检索结果-南通市图书馆

An overview of computational photography

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

Science china(Information Sciences) 2012年第6期55卷 1229-1248页

作者： SUO JinLi,JI XiangYang & DAI QiongHai Department of Automation,tsinghua university,beijing 100084,china 1. Department of Automation Tsinghua University Beijing 100084 China

Computational photography is an emerging multidisciplinary *** the last two decades,it has integrated studies across computer vision,computer graphics,signal processing,applied optics and related *** are exploring new ways to break through the limitations of traditional digital imaging for the benefit of photographers,vision and graphics researchers,and image processing *** to much effort in various associated fields,the large variety of issues related to these new methods of photography are described and discussed extensively in this *** give the reader the full picture of the voluminous literature related to computational photography,this paper briefly reviews the wide range of topics in this new field,covering a number of different aspects,including:(i) the various elements of computational imaging systems and new sampling and reconstruction mechanisms;(ii) the different image properties which benefit from computational photography,*** of field,dynamic range;and(iii) the sampling subspaces of visual scenes in the real *** on this systematic review of the previous and ongoing work in this field,we also discuss some open issues and potential new directions in computational *** paper aims to help the reader get to know this new field,including its history,ultimate goals,hot topics,research methodologies,and future directions,and thus build a foundation for further research and related developments.

关键词： computational photography computational imaging plenoptic function light field

Experimental realization of quantum cryptography communication in free space

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2005年第2期48卷 237-246页

作者： WANG Chuan1, ZHANG Jingfu1, WANG Pingxiao1, DENG Fuguo1, AI Qing1 & LONG Guilu1,2 1. Department of Physics, Key Laboratory for Quantum Information and Measurements, tsinghua Univer- sity, beijing 100084, china 2. center for Atomic and Molecular NanoSciences, tsinghua university, beijing 100084, china Department of Physics Key Laboratory for Quantum Information and Measurements Tsinghua University Beijing 100084 China Atomic and Molecular NanoSciences Tsinghua University Beijing 100084 China

Utilizing linear optical devices, the principle of B92 quantum key distribution (QKD) protocol is demonstrated in free space with a distance of transmission of 2.2 meters. The faint laser pulses with 650 nm wavelength are used as the single photon sources. The experimental results show that the eavesdropping behavior in the signal transmission can be detected. We also discuss the problems and solutions in using the quantum cryptography communication practically. It is pointed out that one of the approaches to increasing the distance of the quantum communication is to overcome the attenuation of the single photon in transmission. This could not be solved by the use of single photon source, and new quantum communication protocols are needed to solve these problems.

关键词： quantum key distribution, free space, linear optics, faint pulses.

research on Electric Impedance Spectroscopy of Living Cell Suspensions by a Chip with Microelectrodes

在线全文

学校读者我要写书评

暂无评论

稀有金属材料与工程 2006年第S3期 429-432页

作者： Xing Yang~(1,2,3) Zhaoying Zhou~(1,2,3) Mingfei Xiao~(1,2,3) Ying Wu~(1,2,3) Shangfeng Liu~4 (1.MEMS Lab.,Department of Precision Instruments & Mechanology,tsinghua university,beijing 100084,china) (2.Micro-Nano Technology research center,tsinghua university,beijing 100084,china) (3.State Key Laboratory of Precision Measurement Technology and Instruments,tsinghua university,beijing 100084,china) (4.School of Medicine,tsinghua university,beijing 100084,china)

A microfabricated electrical impedance spectroscopy (EIS) chip with microelectrodes was *** substrate and the electrodes of the chip were made of glass and gold,*** experimental results demonstrated that the EIS-chip could distinguish different solutions (physiological saline,culture medium,living cell suspension etc.) by scanning from 10Hz to 45kHz.A 6-element circuit model was used for fitting the real part and the imaginary part admittance curves of the living cell *** actual circuit was also built and tested to verify the 6-element circuit model *** micro-EIS chip has several advantages including the use of small sample volumes,high resolution and ease of *** shows good application prospects in the areas of cellular electrophysioiogy,drug screening and bio-sensors etc.

关键词： electrical impedance spectroscopy(EIS) microelectrode living cell suspension 6-element

Performance Modeling and Approximate Analysis of Multiserver Multiqueue Systems with Poisson and Self-similar Arrivals

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 university of Science and Technology beijing 2001年第2期8卷 145-151页

作者： Zhiguang Shan, Chuang Lin, Yang Yang, Yan Wang (Information Engineering School, university of Science and Technology beijing, beijing 100083, china) (Department of Computer Science and Technology, tsinghua university, beijing 100084, china) Univ Sci & Technol beijing Informat Engn Sch Beijing 100083 Peoples R China tsinghua Univ Dept Comp Sci & Technol Beijing 100084 Peoples R China

The problem of state space explosion is still ran outstanding challenge in Markovian performance analysis for multiserver multiqueue (MSMQ) systems. The system behavior of a MSMQ system is described using stochastic high-level Petri net (SHLPN) models, and an approximate performance analysis technique is proposed based on decomposition and refinement methods as well as iteration technique. A real MSMQ system, Web-server cluster, is investigated. The performance of an integrated scheme of request dispatching and scheduling is analyzed with both Poisson and self-similar request arrivals. The study shows that the approximate analysis technique significantly reduces the complexity of the model solution and is also efficient for accuracy of numerical results.

