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| 1 | Mechanism and control of convective heat transfer——Coordination of velocity and heat flow fields显示文摘A second look has been given at the mechanism of convective heat transfer based on the analogy between convection and conduction with heat sources. The strength of convective heat transfer depends not only on the fluid velocity and fluid properties, but also on the coordination of fluid velocity and heat flow fields. Hence, based on the included angle of velocity and temperature gradient vectors, the presence of fluid motion may enhance or reduce heat transfer. With this concept, the known heat transfer phenomena may be understood in a deeper way. More important is that some novel approaches of heat transfer control can be developed. | QUO ZengyuanDepartment of Engineering Mechanics, Tsinghua University, Beijing 100084, China | 2001 | Chinese Science Bulletin2001,46,7: | 60 |
| 2 | FLOOD DISCHARGE AND ENERGY DISSIPATION BY JETS FROM OUTLETS IN HIGH ARCH DAM显示文摘In this thesis, the scale effect by an aerated water jet diffusing in the water upon the hydrodynamic pressure, the local riverbed scour by multiple layered jets and by those colliding in the vertical and the transverse directions, and the stability of the apron slab both in the inverted arch cushion pool and the flat bottom one by the large discharge and the high water head with 300m level are detailedly researched by means of model test and numerical simulation. A mathematic model simulating the destabilization of the flat bottomed slab is established to open out the mechanism of its stability. Both experimental researches both on the hydrodynamic pressure acted inside joints between the bedrock and the apron slab, and on forces at arch abutments in inverted arch cushion pool are carried out by using an advanced measurement and the imitation means to acquire the mechanism of the inverted arch pool to keep stability and its stability condition. | Ph.D.Candidate:Sun JianXi’an University of Technolgy, Xi’an 710048, ChinaSupervisor:Yu Changzhao (Tsinghua University, Beijing 100084, China)Li Yuzhu (Tsinghua University, Beijing 100084, China)Chen Changzhi (Tsinghua University, Beijing 100084, China)Members of Dissertation Defense Committee:Gao Jizhang (China Institute of Water Resources and Hydropower Research), ChairmanLi Guifen (China Institute of Water Resources and Hydropower Research)Cui Guangtao (Tianjing University)Wang Xingkui (Tsinghua University)Yu Changzhao (Tsinghua University)Li Yuzhu (Tsinghua University)Chen Changzhi (Tsinghua University) | 2003 | Journal of Hydrodynamics2003,15,1: | 39 |
| 3 | Molecular cloning and functional characterization of a DREB1/CBF-like gene (GhDREB1L) from cotton显示文摘The transcription factors DREB1s/CBFs play important roles in the regulation of plant resistance to environmental stresses and are quite useful for generating transgenic plants tolerant to these stresses. In the present work, a cDNA encoding DREB1/CBF-like protein (GhDREB1L) from cotton was isolated, and its sequence features, DNA binding preference, and expression patterns of the transcripts were also characterized. GhDREB1L contained one conserved AP2/ERF domain and its amino acid sequence was similar to the DREB1/CBF group of the DREB family from other plants. The DNA-binding domain of GhDREB1L was successfully expressed as a fusion protein in Escherichia coli BL21 (DE3) and purified by Ni-NTA affinity chromatography. Electrophoretic mobility shift assay revealed that the purified GhDREB1L fusion protein had a specific binding activity with the previously characterized DRE ele-ment (core sequence, ACCGAC) and also with the DRE-like sequence (core sequence, GCCGAC) in the promoter of the dehydration-responsive late embryogenesis-abundant gene LEA D113. Semi-quantita- tive RT-PCR showed that GhDREB1L was induced in the cotton cotyledons by low temperature, as well as drought and NaCl treatments. These results suggested that the novel cotton GhDREB1L might play an important role in response to low temperature as well as drought and high salinity through binding to the DRE cis-element. | HUANG Bo, JIN LongGuo & LIU JinYuan Laboratory of Molecular Biology and Protein Science Laboratory of the Ministry of Education, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China | 2007 | Science China(Life Sciences)2007,50,1: | 35 |
