检索结果-南通市图书馆

Tunneling Through Black Rings

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2007年第5期47卷 835-842页

作者： ZHAO Liu Department of Physics,Nankai University,tianjin 300071,china Department of Physics Nankai University Tianjin 300071 China

Hawking radiation of black ring solutions to 5-dimensional Einstein-Maxwell-dilaton theory is analyzedby use of the Parikh-Wilczek tunneling *** get the correct tunneling amplitude and emission rate,we adoptand develop the Angheben-Nadalini-Vanzo-Zerbini covariant approach to cover the effects of rotation and electronicdischarge all at once,and the effect of back reaction is also taken into *** constitutes a unified approach tothe tunneling *** the first law of thermodynamics for black rings holds,the emission rate is proportionalto the exponential of the change of Bekenstein-Hawking *** calculation for black ring temperatures agreesexactly with the results obtained via the classical surface gravity method and the quasi-local formalism.

关键词： black ring radiation tunneling method

Effect of Sn^(4+) B-Site Substitution on the Microstructure and Dielectric Properties of Ba(Mg_(1/3)Ta_(2/3))O_3 Microwave Ceramics

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2005年第5期21卷 773-775页

作者： Shunhua WU Guoqing WANG, Shuang WANG and Dandan LIUInstitute of Electronics and Information Engineering, tianjin University, tianjin 300072, china Institute of Electronics and Information Engineering Tianjin University Tianjin 300072 China

The effect of Sn^4＋（BaSnO3） B-site substitution on the microstructure and dielectric properties of Ba（Mg1/3Ta2/3）O3 microwave ceramics was investigated. X-ray diffraction shows that a complex perovskite material Ba（Mg1/3Ta2/3）O3 was prepared. As Sn^4＋ content x increases in the （1-x） Ba（Mg1/3Ta2/3）O3-xBaSnO3 （x=0.00～0.20） system, the dielectric constant generally keeps unchanged, while TCF changes from positive to negative. Although the addition of Sn^4＋ reduces the ordering degree, Q f0 is still increased when the ceramics density increases. This trend implies that Q f0 of this system is mostly determined by ceramics density rather than ordering degree. After sintering at 1500℃ for 3 h, the system with x=0.15 was found to have excellent dielectric properties as follows：ε≈25, Q f0≥300,000 GHz at 7 GHz, TCF=-0.6×10^-6/℃.

关键词： Ba(Mg1/3Ta2/3)O3 Complex perovskite Microwave Dielectric properties

OBSERVATIONS ON DEFORMATION BEHAVIOR OF HIGH PERFORMANCE FIBERS BY POLARIZING OPTICAL MICROSCOPY

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2000年第1期18卷 81-86页

作者： Chang-fa Xiao Yu-feng Zhang Department of Materials Science, tianjin Institute of Textile Science and Technology, tianjin 300160, china 天津纺织工学院天津

By means of polarizing optical microscopy (POM), deformation behavior of four kinds of fibers, i.e, ultra high molecular weight polyethylene (UHMW-PE) fiber, polyvinyl alcohol (PVA) fiber, polyethylene terephthalate (PET) fiber, and wholly aromatic (rho-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid) copolyester [P(HBA/HNA)]/PET (ACPET blend) fiber, in axial compression, axial impacting, and bending was observed. In compression, kink bands formed at an angle of 55-60 degrees ro the fiber axis in 10-times-drawn UHMW-PE fiber, 75-80 degrees in 40-times-drawn sample, 80 degrees in PVA fiber, and 90 degrees in the ACPET blend fiber. In impacting and bending, band angles of UHMW-PE, PVA and PET fibers are nearly the same as those formed in compression, indicating that slip systems do not change. For any of the four kinds of fiber, band spacing exhibits great differences in compression, in impacting, and in bending, which may be attributed to the differences in the degrees of strain or stress concentration.

