检索结果-南通市图书馆

Inconsistency between WMAP data and released map

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2010年第10期55卷 907-909页

作者： LIU Hao1 & LI TiPei1,2,3 1 Key Laboratory of Particle astrophysics,Institute of High Energy physics,Chinese Academy of Sciences,beijing 100049,china 2 department of physics & center for astrophysics,tsinghua university,beijing 100084,china 3.department of engineering physics & center for astrophysics,tsinghua university,beijing 100084,china Key Laboratory of Particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China department of physics & center for astrophysics Tsinghua University Beijing China department of engineering physics & center for astrophysics Tsinghua University Beijing China

A remarkable inconsistency between the calibrated differential time-ordered data (TOD) of the Wilkinson Microwave Anisotropy Probe (WMAP) mission,which is the input for map-making,and the cosmic microwave background (CMB) temperature maps published by the WMAP team is revealed,indicating that there must exist a serious problem in the map making routine of the WMAP *** inconsistency is easy to be confirmed without the use of WMAP map-making *** view of the importance of this issue for cosmology study,we invite readers to check it by themselves.

关键词：威尔金森微波各向异性探测器 WMAP 地图制作宇宙微波背景有序数据制作软件 TOD CMB

Constraints on Cardassian universe from Gamma ray bursts

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2010年第9期53卷 1720-1725页

作者： WANG TaiShan1 & LIANG Nan2 1 department of physics & center for astrophysics,tsinghua university,beijing 100084,china 2 department of Astronomy,beijing Normal university,beijing 100875,china 1. department of physics & center for astrophysics Tsinghua University Beijing 100084 China2. Department of Astronomy Beijing Normal University Beijing 100875 China

Constraints on the original Cardassian model and the modified polytropic Cardassian model are examined from the recently derived 42 gamma-ray bursts(GRBs) data calibrated with the method that can avoid the circularity *** results show that GRBs can be an optional observation to constrain the Cardassian *** the GRBs data with the newly de-rived size of baryonic acoustic oscillation peak from the Sloan Digital Sky Survey(SDSS),and the position of the first acoustic peak of the Cosmic Microwave Background radiation(CMB) from Wilkinson Microwave Anisotropy Probe(WMAP),we find Ωm0=0.27+0.02-0.02,n=0.06+0.07-0.08(1σ) for the original Cardassian model,and Ωm0=0.27+0.23-0.02,n=-0.09+0.23-1.91,β=0.82+2.10-0.62(1σ) for the modified polytropic Cardassian model.

关键词： Cardassian Gamma ray burst Cosmic Microwave Background baryonic acoustic oscillation

Timing in the Time Domain: Cygnus X-1

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Astronomy and astrophysics 2001年第4期1卷 313-332页

作者： Ti-Pei Li (department of physics and center for astrophysics, tsinghua university, beijing 100084 High Energy astrophysics Lab., Institute of High Energy physics, Chinese Academy of Sciences, beijing 100039)E-mail:litp@*** department of physics and center for astrophysics Tsinghua University Beijing 100084 High Energy Astrophysics Lab. Institute of High Energy Physics Chinese Academy of Sciences Beijing 100039

Quantities characterizing temporal property, e.g., power density, coherence, and time lag, can be defined and calculated directly in the time domain without using the Fourier transformation. Spectral hardness, variability duration, and correlation between different characteristic quamtities on different time scale can be studied in the time domain as well. The temporal analysis technique in the time domain is a powerful tool, particularly in studying rapid variability on short time scales (or in high frequencies). Results of studying variabilities of X-rays from Cyg X-1 with the analysis technique in the time domain and RXTE data reveal valuable clues to understanding production and propagation processes of X-rays and structure of accretion disk in the black hole system.

关键词： methods: data analysis - stars: individual (Cygnus X-1) - X-rays: stars

Dense coding scheme using superpositions of Bell-states and its NMR implementation

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2005年第1期48卷 57-67页

作者： 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 1. Key Laboratory for Quantum Information and Measurements Department of Physics Tsinghua University 100084 Beijing China 2. center for Quantum Information Tsinghua University 100084 Beijing China 3. department of Materials Science and engineering Beijing Normal University 100875 Beijing China 4. Testing and Analytical center Beijing Normal University 100875 Beijing China 5. department of physics Beijing Normal University 100875 Beijing China

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.

关键词： dense coding, superpositions of Bell-states, generalized Grover's algorithm, nuclear magnetic res-onance, quantum computer.

Evaluation of Surface Cracks Using Magnetic Flux LeakageTesting

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2002年第4期18卷 319-321页

作者： Luming LI, Songling HUANG, Peng ZHENG and Keren SHINUT center, Mechanical engineering department, tsinghua university, beijing 100084, china NDT Cent. Mech. Eng. Dept. Tsinghua Univ. Beijing 100084 China

The magnetic field distribution characteristics of surface cracks with various widths are discussed based on finite element (FEM) results. The crack depth was 0.20 mm, the width range was from 0.02 to 1.00 mm. The results showed that crack width and lift-off (the distance between surface and sensor) will influence signals. Discussed in this paper is the influence of various lift-off parameters on the peak to peak values of the normal component in magnetic flux leakage testing. The effects can be applied to evaluate surface breaking cracks of different widths and depths. An idea is presented to smooth narrow, sharp crack tips using alternating current (AC) field magnetization.

