra at different angles of inc.denc., the surfac. struc.ure and its depth profile c.n be monitored suc.essively. Further, the inc.dent field has the subc.mponents parallel and perpendic.lar to the surfac., whic. exc.te the transverse and longitudinal optic.modes, respec.ively. c.ange of the polariz.tion direc.ion of the inc.dent light provides a prac.ic.l func.ion to study anisotropic.property of the surfac. and the interac.ion between the transverse and longitudinal optic.modes. In this work, infrared spec.rophotometer was applied to investigate the depth profile in mic.ostruc.ure of silic. glass. c.mbining with the glass fiber system, this tec.nique c.n be used for in-situ c.ntrol of the deposition proc.ss. In c.mparing with ellipsometry, this method reveals both struc.ural and c.nstitutional information.

关键词：硅石光谱红外线表面结构光学材料

Numeric.l investigation on the flowfield of “swallowtail” c.vity for supersonic.mixing enhanc.ment

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Ac.a Mec.anic. Sinic. 2009年第1期25卷 37-44页

作者： c. Wang z. Jiang z. Hu J. Lu Institute or Mec.anic.. c.inese Ac.demy of Sc.enc.s 100190 Beijing China Rec.PT Gyeongsang National University JinjuKyeongnam 660-701 South Korea

A ＂swallowtail＂ c.vity for the supersonic.c.mbustor was proposed to serve as an effic.ent flame holder for sc.amjets by enhanc.ng the mass exc.ange between the c.vity and the main flow. A numeric.l study on the ＂swallow- tail＂ c.vity was c.nduc.ed by solving the three-dimensional Reynolds-averaged Navier-Stokes equations implemented with a k-e turbulenc. model in a multi-bloc. mesh. Turbu- lenc. model and numeric.l algorithms were validated first, and then test c.ses were c.lc.lated to investigate into the mec.anism of c.vity flows. Numeric.l results demonstrated that the c.rtain mass in the supersonic.main flow was suc.ed into the c.vity and moved spirally toward the c.mbustor walls. After that, the flow went out of the c.vity at its lateral end, and finally was effic.ently mixed with the main flow. The c.mparison between the ＂swallowtail＂ c.vity and the c.nventional one showed that the mass exc.anged between the c.vity and the main flow was enhanc.d by the lateral flow that was induc.d due to the pressure gradient inside the c.vity and was driven by the three-dimensional vortex ring generated from the ＂swallowtail＂ c.vity struc.ure.

关键词： Supersonic.mixing - Flame holder "Swallowtail" c.vity - c.mbustion ignition Numeric.l simulation

Wavelet-Based Mixed-Resolution c.ding Approac. Inc.rporating with SPT for the Stereo Image

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Journal of Systems Engineering and Elec.ronic. 2001年第3期12卷 39-44页

作者： Xu, c. z.ang, z. An, P. c.mmunic.tion Sc.ool Shanghai University Shanghai 200072 China

With the advanc.s of display tec.nology, three-dimensional(3-D) imaging systems are bec.ming inc.easingly popular. One way of stimulating 3-D perc.ption is to use stereo pairs, a pair of images of the same sc.ne ac.uired from different perspec.ives. Sinc. there is an inherent redundanc. between the images of a stereo pairs, data c.mpression algorithms should be employed to represent stereo pairs effic.ently. The proposed tec.niques generally use bloc.-based disparity c.mpensation. In order to get the higher c.mpression ratio, this paper employs the wavelet-based mixed-resolution c.ding tec.nique to inc.rporate with SPT-based disparity-c.mpensation to c.mpress the stereo image data. The mixed-resolution c.ding is a perc.ptually justified tec.nique that is ac.ieved by presenting one eye with a low-resolution image and the other with a high-resolution image. Psyc.ophysic.l experiments show that the stereo image pairs with one high-resolution image and one low-resolution image provide almost the same stereo depth to that of a stereo image with two high-resolution images. By c.mbining the mixed-resolution c.ding and SPT-based disparity-c.mpensation tec.niques, one referenc. (left) high-resolution image c.n be c.mpressed by a hierarc.ic.l wavelet transform followed by vec.or quantiz.tion and Huffman enc.der. After two level wavelet dec.mpositions, for the low-resolution right image and low-resolution left image, subspac. projec.ion tec.nique using the fixed bloc. siz. disparity c.mpensation estimation is used. At the dec.der, the low-resolution right subimage is estimated using the disparity from the low-resolution left subimage. A full-siz. rec.nstruc.ion is obtained by upsampling a fac.or of 4 and rec.nstruc.ing with the synthesis low pass filter. Finally, experimental results are presented, whic. show that our sc.eme ac.ieves a PSNR gain (about 0.92dB) as c.mpared to the c.rrent bloc.-based disparity c.mpensation c.ding tec.niques.

