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Particle tunnels across the horizon of Garfinkle-Horowitz-Strominger dilaton black hole

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Science China(physics,Mechanics & Astronomy) 2007年第5期50卷 601-610页

作者： FANG HengZhong1 & ZHAO Zheng2.1 department of physics, China {2. of Petroleum, Dongying 2.7061, China 2.department of physics, beijing Normal {2., beijing 100875, China department of physics China University of Petroleum Dongying 257061 China department of physics Beijing Normal University Beijing 100875 China

We promote the work of Parikh and Wilczek on the black hole radiation to the emission of massive and charged particles from Garfinkle-Horowitz-Strominger black hole. The energy and charge of the space-time are conservational during the course of the evaporation. The calculation shows that the emission spectrum is not precisely thermal, while has a correction, and the conclusion supports the view- point of information conservation.

关键词： Hawking radiation, black body spectrum, barrier, information loss, entropy of black hole, Komar energy

KTN thin films prepared by pulsed laser deposition on transparent single crystal quartz(100)

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Science China(physics,Mechanics & Astronomy) 2005年第1期48卷 33-43页

作者： WANG Xiaodong, PENG Xiaofeng & ZHANG Duanming Laboratory of Phase Change and Interfacial Transport Phenomena, department of Thermal Engineering, tsinghua university,{2., China department of physics, Huazhong university of Science and Technology, Wuhan 430074, China 1. Laboratory of Phase Change and Interfacial Transport Phenomena Department of Thermal Engineering Tsinghua University 100084 Beijing China 2. department of physics Huazhong University of Science and Technology 430074 Wuhan China

Using the Sol-Gel method to produce the KTN ultrafine powder and the sintering technique with K2. atmosphere to prepare KTN ceramics as the targets instead of the KTN single crystal, highly oriented KTN thin films were produced on the transparent single crystal quartz (100) by the pulsed laser deposition (PLD). Since the thermal stress sustained by the quartz is relatively small, the limit temperature of the quartz substrates(300℃) is much lower than that of the P-Si substrates (560℃); the prepared thin film is at amorphous state. Increasing the pulsed laser energy density in the process incorporated with annealing the film after deposition at different temperatures converts the amorphous films into crystal. The optimal pulsed laser energy density and annealing temperature were 2.0 J/cm2.and 600℃, respectively. A discussion was made to understand the mechanism of film production at relatively low substrate temperature by PLD and effects of the annealing temperatures on the forming of the perovskite phase, and optimal conditions for the orientation of the crystal grain.

关键词： PLD technology, KTN thin film, single crystal quartz, pulsed energy density, annealing, perovskitephase.

CO_2.Mitigation in Coal Gasification Cogeneration Systems with Integration of the Shift Reaction, CO_2.Absorption and Methanol Production

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Journal of Thermal Science 2004年第3期13卷 193-198页

作者： Yuanyuan DUAN Jin ZHANG Key Laboratory of Thermal Science and Power Engineering, department of Thermal Engineering, tsinghua university,{2., China Key Laboratory of Thermal Science and Power Engineering Department of Thermal Engineering Tsinghua University Beijing China

Cogeneration of electricity and liquid fuel can achieve higher efficiencies than electricity generation alone in Integrated Gasification Combined Cycle (IGCC), and cogeneration systems are also expected to mitigate CO2.emissions. A proposed methanol-electricity cogeneration system was analyzed in this paper using exergy method to evaluate the specified system. A simple cogeneration scheme and a complicated scheme including the shift reaction and CO2.removal were compared. The results show that the complicated scheme consumes more energy, but has a higher methanol synthesis ratio with partial capture of *** those methanol and electricity cogeneration systems, the CO2.mitigation is not merely an additional process that consumes energy and reduces the overall efficiency, but is integrated into the methanol production.

关键词： cogeneration system methanol synthesis CO2 mitigation exergy analysis

Degradation of 4-chlorophenol in aqueous solution by γ-radiation and ozone oxidation

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Science China Chemistry 2006年第2期49卷 186-192页

作者： HU Jun1, WANG Jianlong1,2.& CHEN Rong1 1. Laboratory of Environmental Technology, Institute of Nuclear Energy Technology, tsinghua university, beijing 100084, China 2. State Key Joint Laboratory of Environmental Simulation and Pollution Control, tsinghua university, beijing 100084, China Correspondence should be addressed to Wang Jianlong 1. Laboratory of Environmental Technology Institute of Nuclear Energy Technology Tsinghua University Beijing 100084 China 2. State Key Joint Laboratory of Environmental Simulation and Pollution Control Tsinghua University Beijing 100084 China

The degradation of 4-chlorophenol (4-CP) by using gamma rays generated by a 60Co source in the presence of O3 was investigated. The radiolysis of 4-CP and the kinetics of 4-CP min-eralization were analyzed based on the determination of total organic carbon (TOC). The influence of initial 4-CP concentration and the free radicals scavengers (such as NaHCO3 and t-butanol) on the 4-CP degradation was also studied. The results showed that when the radiation rate was 336 Gy·min?1, 4-chlorophenol at concentration of 10 mg·L?1 could be completely degraded at the radiation dose of 2.kGy. The degradation of 4-chlorophenol could be described by a first-order reaction model, the rate constant of 4-CP degradation by combined ozonation and radiation was 0.1016 min?1, which was 2.4 times higher than the sum of radiation (0.02.4 min?1) and ozonation (0.0137 min?1). It re-vealed that the combination of radiation and ozonation resulted in synergistic effect, which can re-markably increase the degradation efficiency of 4-CP.