关键词： multiserver multiqueue (MSMQ) system Web-server cluster performance analysis stochastic high-level Petri net (SHLPN) request dispatching request scheduling

Two mode photon bunching effect as witness of quantum criticality in circuit QED

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12期52卷 1898-1905页

作者： AI Qing1,WANG YingDan2,LONG GuiLu1,3 & SUN ChangPu4 1 Department of Physics,tsinghua university,beijing 100084,china 2 Department of Physics,university of Basel,Klingelbergstrasse 82,4056 Basel,Switzerland 3 tsinghua National Laboratory for Information Science and Technology,beijing 100084,china 4 Institute of Theoretical Physics,Chinese Academy of Sciences,beijing 100080,china 1. Department of Physics Tsinghua University Beijing 100084 China 2. Department of Physics University of Basel Klingelbergstrasse 82 4056 Basel Switzerland 3. tsinghua National Laboratory for Information Science and Technology Beijing 100084 China 4. Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100080 China

We suggest a scheme to probe critical phenomena at a quantum phase transition (QPT) using the quantum correlation of two photonic modes simultaneously coupled to a critical system. As an experimentally accessible physical implementation,a circuit QED system is formed by a capacitively coupled Josephson junction qubit array interacting with one superconducting transmission line resonator (TLR). It realizes an Ising chain in the transverse field (ICTF) which interacts with the two magnetic modes propagating in the TLR. We demonstrate that in the vicinity of criticality the originally independent fields tend to display photon bunching effects due to their interaction with the ICTF. Thus,the occurrence of the QPT is reflected by the quantum characteristics of the photonic fields.

关键词： quantum phase transition photon bunching circuit QED

Comparison of fractal measures

在线全文

学校读者我要写书评

暂无评论

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 university,beijing 100084,china Department of Mathematics,Hubei university, 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 3Pd 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 03Ps|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.

Dynamics and control of a solar collector system for near Earth object deflection

在线全文

学校读者我要写书评

暂无评论

research in Astronomy and Astrophysics 2011年第2期11卷 205-224页

作者： Shen-Ping Gong,Jun-Feng Li and Yun-Feng Gao School of Aerospace,tsinghua university,beijing 100084,china School of Aerospace Tsinghua University Beijing 100084 China

A solar collector system is a possible method using solar energy to deflect Earth-threatening near-Earth *** investigate the dynamics and control of a solar collector system including a main collector （MC） and secondary collector （SC）.The MC is used to collect the sunlight to its focal point,where the SC is placed and directs the collected light to an *** the relative position and attitude of the two collectors should be accurately controlled to achieve the desired optical ***,the dynamical equation of the relative motion of the two collectors in the vicinity of the asteroid is ***,the nonlinear sliding-mode method is employed to design a control law to achieve the desired configuration of the two ***,the deflection capability of this solar collector system is compared with those of the gravitational tractor and solar sail gravitational *** results show that the solar collector is much more efficient with respect to deflection capability.

关键词： minor planets asteroids -- techniques: miscellaneous -- solar collector

Physical analysis and numerical simulation for the dynamic behaviour of vehicles in pitching oscillations or rocking motions

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2007年第4期50卷 385-401页

作者： ZHANG HanXin1,2,3, ZHANG Zhao1,3, YUAN XianXu1,2, LIU Wei1, XIE YuFei1,2 & YE YouDa1,2 1 china Aerodynamics research and Development center, Mianyang 621000, china 2 National Laboratory for Computational Fluid Dynamics, beijing university of Aeronautics and Astronautics, beijing 100083, china 3 School of Aerospace, tsinghua university, beijing 100084, china 1. china Aerodynamics research and Development center Mianyan 621000 China 2. National Laboratory for Computational Fluid Dynamics Beijing University of Aeronautics and Astronautics Beijing 100083 China 3. School of Aerospace Tsinghua University Beijing 100084 China

Analytical methods of nonlinear dynamics and numerical simulations for the cou-pling equations of Navier-Stokes and flight mechanics are used to study the dynamic behaviour of pitching motions of reentry capsules with the variation of Mach number, and rocking motions of swept wings with the variation of angle of attack. Conditions under which the dynamic instability, Hopf bifurcation and saddle-node bifurcation occur are obtained. The node-saddle-node topological structure in the phase portrait, i.e. the state of bi-attractors (attracting basins) is described. The evolving process of dynamic behaviour and flow fields are given. The theories are compared with some numerical simulations conducted by the authors. Besides, some verifiable experi-mental results are cited. The agreement between them is very well.

关键词： physical analysis numerical simulation pitching oscillation rocking motion bifurcation

Sediment pollution and its effect on fish through food chain in the Yangtze River

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment research 2008年第4期23卷 338-347页

Suspended sediment adsorbs pollutants from flowing water in rivers and deposits onto the bed. However, the pollutants accumulated in the river bed sediment may affect the bio-community through food chain for a long period of time. To study the problem the concentration of heavy metals (Cr, Cd, Hg, Cu, Fe, Zn, Pb and As) in water, sediment, and fish/invertebrate were investigated in the middle and lower reaches of the Yangtze River during 2006-2007. The concentrations of heavy metals were 100-10,000 times higher in the sediment than in the water. Benthic invertebrates had relatively high concentrations of heavy metals in their tissues due to their proximity to contaminated sediments. Benthic invertivore fish had moderately high concentrations of heavy metals whereas phytoplanktivore fish, such as the silver carp, accumulated the lowest concentration of heavy metals. The concentrations of Cu, Zn, and Fe were higher than Hg, Pb, Cd, Cr, and As in the tissue samples. The concentration of heavy metals was lower in the river sediments than in the lake sediments. Conversely, the concentration of heavy metals was higher in river water than in lake water. While a pollution event into a water body is often transitory, the effects of the pollutants may be long-lived due to their tendency to be absorbed in the sediments and then released into the food chain. The heavy metals were concentrated in the following order: bottom material > demersal fish and benthic fauna > middle-lower layer fish > upper-middle layer fish > water.

关键词： Sediment pollution Heavy metal Fish Invertebrate Yangtze River