| 4 | Structure and regulatory function of plant transcription factors显示文摘The expression of inducible genes in plants is regulated by specific transcription factors at the transcrip-tional level. A typical transcription factor usually contains a DNA-binding domain, a transcription regulation domain, a dimerization site and a nuclear localization domain. These functional domains define the characteristic, localization and regulatory role of a transcription factor. Transcription factors recognize and bind to specific cis-acting elements or interact with other proteins, and then activate or repress the transcription of target genes by their functional domains. In recent years, elucidation on the structure and function of transcription factors has become an important subject in plant molecular biology. | LIU Qiang, ZHANG Guiyou & CHEN ShouyiDepartment of Biological Science and Biotechnology, Tsinghua Univorsity, Beijing 100084, China Department of Biological Science and Biotechnology, State Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China Institute of Genetics, Chinese Academy of Sciences, Beijing 100101, China | 2001 | Chinese Science Bulletin2001,46,4: | 36 |
| 5 | Effect of carbon source on the denitrification in constructed wetlands显示文摘The ability of constructed wetlands with different plants in nitrate removal were investigated. The factors promoting the rates of denitrification including organic carbon, nitrate load, plants in wetlands, pH and water temperature in field were systematically investigated. The results showed that the additional carbon source (glucose) can remarkably improve the nitrate removal ability of the constructed wetland. It demonstrated that the nitrate removal rate can increase from 20% to more than 50% in summer and from 10% to 30% in winter, when the nitrate concentration was 30–40 mg/L, the retention time was 24 h and 25 mg/L dissolved organic carbon (DOC) was ploughed into the constructed wetland. However, the nitrite in the constructed wetland accumulated a little with the supply of the additional carbon source in summer and winter, and it increased from 0.15 to 2 mg/L in the effuent. It was also found that the abilities of plant in adjusting pH and temperature can result in an increase of denitrification in wetlands. The seasonal change may also impact the denitrification. | LU Songliu, HU Hongying, SUN Yingxue, YANG Jia ESPC State Key Joint Laboratory, Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China. | 2009 | Journal of Environmental Sciences2009,21,8: | 40 |
| 6 | Classification of hypersurfaces with parallel Mobius second fundamental form in S^(n+1)显示文摘Let Mn(n≥2) be an immersed umbilic-free hypersurface in the(n+1)-dimensional unit sphere Sn+1. Then Mn is associated witha so-called M(o)bius metric g, and a M(o)bius second fundamental form Bwhich are invariants of Mn under the M(o)bius transformation groupof Sn+1.In this paper, we classify all umbilic-free hypersurfaces withparallel M(o)bius second fundamental form. | HU Zejun LI Haizhong Department of Mathematics, Zhengzhou University Zhengzhou 450052, China Department of Mathematical Sciences, Tsinghua University, Beijing 100084, China | 2004 | Science China Mathematics2004,47,3: | 33 |
| 7 | Assessment of candidate plant DNA barcodes using the Rutaceae family显示文摘DNA barcoding is a rapidly developing frontier technology that is gaining worldwide attention.Here,seven regions (psbA-trnH,matK,ycf5,rpoC1,rbcL,ITS2,and ITS) with potential for use as DNA barcodes were tested for their ability to identify 300 samples of 192 species from 72 genera of the family Rutaceae.To evaluate each barcode’s utility for species authentication,PCR amplification efficiency,genetic divergence,and barcoding gaps were assessed.We found that the ITS2 region exhibited the highest inter-specific divergence,and that this was significantly higher than the intra-specific variation in the 'DNA barcoding gap' assessment and Wilcoxon two-sample tests.The ITS2 locus had the highest identification efficiency among all tested regions.In a previous study,we found that ITS2 was able to discriminate a wide range of plant taxa,and here we confirmed that ITS2 was also able to discriminate a number of closely related species.Therefore,we propose that ITS2 is a promising candidate barcode for plant species identification. | LUO Kun1,2,CHEN ShiLin1,CHEN KeLi2,SONG JingYuan1,YAO Hui1,MA XinYe1,ZHU YingJie3,PANG XiaoHui1,YU Hua1,LI XiWen1,4 & LIU Zhen2 1Institute of Medicinal Plant Development,Peking Union Medical College,Chinese Academy of Medical Sciences,Beijing 100193,China 2College of Pharmacy,Hubei University of Chinese Medicine,Wuhan 430061,China 3School of Bioscience and Engineering,Southwest Jiaotong University,Chengdu 610031,China 4Department of Chemistry,Tsinghua University,Beijing 100084,China | 2010 | Science China(Life Sciences)2010,53,6: | 32 |