关键词： Data reduc.ion Dec.ding Image c.ding Image c.mpression Image rec.nstruc.ion Imaging tec.niques Motion c.mpensation Motion estimation Optic.l resolving power Projec.ion systems Stereo vision Wavelet transforms

Passive Q-switc.ing in an erbium-doped fiber laser using tungsten sulphoselenide as a saturable absorber

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c.inese Optic. Letters 2018年第2期16卷 69-73页

作者： H.Ahmad z.c.tiu S.I.Ooi Photonic. Researc. c.ntre University of Malaya

A highly stable Q-switc.ed laser inc.rporating a mec.anic.lly exfoliated tungsten sulphoselenide （WSSe） thin sheet saturable absorber （SA） is proposed and demonstrated. The SA assembly, formed by sandwic.ing a thin WSSe sheet between two fiber ferrules within the erbium-doped fiber laser, is used to effec.ively modulate the laser c.vity losses. The WSSe-based SA has a saturation intensity of ~0.006 MW∕c.^2 and a modulation depth of 7.8%, giving an optimum Q-switc.ed laser output with a maximum repetition rate of 61.81 kHz.and a minimum pulse width of 2.6 μs. The laser＇s highest output power of 0.45 mW and highest pulse energy of 7.31 nJ are ac.ieved at the maximum pump power of 280.5 mW. The tunability of the c.vity＇s output at the maximum pump power is analyz.d with a c.band tunable bandpass filter, giving a broad tunable range of ~40 nm, from 1530 nm to 1570 nm. The output performanc. of the tunable Q-switc.ed laser c.rrelates well with the gain spec.rum of erbium-doped fibers, with the shift in the gain profile as a result of the saturated SA.

关键词： Passive Q-switc.ing in an erbium-doped fiber laser using tungsten sulphoselenide as a saturable absorber SA EDF

Numeric.l Modeling and Analysis of Grooved Surfac. Applied to Film c.oling

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Journal of Bionic.Engineering 2011年第4期8卷 464-473页

作者： L. Guo z. c. Liu Y. Y. Yan z. W. Han Fac.lty of Engineering University of Nottingham Nottingham NG7 2RD UK Department of Internal c.mbustion Engine Jilin University Changchun 130022 P. R. China Key Laboratory of Bionic.Engineering （Ministry of Educ.tion China） Jilin University Changchun 130022 P. R. China

In order to improve the effic.enc. of film c.oling, numeric.l investigation was c.rried out to study the effec.s of different film-c.oled plates on surfac. heat transfer. Both grooved and non-grooved surfac.s were c.nc.rned. The modeling was per- formed using Fluent software with the adoption of Shear-Stress Transport （SST） k-ωmodel as the turbulenc. c.osure. The c.olant was supplied by a single film c.oling hole with an inc.ination angle of 30°. The Mac. numbers for the c.olant flow and the mainstream flow were fixed at 0 and 0.6, respec.ively. At three blowing ratios of 0.5, 1.0 and 1.5, the aerodynamic.behaviour of the mixing proc.ss as well as the heat transfer performanc. of the film c.oling were presented. The numeric.l results were validated using experimental data extrac.ed from a benc.mark test. Good agreements between numeric.l results and the ex- perimental data were observed. For the film c.oling effic.enc., it shows that both loc.l and laterally averaged c.oling effec.iveness c.n be improved by the non-smooth surfac. at different blowing ratios. Using the grooved surfac., the turbulenc. intensity upon the plate c.n be reduc.d notably, and the mixing between the two flows is weakened due to the reduc.d turbu lenc. level. The results indic.te that the c.oling effec.iveness of film c.oling c.n be enhanc.d by applying the grooved surfac..

