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Experimental simulation of violation of the Wright inequality by coherent light

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Chinese Physics B 2017年第10期26卷 49-53页

作者：朱锋张巍黄翊东 tsinghua National Laboratory for Information Science and Technology Department of Electronic Engineering Tsinghua University

In this paper, we investigate the simulation of violation of the Wright inequality by the classical optical experiment theoretically and experimentally. The feasibility of the simulation is demonstrated by theoretical analysis based on descriptions of the classical electrodynamics and quantum mechanics, respectively. Then, the simulation of violation of the Wright inequality is realized experimentally. The setup is based on a laser source, free-space optical devices and power meters. The experimental result violates the noncontextuality hidden variable bound, agreeing with the quantum bound. This method can be extended to other types of noncontextuality inequalities.

关键词： quantum optics polarization quantum information and processing

Maximal Regularity of Second Order Delay Equations in Banach Spaces

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Acta Mathematica Sinica,English Series 2009年第1期25卷 21-28页

作者： Shang Quan BU Department of Mathematical Science Tsinghua University Beijing 100084 P. R. China

Using known Ca-multiplier result, we give necessary and sufficient conditions for the second order delay equations：u″（t）=Au（t）＋Fut＋Gu′＋f（t）,t∈Rto have maximal regularity in HSlder continuous function spaces C^α （R, X）, where X is a Banach space, A is a closed operator in X, F, G ∈L（C（[-r, 0], X）, X） are delay operators for some fixed r 〉 0.

关键词： maximal regularity delay equations Hoelder continuous functions C^α-multiplier

Dielectric barrier discharge-based defect engineering method to assist flash sintering

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Journal of Advanced Ceramics 2023年第5期12卷 1046-1057页

作者： Xinhao Zhao Nianping Yan Yueji Li Zikui Shen Rongxia Huang Chen Xu Xuetong Zhao Xilin Wang Ruobing Zhang Zhidong Jia Guangdong Engineering Technology research Center of Power Equipment Reliability in Complicated Coastal Environments Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China State Grid Jiangxi Electric Power research Institute Nanchang 330096China School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China Institute of Materials China Academy of Engineering PhysicsMianyang 621907China fSchool of Electrical Engineering Chongqing UniversityChongqing 400044China

Oxygen vacancy OV plays an important role in a flash sintering (FS) process. In defect engineering, the methods of creating oxygen vacancy defects include doping, heating, and etching, and all of them often have complex processes or equipment. In this study, we used dielectric barrier discharge (DBD) as a new defect engineering technology to increase oxygen vacancy concentrations of green billets with different ceramics (ZnO, TiO_(2), and 3 mol% yttria-stabilized zirconia (3YSZ)). With an alternating current (AC) power supply of 10 kHz, low-temperature plasma was generated, and a specimen could be treated in different atmospheres. The effect of the DBD treatment was influenced by atmosphere, treatment time, and voltage amplitude of the power supply. After the DBD treatment, the oxygen vacancy defect concentration in ZnO samples increased significantly, and a resistance test showed that conductivity of the samples increased by 2–3 orders of magnitude. Moreover, the onset electric field (E) of ZnO FS decreased from 5.17 to 0.86 kV/cm at room temperature (RT);while in the whole FS, the max power dissipation decreased from 563.17 to 27.94 W. The defect concentration and conductivity of the green billets for TiO_(2) and 3YSZ were also changed by the DBD, and then the FS process was modified. It is a new technology to treat the green billet of ceramics in very short time, applicable to other ceramics, and beneficial to regulate the FS process.

关键词： flash sintering(FS) ZnO dielectric barrier discharge(DBD) oxygen vacancy OV defect engineering

Nonexistence of cross-term free time-frequency distribution with concentration of Wigner-Ville distribution

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Science in China(Series F) 2002年第3期45卷 174-180页

作者：邹红星卢旭光戴琼海李衍达 Department of Automation Tsinghua University Beijing 100084 China

Wigner-Ville distribution (WVD) is recognized as being a powerful tool and a nucleus in time-frequency representation (TFR) which gives an excellent time-frequency concentration, and more importantly, has many desirable properties. A major shortcoming of WVD is the inherent cross-term (CT) interference. Although solutions to this problem from the bulk of contributions to the literature concerning TFR are currently available, none has been able to completely eliminate the CT’s in WVD. It is therefore a common belief that if there exists an auxiliary time-frequency distribution (TFD) which has the same auto-terms (AT’s) as that in WVD, but has CT’s with the opposite sign, then, by adding the auxiliary TFD to WVD, an ideal TFD, which preserves the concentration of WVD while annihilating the CT’s, is readily obtained. However, we prove that the auxiliary TFD does not exist. Moreover, it is found that in general, CT free joint distributions with their concentrations close to that of WVD do not exist either.