| 8 | Effects of the Biot and the squirt-flow coupling interaction on anisotropic elastic waves显示文摘Considering the velocity anisotropy of the solid/fluid relative motion and employment of the BISQ theory based on the one-dimensional porous isotropic case, we establish a two-phase anisotropic elastic wave equation to simultaneously include the Biot and the squirt mechanisms in terms of both the basic principles of the fluid’s mass conservation and the elastic-wave dynamical equations in the two-phase anisotropic rock. Numerical results, while the Biot-flow and the squirt-flow effects are simultaneously considered in the transversely isotropic (Tl) poroelastic medium, show that the attenuation of the quasi P-wave and the quasi SV-wave strongly depend on the permeability anisotropy, and the attenuation behavior at low and high frequencies is contrary. Meanwhile, the attenuation and dispersion of the quasi P-wave are also affected seriously by the anisotropic solid/fluid coupling additional density. | YANG Dinghui & ZHANG Zhongjie Department of Mathematical Sciences, Tsinghua University, Beijing 100084, China Institute of Geophysics, Chinese Academy of Sciences, Beijing 100101, China | 2000 | Chinese Science Bulletin2000,45,23: | 33 |
| 9 | Micro-mechanical analysis of dynamic processes of nanomanipulation显示文摘In this study, atomic force microscope (AFM) tips are used as tools to cut and manipulate carbon nanotubes on various surfaces. The lateral forces acting on AFM tips during manipulation are also recorded and analyzed from the perspective of micro-mechanics. It is found that differences in surface conditions can lead to obvious increase in micro-friction between nanotube and substrate. And also due to rehybridization, carbon nanotubes present excellent resilience when undergoing different degrees of strain. Finally, carbon nanotubes can complexly deform from elastic stage to plastic stage before complete rupture. | HU Jie, ZHANG Yujun, LI Peng, WANG Hui, HUANG Lan & HU YuanzhongState Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China Department of Physics, Tsinghua University, Beijing 100084, China College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China | 2004 | Science China(Physics,Mechanics & Astronomy)2004,47,z1: | 28 |
| 10 | Some open problems in granular matter mechanics显示文摘Granular matter is a large assemblage of solid particles, which is fundamentally different from any other type of matters, such as solid and liquid. Most models presented for granular matter are phenomenological and are only suitable for solving engineering problems. Many fundamental mechanical problems remain open. By analyzing characteristics of internal state structure, we propose that granular matter is intrinsically multiscale, i.e. microscale of particle size, mesoscale of force chain, and macroscale of the bulk of granular matter. The correlations among difference scales would be crucial. The mesoscale force chain network is determined by both particle properties and macroscopic boundary conditions. The evolution of the force the chain network contributes to macroscopic mechanical properties of granular matter. In addition, we discuss the drawbacks in simplifying contact forces in the current models, and the difficulties in analyzing the interaction of interstitial fluid in wet granular matter. As an appropriate application of granular matter, debris flow can be studied with granular matter mechanics; meanwhile, debris flow brings more challenges which certainly motivate future studies on granular matter. | Qicheng Sun a, Guangqian Wanga, Kaiheng Hub a Department of Hydraulic Engineering, State Key Laboratory for Hydroscience and Engineering, Tsinghua University, Beijing 100084, China b Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China | 2009 | Progress in Natural Science:Materials International2009,19,5: | 25 |
| 11 | Simulation of dam breach development for emergency treatment of the Tangjiashan Quake Lake in China显示文摘The Tangjiashan Quake Lake is the largest quake lake triggered by the 5.12 Wenchuan Earthquake that happened on May 12,2008 in China,posing high risk of catastrophic flash flood hazards to downstream human life and properties.A physics-based numerical simulation approach is proposed for real-time prediction of dam breach development of the Tangjiashan Quake Lake in the case of emergency treatment.Bed erosion and lateral development of the dam breach are represented through accounting for the underlying physics including selective sediment transport and gravitational collapse.Conceptualized breach erosion model that involves few parameters enables quick calibration based on the monitored hydrological data in emergency analysis where fully geotechnical information about