关键词： radiolysis, 4-chlorophenol, priority pollutant, degradation, O3, synergistic effect, kinetics.

Experimental studies on removal of carbon dioxide by aqueous ammonia fine spray

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Science China(Technological Sciences) 2010年第1期53卷 117-122页

作者： NIU ZhenQi,GUO YinCheng & LIN WenYi department of Engineering Mechanics,School of Aerospace,tsinghua {2.,beijing 100084,China 1. department of Engineering Mechanics School of Aerospace Tsinghua University Beijing 100084 China

Experimental studies on carbon dioxide capture in a spray scrubber were carried *** spray of aqueous ammonia was used as CO2.*** of different operating and design parameters on CO2.removal efficiency including concentration of aqueous ammonia,liquid flow rate,total gas flow rate,initial temperature and concentration of carbon dioxide were investigated.

关键词： carbon dioxide aqueous ammonia absorption removal efficiency fine spray

Measurement of Mean Burst Period in WallTurbulence by Wavelet Analysis

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Communications in Nonlinear Science and Numerical Simulation 1999年第3期4卷 3-5页

作者： Li LI Chunxiao XU Zhaoshun ZHANG and Guialang CUI(department of Engineering Mechanics, tsinghua university,{2., China) department of Engineering Mechanics Tsinghua University Beijing 100084 China

IntroductionInwallturbulence,theejectionoflow-speedfluidfromthewallandthesweepofth***urst,andwhentheflowisbursting,therealwaysea... 详细信息

IntroductionInwallturbulence,theejectionoflow-speedfluidfromthewallandthesweepofth***urst,andwhentheflowisbursting,therealwaysea...

关键词： turbulence burst phenomena wavelet analysis

Comparison of fractal measures

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Science China Mathematics 2005年第11期48卷 1545-1553页

作者： QU Yanhui,WEN Shengyou & WEN Zhiying department of Mathematics,tsinghua {2.,beijing 100084,China department of Mathematics,Hubei {2., Wuhan 430062. China 1. department of Mathematics Tsinghua University 100084 Beijing China 2. department of Mathematics Hubei University 430062 Wuhan China

In this paper, the relationship between the s-dimensional Hausdorff measures and the g-measures in Rd is discussed, where g is a gauge function which is equivalent to ts and 0 < s≤d. It shows that if s=d, then Hg = c... 详细信息

In this paper, the relationship between the s-dimensional Hausdorff measures and the g-measures in Rd is discussed, where g is a gauge function which is equivalent to ts and 0 2.d and Pg = c3Pd on Rd, where constants c1, c2.and c3 are determined by where Wg, Cg and Pg are the g-Hausdorff, g-central Hausdorff and g-packing measures on Rd respectively. In the case 02.s|F and Pg|F = c3Ps|F, where the constants c1, c2.and c3 depend not only on g and s, but also on F. A criterion is presented for judging whether an s-set has the above properties.

关键词： gauge function Hausdorff measure central Hausdorff measure packing measure.

TWO-DIMENSIONAL SIMULATION OF FLOWS IN PLANE-WALL DIFFUSERS

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Journal of Hydrodynamics 1992年第4期4卷 43-53页

作者： Yuan Ming-shun department of Hydraulic Engineering,tsinghua {2.,beijing 100084,P.R.China

A numerical model has been developed for computing turbulent flow in plane-wall *** model solves the weakly compressible flow equations with the application of the Smagorinsky's subgrid-scale turbulence model and the boundary conditions of partial slip and no slip at the solid *** examples include two-dimensional calculations of unstalled and stalled flows in diffusers of small diverging angle,as well as transitory stall flow in a symmetric diffuser of 16°total *** the unstalled and stalled flows,the calculated pressure recovery and velocity profile are compared with experimental *** the transitory stall flow,the com- putational result shows the unsteady flow features including the vortex shedding and stall washout phenomena that have been experimentally observed.

关键词： diffuser turbulent flow separation transitory stall Large-eddy simulation

Effect of Coarse Aggregate Size on Relationship between Stress and Crack Opening in Normal and High Strength Concretes

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Journal of Materials Science & Technology 2005年第5期21卷 85-94页

作者： Jun ZHANG Qian LIU and Lin WANGDepaxtment of Civil Engineering, tsinghua university, beijing 100084, China department of Civil Engineering Tsinghua University Beijing 100084 China

Fine and coarse aggregates play an important role in the fracture of concrete. However, quantitative informationavailable on the effect of the coarse aggregate size on the fracture properties of concrete is still limited. In the presentpaper, the effect of coarse aggregate size (single grade of 5~10, 10~16, 16~2. and 2.~2. mm) on stress-crackopening (σ-ω) relation in normal and high strength concretes (compressive strength of 40 and 80 MPa, respectively)was studied. The investigation was based on three-point bending tests implemented by fictitious crack analysis. Theresult shows that coarse aggregate size and cement matrix strength significantly influence the shape of σ-ω *** a given total aggregate content, in normal strength concrete, smaller size of aggregate leads to a high tensilestrength and a sharp stress drop after the peak stress. The smaller the coarse aggregate, the steeper the σ-ω *** contrast, in high strength concrete, the effect of aggregate size on σ-ω relation almost vanishes. A similar σ-ωrelation is obtained for the concrete except for the case of 2.~2. mm coarse aggregate size. The stress drop afterthe peak stress is more significant for high strength concrete than that for normal strength concrete. Meanwhile, thesmaller the coarse aggregate size, the higher the flexural strength. Fracture energy and characteristic length increasewith increasing coarse aggregate size in both normal and high strength concretes.

关键词： Aggregate size Stress-crack opening relation Fracture energy Bending test