关键词： high performance fiber axial compression axial impacting bending

Real Time Correction and Evaluation of Nonlinear Errors in Single Frequency Interferometers

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Lasers 1999年第1期8卷 40-45页

作者： WANG Chunhai ZHANG Guoxiong (College of Precision Instrument and Optoelectronics Engineering, tianjin University, tianjin 300072, china) 天津大学精密仪器和光电工程学院天津

１ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｇｌｅｆｒｅｑｕｅｎｃｙｉｎｔｅｒｆｅｒｏｍｅｔｅｒｐｏｓｅｓｅｓｓｏｍｅｉｍｐｏｒｔａｎｔａｄｖａｎｔａｇｅｓ：ａｖａｉｌａｂｉｌｉｔｙｏｆｏｂｔａｉｎｉｎｇｅｘｔｒｅｍｅｌｙｓｔａ... 详细信息

１ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｇｌｅｆｒｅｑｕｅｎｃｙｉｎｔｅｒｆｅｒｏｍｅｔｅｒｐｏｓｅｓｅｓｓｏｍｅｉｍｐｏｒｔａｎｔａｄｖａｎｔａｇｅｓ：ａｖａｉｌａｂｉｌｉｔｙｏｆｏｂｔａｉｎｉｎｇｅｘｔｒｅｍｅｌｙｓｔａｂｌｅｆｒｅｑｕｅｎｃｙ，ｎｏｆｒ...

关键词： nonlinear errors laser interferometer error correction

An approach to 3D NURBS modeling of complex fault network considering its historic tectonics

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第5期16卷 546-553页

作者： ZHONG Denghua, LIU Jie and LI Mingchao (School of Civil Engineering, tianjin University, tianjin 300072, china) School of Civil Engineering Tianjin University Tianjin 300072 China

Fault disposal is a research area that presents difficulties in 3D geological modeling and visualization. In this paper, we propose an integrated approach to reconstructing a complex fault network (CFN). Based on the non-uniform rational B-spline (NURBS) techniques, fault surface was constructed, reflecting the regulation of its spatial tendency, and correlative surfaces were enclosed to form a fault body model. Based on these models and considering their historic tectonics, a method was put forward to settle the 3D modeling problem when the intersection of two faults in CFN induced the change of their relative positions. First, according to the relationships of intersection obtained from geological interpretation, we introduced the topological sort to determine the order of fault body construction and rebuilt fault bodies in terms of the order; then, with the disposal method of two intersectant faults in 3D modeling and applying the Boolean operation, we investigated the characteristic of faults at the intersectant part. An example of its application in hydropower engineering project was proposed. Its results show that this modeling approach can increase the computing efficiency while less computer memory is required, and it can also factually and objectively reproduce the CFN in the engineering region, which establishes a theoretical basis for 3D modeling and analysis of complex engineering geology.

关键词： fault network NURBS technique historic tectonics topological sort 3D modeling.

Effect of CO_2 laser sclerectomy with iridectomy on ocular hypertension in rabbits

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2011年第1期4卷 30-32页

作者： Zhi-Xiao Xue 1,3,Ying-Xin Li 2,3,Yan-Shan Xu 4,Jiu-Min Yang 1 1 Laser Medicine Laboratory of tianjin Medical University,tianjin 300070,china 2 Laser Medicine Laboratory,Biomedical Engineering Institute of Chinese Academy of Medical Sciences & Peking Union Medical College,tianjin 300192,china 3 Laser Medicine Technology Engineering Center of tianjin,tianjin 300192,china 4 Eye Center of tianjin Medical University,tianjin 300384,china Laser Medicine Laboratory of tianjin Medical University Tianjin 300070 China.

AIM:To evaluate the efficiency and safety of an optimized CO2 Laser glaucoma surgery system for laser sclerectomy with ***:Rabbit trials were performed to evaluate the efficiency and ***:IOP was significantly decreased in laser group compared with trabeculectomy group(P<0.05) from 7th postoperative day to 60th *** with trabeculectomy group,histopathology studies confirmed fewer complications and better effects were found in laser ***:CO2 laser sclerectomy with iridectomy is effective and safe in terms of IOP lowering.