the barrier dam is not available.The process of dam breach development is found to be nonlinear in cascades due to the combined effects of headcutting and bank collapse.The agreement between the simulation results and the observed data shows the applicability of the present approach for emergency analysis of quake lakes.Limitations will arise in the situation where the soil composition of barrier dam is significantly inhomogeneous.Incorporation of circular arc failure for cohesive soil and lateral seepage in bank slope will also enhance its applicability to complex situations. | WANG GuangQian,LIU Fan,FU XuDong & LI TieJian State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China | 2008 | Science China(Technological Sciences)2008,51,S2: | 25 |
| 12 | Investigation of heavy metal partitioning influenced by flue gas moisture and chlorine content during waste incineration显示文摘The impact of moisture on the partitioning of the heavy metals including Pb,Zn,Cu and Cd in municipal solid waste (MSW) was studied in a laboratory tubular furnace.A thermodynamic investigation using CHEMKIN software was performed to compare the experimental results.Simulated waste,representative of typical MSW with and without chlorine compounds,was burned at the background temperature of 700 and 950°C,respectively.In the absence of chlorine,the moisture content has no evident effect on the volatility of Pb,Zn and Cu at either 700 or 950°C,however,as flue gas moisture increasing the Cd distribution in the bottom ash increased at 700°C and reduced at 950°C,respectively.In the presence of chlorine,the flue gas moisture reduced the volatility of Pb,Zn and Cu due to the transformation of the more volatile metal chlorides into less volatile metal oxides,and the reduction became significant as chlorine content increase.For Cd,the chlorine promotes its volatility through the formation of more volatile CdCl 2.As a result,the increased moisture content increases the Pb,Zn,Cu and Cd concentrations in the bottom ash,which limits the utilization of the bottom ash as a construction material.Therefore,in order to accumulate heavy metals into the fly ash,MSW should be dried before incineration. | Qinghai Li,Aihong Meng,Jinyan Jia,Yanguo Zhang Department of Thermal Engineering,Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education of China,Tsinghua University,Beijing 100084,China. | 2010 | Journal of Environmental Sciences2010,22,5: | 24 |
| 13 | Numerical simulation of air-water two-phase flow over stepped spillways显示文摘Stepped spillways for significant energy dissipation along the chute have gained interest and popularity among researchers and dam engineers. Due to the com- plexity of air-water two-phase flow over stepped spillways, the finite volume computational fluid dynamics module of the FLUENT software was used to simulate the main characteristics of the flow. Adopting the RNG k-ε turbulence model, the mixture flow model for air-water two-phase flow was used to simulate the flow field over stepped spillway with the PISO arithmetic technique. The numerical result successfully reproduced the complex flow over a stepped spillway of an experiment case, including the interaction between entrained air bubbles and cavity recirculation in the skimming flow regime, velocity distribution and the pressure profiles on the step surface as well. The result is helpful for under-standing the detailed information about energy dissipation over stepped spillways. | CHENG Xiangju1, CHEN Yongcan1 & LUO Lin2 1. Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China 2. State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China | 2006 | Science China(Technological Sciences)2006,49,6: | 23 |
| 14 | Change of surface cover greenness in China between 2000 and 2010显示文摘Surface greenness reflects the situation of vegetation cover.Vegetation index calculated from the Red and Near Infrared bands of remote sensing images,whose values indicate the level of photosynthetic activity,is monotonically related to surface greenness when vegetation canopy does not fully cover the background soil.Especially for desert regions,vegetation index is positively correlated with vegetation coverage.Therefore,vegetation index can be used to study the change in greenness of desert areas.This study collected MODIS Normalized Difference Vegetation Index (NDVI) data from 2000 to 2010 and analyzed their change over China in this period.The results showed that an increasing trend of NDVI occurred over 66.84% (OLS fitting) or 64.27% (LAD fitting) of China,indicating that China's greenness is increasing overall.Meanwhile,desertification of China decreased.Areas showing large increase in