关键词： Magnetic flux leakage testing (MFL) Slot width Finite element method (FKM)

Anomalous magnetotransport in LaMn_(1-x)Te_xO_3

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2009年第7期52卷 987-992页

作者： TAN GuoTai1,2, CHEN ZhengHao3 & ZHANG XiaoZhong4,5 1 Key Laboratory of Beam Technology & Materials Modification of the Ministry of Education, Institute of Low Energy Nuclear physics, beijing Normal university, beijing 100875, china 2 beijing Radiation center, beijing 100875, china 3 Laboratory of Optical physics, Institute of physics, Chinese Academy of Sciences, beijing 100080, china 4 Key Laboratory of Advanced Materials of the Ministry of Education, department of Materials Science and engineering, tsinghua university, beijing 100084, china 5 beijing National center for Electron Microscopy, tsinghua university, beijing 100084, china 1. Key Laboratory of Beam Technology & Materials Modification of the Ministry of Education Institute of Low Energy Nuclear Physics Beijing Normal University Beijing 100875 China 2. beijing Radiation center Beijing 100875 China 3. Laboratory of Optical physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China 4. Key Laboratory of Advanced Materials of the Ministry of Education Department of Materials Science and Engineering Tsinghua University Beijing 100084 China 5. beijing National center for Electron Microscopy Tsinghua University Beijing 100084 China

The LaMn1-xTexO3+δ (x=0.1, 0.2, 0.3) were synthesized using solid-state reaction method for the first time. X-ray photoemission spectrum (XPS) shows that in the samples the Te ions have a valence of Te4+, and Mn3+ ions are partly converted into Mn2+ and Mn4+ due to the excess oxygen and Te doping. The magnetotransport associated with Mn2+, Mn3+ and Mn4+ was investigated. The experimental results show that the samples are insulator at 0 T when the amount of Mn3+ is much larger or less than the sum of Mn2+ and Mn4+; by contrast, the samples display metal to insulator transition with increasing temperature when the amount of Mn3+ is close to the sum of Mn2+ and Mn4+. These anomalous magnetotransport behaviors were analyzed in the frame of the double-exchange (DE) mechanism.

关键词： colossal magnetoresistance La-Te-Mn-O magnetotransport

Two-fluid Dynamics in Clusters of Galaxies

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Astronomy and astrophysics 2005年第1期5卷 6-20页

作者： Yu-Qing LouNational Astronomical Observatories, Chinese Academy of Sciences, beijing 100012department of physics & tsinghua center for astrophysics (THCA), tsinghua university, beijing 100084 department of Astronomy and astrophysics, The university of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 USA National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

We develop a theoretical formulation for the large-scale dynamics of galaxy clusters involving two spherical 'isothermal fluids' coupled by their mutual gravity and derive asymptotic similarity solutions analytically. One of the fluids roughly approximates the massive dark matter halo, while the other describes the hot gas, the relatively small mass contribution from the galaxies being subsumed in the gas. By properly choosing the self-similar variables, it is possible to consistently transform the set of time-dependent two-fluid equations of spherical symmetry with self-gravity into a set of coupled nonlinear ordinary differential equations (ODEs). We focus on the analytical analysis and discuss applications of the solutions to galaxy clusters.

关键词： dark matter - hydrodynamics - ISM: general - galaxies: clusters -outflows winds - shocks

Development of a model to generate a risk map in a building fire

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第10期53卷 2739-2747页

作者： CHU YanYan, ZHANG Hui, SHEN ShiFei, YANG Rui & QIAO LiFeng center for Public Safety Research, department of engineering physics, tsinghua university, beijing 100084, china 1. center for Public Safety Research Department of Engineering Physics Tsinghua University Beijing 100084 China

Fire simulations and sensors are widely used in building fires,various data such as temperature,CO and CO2 concentration,visibility can be obtained by sensors and sensor-based simulation. It is important to generate a risk map based on such data so that we can use it to estimate safety of the building. In this paper,we propose a method to generate a dynamical,integrated risk map using sensor readings in a building fire. Such risk evaluation model is developed using similarity comparison between the space state and dangerous state by a likelihood distance calculating and data grouping from a two-step cluster method. The risk evaluation model considers the integrated influence on the occupants in the zone from high temperature,lack of oxygen,toxic and harmful gases and shows the relative fire risk map at certain time. Based on the simulation study,it is proved that multi-factor fire risk analysis would be more objective and accurate than single factor and two-factor risk analysis and the fire risk evaluation model can generate a risk map and provide the classification information and the whole building risk statistic results to support evacuation command and control.

关键词： building fire risk map cluster analysis fire simulation

Multiparty quantum secret sharing of classical and quantum messages

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第1期17卷 26-31页

作者： CHEN Pan, DENG Fuguo and LONG Guilu ( Key Laboratory for Quantum Information and Measurements, and department of physics, tsinghua university, beijing 100084, china Key Laboratory of Beam Technology and Material Modification, MOE, Institute of Low Energy Nuclear physics, and department of Material Science and engineering, beijing Normal university, beijing 100875, china beijing Radiation center, beijing 100875, china Key Laboratory for Atomic and Molecular Nano-Sciences, tsinghua university, beijing 100084, china) [a]Key Laboratory for Quantum Information and Measurements and Department of Physics Tsinghua University Beijing China [b]Key Laboratory of Beam Technology and Material Modification MOE Institute of Low Energy Nuclear Physics and Department of Material Science and Engineering Beijing Normal University Beijing China [c]beijing Radiation center Beijing China [d]Key Laboratory for Atomic and Molecular Nano-Sciences Tsinghua University Beijing China

A scheme for multiparty quantum secret sharing of classical and quantum messages is proposed by using entanglement swapping. This scheme can distribute not only the classical information but also the quantum informati... 详细信息

关键词： quantum secret sharing classical message quantum message EPR pair.