关键词： film c.oling non-smooth surfac. c.oling effec.iveness grooved struc.ure blowing ratio

Tunable passively Q-switc.ed ytterbium-doped fiber laser with mec.anic.lly exfoliated GaSe saturable absorber

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c.inese Optic. Letters 2018年第2期16卷 93-97页

作者： H.Ahmad S.N.Aidit S.I.Ooi z.c.tiu Photonic. Researc. c.ntre University of Malaya

A tunable passively Q-switc.ed ytterbium-doped fiber laser using few-layer gallium selenide（GaSe） as a saturable absorber（SA） is *** few-layer GaSe SA,whic. is fabric.ted by the mec.anic.l exfoliation method,is able to generate a Q-switc.ed fiber laser that has a maximum repetition rate of 92.6 kHz.and a minimum pulsed width of 2.3 μ*** highest pulse energy exhibited by the generated pulse is 18.8 nJ with a signal to noise ratio of ~40 *** tunability of the proposed laser c.vers from 1042 to 1082 nm,giving a tuning range of 40 nm.

关键词： Tunable passively Q-switc.ed ytterbium-doped fiber laser with mec.anic.lly exfoliated GaSe saturable absorber SA

Revealing the high-frequenc. attenuation mec.anism of polyurea-matrix c.mposites

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Ac.a Mec.anic. Sinic. 2020年第1期36卷 130-142页

作者： J.c.eng z.L.Liu c.c.Luo T.Li z.J.Li Y.Kang z.z.uang Applied Mec.anic. Laboratory School of Aerospace EngineeringTsinghua UniversityBeijing100084China Key Laboratory of Advanc.d Materials of Ministry of Educ.tion Department of Chemical EngineeringTsinghua UniversityBeijing100084China Sc.ool of Materials Sc.enc. and Engineering Tsinghua UniversityBeijing100084China

In this paper,a method for analyz.ng the high-frequenc. attenuation property of polyurea-matrix c.mposites is developed by c.mbining experimental,c.mputational and theoretic.l ***,the ultrasonic.experimental platform is established by solving the diffic.lties of high-frequenc. ultrasonic.testing as high-frequenc. signal distortion,insuffic.ent driving voltage and sampling rate failure,to study the dynamic.mec.anic.l properties(1-5 MHz.of pure polyurea and polyurea-matrix ***,the influenc.s of c.mposite parameters inc.uding the siz. and volume frac.ion of inc.usions on wave attenuation performanc. under different frequenc.es are obtained and further verified by numeric.l ***,the c.ntribution of inc.usions to the wave attenuation performanc. is also theoretic.lly *** is found that the inc.ease of inc.usion volume frac.ion and inc.usion diameter will inc.ease the attenuation c.effic.ent of the *** the attenuation of c.mposites with the inc.usions of a 150-μm diameter and 30%as volume frac.ion c.n be 82%higher than pure *** amplifying attenuation effec. of inc.usions is mainly attributed to the sc.ttering effec.,whic. is verified by c.mparing numeric.l and theoretic.l results.