greenness are found in Shaanxi,Shanxi,Ningxia,Henan,Shandong,Qinghai,and Gansu while regions with large decrease in greenness are found in Northeast Inner Mongolia,South Tibet,Jiangsu,and Shanghai.Changes of Qinghai,Gansu,Xinjiang and South Tibet could probably be driven by climate factors.Decrease of greenness in Northeast Inner Mongolia was related to agricultural reclamation.Decrease of greenness in Jiangsu and Shanghai was related to rapid urbanization.Climate factors did not exhibit obvious correspondence to the large increase in greenness in Shaanxi,Shanxi,Ningxia and Gansu,indicating that the changes might have been caused by human factors.The reduction of desert areas in China could probably have been caused by human management and protection at the national scale. | LIU Shuang1,4& GONG Peng1,2,31State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Institute of Remote Sensing Applications of Chinese Academy of Sciences,and Beijing Normal University, Beijing 100101, China 2Institute for Global Change Studies & Center for Earth System Science, Tsinghua University, Beijing 100084, China 3Department of Environmental Science, Policy and Management, University of California, Berkeley, CA94720, USA 4Graduate University of Chinese Academy of Sciences, Beijing 100049, China | 2012 | Chinese Science Bulletin2012,57,22: | 23 |
| 15 | Deformation reinforcement theory and its application to high arch dams显示文摘In this paper,the deformation reinforcement theory(DRT) proposed by the authors is elaborated with a new definition of instability that an elasto-plastic structure is not stable if it cannot satisfy simultaneously equilibrium condition,kinematical admissibility and constitutive equations under the prescribed loading.Starting from the definition,a proof is established to the principle of minimum plastic complementary energy for failured structures.It is revealed that the principle of mini-mum plastic complementary energy results in relaxed constitutive equations,especially,yield conditions.It is demonstrated with case studies that many key issues in arch dam design,e.g.,global stability,dam-toe reinforcement,dam-toe cracking,dam-abut-ment reinforcement,can be well solved within the framework of the deformation reinforcement theory.The structural global stability can be described by the curve of the plastic complementary energy vs overloading factor.The unbalanced-forces obtained by elasto-plastic FEM can be used as the basis of analysis of global stability,dam-heel cracking,dam-toe anchorage and reinforcement of faults of high arch dams and their foundations. | YANG Qiang,LIU YaoRu,CHEN YingRu & ZHOU WeiYuan State Key Laboratory of Hydroscience and Hydraulic Engineering,Tsinghua University,Beijing 100084,China | 2008 | Science China(Technological Sciences)2008,51,S2: | 21 |
| 16 | Eavesdropping in a quantum secret sharing protocol based on Grover algorithm and its solution显示文摘A detailed analysis has showed that the quantum secret sharing protocol based on the Grover algorithm (Phys Rev A, 2003, 68: 022306) is insecure. A dishonest receiver may obtain the full information without being detected. A quantum secret-sharing protocol is presents here, which mends the security loophole of the original secret-sharing protocol, and doubles the information capacity. | HAO Liang1, LI JunLin1 & LONG GuiLu1,2 1Key Laboratory for Atomic and Molecular NanoSciences and Department of Physics, Tsinghua University, Beijing 100084, China 2Tsinghua National Laboratory for Information Science and Technology, Beijing 100084, China | 2010 | Science China(Physics,Mechanics & Astronomy)2010,53,3: | 20 |
| 17 | Moran sets and Moran classes显示文摘The purpose of this survey is to present Moran sets and Moran classes which generalize the classical self-similar sets from the following points: (i) The placements of the basic sets at each step of the constructions can be arbitrary; (ii) the contraction ratios may be different at each step; and (iii) the lower limit of the contraction ratios permits zero. In this discussion we will present geometrical properties and results of dimensions of these sets and classes, and discuss conformal Moran sets and random Moran sets as well. | WEN ZhiyingDepartment of Mathematics, Tsinghua University, Beijing 100084, China | 2001 | Chinese Science Bulletin2001,46,22: | 20 |