关键词： CO2 laser glaucoma sclerectomy with irid-ectomy intraocular pressure histopathological examination

Effects of Cr_2O_3 doping on the electrical properties and the temperature stabilities of PZT binary piezoelectric ceramics

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2008年第4期27卷 362-366页

作者： LI Jianhua SUN Qingchi School of Electronic and Information and Engineering Tianjin University Tianjin 300072 China. School of Materials Science and Engineering Tianjin University Tianjin 300072 China

The ceramics with Pb1.04Zr0.52Ti0.48O3 ＋ z wt.% Cr2O3 were prepared using the traditional technique. The effects of Cr2O3 doping on the phase structure, the microstructure, and the electrical properties of ceramics were investigated. Meanwhile, the temperature stabilities of the resonant frequency （fx） were studied. The results showed that the △fr/fr,25℃ decreased with the addition of 0.2 wt.% - 0.8 wt.% Cr2O3 as compared with the undoped samples. The minimum value （-0.182%） of △fr/fr,25℃ was obtained for z = 0.6 wt.% Cr2O3 samples that sintered at 1260℃. The values of ε^τ33/ε0 = 1650, tanδ = 0.006, d33 = 328 pC/N, Kp = 0.63, Qm = 2300 were obtained when Cr2O3 was 0.6 wt.%, which exhibited more excellent piezoelectric properties than other compositions such as those with z = 0.2 wt.%, 0.4 wt.%, and 0.8 wt.%, but had a similar value as compared with the tmdoped samples. When the Cr2O3 additive increased, the Curie temperature moved toward low temperature and the changes of resonant frequency changed from positive to negative with increasing temperature.

关键词： ceramics piezoelectric properties temperature stability doping

COMBINED LEGENDRE SPECTRAL-FINITE ELEMENTMETHOD FOR THE TWO-DIMENSIONAL UNSTEADYNAVIER-STOKES EQUATION

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 1999年第5期17卷 495-508页

作者： Song-man He Cai-ping Yang(Department of Basic Courses, Civil Aviation University of china, tianjin 300300, china) 中国民用航空学院天津

A combined Legendre spectral-finite element approximation is proposed for solving two-dimensional unsteady Navier-Stokes equation. The artificial compressibility is used. The generalized stability and convergence are ... 详细信息

关键词： Navier-Stokes equation combined Legendre spectral-finite element approximation

Effects　of　Zn^（2＋）　on　root　growth，cell　division，and　nucleoli　of　Allium　cepa　L．

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 1996年第1期8卷 21-27页

作者： Liu Donghua Jiang Wusheng Wang Chunli (Department of Biology, tianjin Normal University,tianjin 300074,china)Zhai Lin (Xinhua High School , tianjin 300204,china)

The effects of different concentrations of Zn￣(2+)ion on root growth,cell division,and nucleoli of Allium cepa were studied. The test Zn￣(2+) ion concentration was made up from zinc sulphate (ZnSO4. 7H2O) ranging from 10￣(-7) to 10￣(-2) mol/L. The solutions were prepared in tap water (pH =6. 5).The results indicated that Zn￣(2+) could obviously inhibit root growth at concentrations from 10￣(-4)to 10￣(-2) mol/*** treated with zinc sulphate showed the presence of c-mitosis, anaphase bridges,including sticky and fluidized bridges (at 10￣(-3) to 10￣(-2) mol/L) , chromosome stickiness, irregularly shaped nuclei, broken nuclei and micronuclei. A toxicity effect was also observed on the nucleoli using silver staining technique after 48h of treatment with 10￣(-4)to 10￣(-2) mol/L Zn￣(2+), e. g,the nucleolar particulate material scattered around the nucleoli in the nucleus of root tip cells.

关键词： Allium cepa mitosis chromosome aberration nucleoli silver staining technique.