关键词： Polyurea Visc.elastic Dynamic.mec.anic.l properties Ultrasound

Water solubility enhanc.ments of pyrene by single and mixed surfac.ant solutions

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Journal of Environmental Sc.enc.s 2001年第4期13卷 491-496页

作者： z.u, L.-z. c.iou, c.T. Department of Environmental Sc.enc. Zhejiang University Hangzhou 310028 China

Water solubility enhanc.ments of pyrene by both single-surfac.ant and mixed-surfac.ant solutions were c.mpared and evaluated. The solubility of pyrene in water was greatly enhanc.d by eac. of Triton X-100 (TX100), Triton X-405 (TX405), Brij 35 and SDS, in whic. the water solubility enhanc.ments inc.eased with inc.easing surfac.ant c.nc.ntrations. The extent of solubility enhanc.ments at surfac.ant c.nc.ntrations below. the c.c.is the order of TX100 > Brij 35 > TX405 > SDS; the sequenc. at surfac.ant c.nc.ntrations above the c.c.is TX100 > Brij 35 > SDS > TX405. Pyrene was solubiliz.d synergistic.lly by anionic.nonionic.mixed surfac.ant solutions, espec.ally at low surfac.ant c.nc.ntrations. The synergistic.power of the mixed surfac.ants is SDS-TX405 > SDS-Brij 35 > SDS-TX100. The synergism as noted is attributed to inc.easing Kmc.and/or dec.easing the c.c.of the mixed surfac.ant solution. For SDS-TX405 and SDS-Brij 35 mixed surfac.ant solutions, an inc.ease in Kmc.is c.upled with a dec.ease in the c.c. for SDS-TX100, only a dec.eased in the c.c.value is noted. Mixed-surfac.ant solutions may improve the performanc. of the surfac.ant-enhanc.d remediation (SER) of soils by inc.easing the bioavailability and biodegradation of non-aqueous-phase organic.pollutants and reduc.ng the level of surfac.ant pollution and remediation expenses.

关键词： Biodegradation c.nc.ntration (proc.ss) Solubility Water

High Temperature Oxidation and Wear Resistanc. of Y-modified Hot Dipping Aluminiz.d c.ating on Sc.12 Steel

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稀有金属材料与工程 2012年第S1期41卷 231-235页

作者： Fan, X. S. Yang, z. G. z.ang, c. Tsinghua Univ Dept Mat Sci & Engn State Key Lab New Ceram & Fine Proc Beijing 100084 Peoples R China

Mic.ostruc.ures,high-temperature oxidation and wear resistanc. of hot dipping Al-Si-Y c.ating on Sc.12 heat resistant c.st steel were investigated in this *** aluminiz.d c.ating was c.arac.eriz.d by sc.nning elec.ron mic.osc.py(SEM),energy dispersive X-ray spec.rometry(EDX)and X-ray diffrac.ion(XRD).The results showed that the c.ating was c.mposed of the Al-ric. outer layer and the intermetallic. inner *** the Al-ric. layer,some Y-ric. prec.pitates and Fe-Al-Si-c. prec.pitates c.uld be *** intermetallic. layer presented three layers induc.d by the inc.ease of Fe,c.,Ni c.ntent and the c.rresponding dec.ease of Al,Si *** oxidation tests were c.nduc.ed in still air at 850℃for up to 100 *** oxidation,a top oxide sc.le c.mposed of mainlyα-Al2O3,Al5Y3O12 was formed on the steel *** intermetallic. beneath the oxide sc.le c.nsisted of mainly FeAl and small amount of Fe2Al5 and c.3Si *** mass gain of the c.ated and unc.ated Sc.1steel is 0.45 mg/c. 2 and 0.57 mg/c. 2,*** wear resistanc. was investigated using a high-temperature pin-on-disc.tribometer at 650℃.The wear rate for the c.ated and unc.ated steel is 0.45μm 3 /μm.N and 3.01μm 3 /μm.N,*** high temperature wear tests and oxidation tests results demonstrated that the yttrium-modified aluminiz.d spec.men had signific.ntly improved high-temperature wear resistanc. and equivalent oxidation resistanc. c.mpared with the original Sc.12 spec.men.

关键词： hot dipping aluminiz.ng oxidation resistanc. high-temperature wear resistanc.