| 18 | Arbitrarily long distance quantum communication using inspection and power insertion显示文摘The biggest obstacle for long distance quantum communication is the channel loss and the channel noise on photons. In this paper,a method to solve this problem was analyzed using inspection and power insertion (IPI). It is proved that quantum communication may be established over arbitrarily long distance using this technology. The amount of resources required is a polynomial function of the dis-tance. IPI is proposed as a general technique to prolong quantum secure direct communication where secret messages are transmitted directly over a quantum channel. | WANG WanYing1,2,WANG Chuan1,2,ZHANG GuangYu1,3 & LONG GuiLu1,2 1 Department of Physics,Tsinghua University,Beijing 100084,China 2 Tsinghua National Laboratory for Information Science and Technology,Tsinghua University,Beijing 100084,China 3 College of Applied Science,Harbin University of Science and Technology,Harbin 150080,China | 2009 | Chinese Science Bulletin2009,54,1: | 19 |
| 19 | Effect of L-NAME on nitric oxide and gastrointestinal motility alterations in cirrhotic rats显示文摘AIM: To invsstigare the effect of L-NAME on nitric oxide andgastriubtestubal motility alterations in cirrhotic ratsMETHODS: Rats with cirrhosis induced by carbontetrachloride were randomly divided into two groups, one( n= 13) receiving 0. 5 mg@ kg-1 per clay of NG-nitro-L-argininemethyl ester (L-NAME), a nitric oxide synthase inhibitor,for 10 days, whereas the other group ( n = 13) and control( n = 10) rats were administrated the same volume of 9 g@ L-1saline.Half gastric emptying time and 2 h residual rate weremeasured by SPECT, using 99m Tc-DTPA-labeled bariumsuifate as test meal. Gastrointestinal transition time wasrecorded simultaneously. Serum concentration of nitrcoxide (NO) was determined by the kinetic cadmiunreduction and colorimetric methods. ImmunohistochemicalSABC method was used to observe the expression anddistribution of three types of nitric oxide synthase (NOS)isoforms in the mt gastrointestinal tract. Western blot wasused to detect expression of gastrointestinal NOS isoforms.RESULTS: Half gastric emptying time and trans-gastrointestinal time were significantly prolonged( 124.0 ± 26.4min; 33.7± 8.9min;72.1 ± 15.3 min; P<0.01), (12.4±0.5h; 9.5±0.3 h; 8.2±0.8 h; P<0.01), 2h residual rate wasraised in cirrhotic rots than in controls and cirrhotic ratstreated with L-NAME(54.9± 7.6 % ,13.7 ± 3.2 %, 34.9± 10.3%, P< 0.01). Serum concentration of NO was significantlyincreased in cirrhotic rots than in the other groups (8.20 ± 2.48)μmol@L-1, (5.94± 1.07) μmol@L-1 ,and control (5.66± 1.60) tμmol@L-1, P< 0.01. NOS staining intensities which weremainly located in the gastrointestinal tissues were markedlylower in cirrhotic rats than in the controls and cirrhotic ratsafter treated with L- NAME.CONCLUSION: Gastrointestinal motility was remarkablyinhibited in cirrhotic rats, which could he alleviated by L-NAME. Nitric oxide may play an important role in theinhibition of gastrointestinal motility in cirrhotic rats. | Xin Wang Zong-You Zhang Mei Lan Ji-Yan Miao Xue-Gang Guo Yong-Quan Shi Yan-Qiu Zhao Jie Ding Kai-Cun Wu Dai-Ming Fan,Institute of Digestive disease,Xijing Hospital,Fourth Military Medical University,Xi’an 710032,Shaanxi Province,China Yue-Xia Zhong,Emergency Department,Tangdu Hospital,Fourth Military Medical University,Xi’an 710038,Shaanxi Province,China Ju Lu,Class EE 87,Department of Electronic Engineering,Tsinghua University,Beijing 100084,China Bo-Rong Pan,Oncology Center,Xijing Hospital,Fourth Military Medical University,Xi’an 710032,Shaanxi Province,China | 2002 | World Journal of Gastroenterology2002,8,2: | 19 |
| 20 | Dense coding scheme using superpositions of Bell-states and its NMR implementation显示文摘Dense coding using superpositions of Bell-states is proposed. The generalized Grover's algorithm is used to prepare the initial entangled states, and the reverse process of the quantum algorithm is used to determine the entangled state in the decoding measurement. Compared with the previous schemes, the superpositions of two Bell-states are exploited. Our scheme is demonstrated using a nuclear magnetic resonance (NMR)quantum computer. The corresponding manipulations are obtained. Experimental results show a good agreement between theory and experiment. We also generalize the scheme to transmit eight messages by introducing an additional two-state system. | ZHANG Jingfu, XIE Jingyi, DENG Zhiwei & LU Zhiheng Key Laboratory for Quantum Information and Measurements, Department of Physics, Tsinghua University, Beijing 100084, China Center for Quantum Information, Tsinghua University, Beijing 100084, China Department of Materials Science and Engineering, Beijing Normal University, Beijing 100875, China Testing and Analytical Center, Beijing Normal University, Beijing 100875, China Department of Physics, Beijing Normal University, Beijing 100875, China | 2005 | Science China(Physics,Mechanics & Astronomy)2005,48,1: | 18 |