关键词： time-frequency analysis Wigner-Ville distribution cross-term cancellation.

Design methods of rhombic tensegrity structures

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Acta Mechanica Sinica 2010年第4期26卷 559-565页

作者： Xi-Qiao Feng Yue Li Yan-Ping Cao Shou-Wen Yu Yuan-Tong Gu AML Department of Engineering Mechanics Tsinghua University Beijing 100084 China School of Engineering Systems Queensland University of Technology GPO Box 2434 Brisbane QLD 4001 Australia

As a special type of novel flexible structures, tensegrity holds promise for many potential applications in such fields as materials science, biomechanics, civil and aerospace engineering. Rhombic systems are an important class of tensegrity structures, in which each bar constitutes the longest diagonal of a rhombus of four strings. In this paper, we address the design methods of rhombic structures based on the idea that many tensegrity structures can be constructed by assembling one-bar elementary cells. By analyzing the properties of rhombic cells, we first develop two novel schemes, namely, direct enumeration scheme and cell-substitution scheme. In addition, a facile and efficient method is presented to integrate several rhombic systems into a larger tensegrity structure. To illustrate the applications of these methods, some novel rhombic tensegrity structures are constructed.

关键词： Tensegrity Structural design Assembling method Flexible structure

An upgraded scheme of surface physics for Antarctic ice sheet and its implementation in the WRF model

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Science Bulletin 2016年第7期61卷 576-584页

作者： Yao Yao Jianbin Huang Yong Luo Zongci Zhao Ministry of Education Key Laboratory for Earth System Modeling Center for Earth System Science and Joint Center for Global Change Studies Tsinghua University

Regional climate models often lack detailed description of ice sheet surface and, as a result, are limited in their capability to provide useful information for Antarctic climate research and field campaigns. In this study, an upgraded scheme of surface physics for Antarctic ice sheet(IST) is developed to improve the surface temperature simulations in Antarctica. Through stand-alone simulations, IST shows advantages over the Noah glacial module, a commonly utilized scheme in the widely used Weather research and Forecasting(WRF) model. These improvements are mainly attributed to the incorporation of detailed snow physics and optimized surface layer parameterization, which results in better simulations of both the surface albedo in summer and the turbulent sensible heat flux in winter. When coupled with IST instead of Noah,WRF models show improved simulation of surface temperatures throughout the year. The bias and root-meansquare-error of annual mean surface temperatures are reduced from 5.7 and 6.0 to 0.2 and 2.7 K.

关键词： Regional climate model Antarctica Surface temperature Ice sheet

Characteristics of Zn^(2+) Biosorption by Saccharomyces cerevisiae

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Biomedical and Environmental Sciences 2007年第6期20卷 478-482页

作者： CAN CHEN JIAN-LONG WANG Laboratory of Environmental Technology INET Tsinghua University Beijing 100084 China

Objective To investigate the characteristics of Zn^2＋ biosorption and the release of cations during the process of Zn^2＋ biosorption by intact cells of Saccharomyces cerevisiae. Methods The batch adsorption test was used to study the biosorption equilibrium and isotherm. Zn^2＋ concentration was measured with atomic adsorption spectrophotometer （AAS） AAS ***. Results When the initial concentration of Zn^2＋ ranged between 0.08 and 0.8 retool/L, the initial pH was natural （about 5.65）, the sorbent concentration was about 1 g/L and the capacity ofZn〉 biosorption was from 74.8 to 654.8 μmol/g. The pH value increased by 0.55-1.28 and the intracellular cations （K^＋, Mg^2＋, Na^＋, Ca〉） of the cells were re/eased during the process of Zn〉 biosorption. Conclusion Ion exchange was one of the mechanisms for Zn^2＋ biosorption. The biomass of Saccharomyces cerevisiae is a potential biosorbent for the removal of Zn^2＋ from aqueous solution. More work needs to be done before putting it into practical application.

关键词： Saccharomyces cerevisiae Biosorption Zinc ion Cation release

Integral Formulas for Compact Spacelike Hypersurfaces in de Sitter Space and their Applications to Goddard's Conjecture

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Acta Mathematica Sinica,English Series 1998年第2期14卷 285-288页

作者： Li Haizhong (Department of Applied Mathematics,tsinghua University,Beijing 100084,China)(Email:hli@***)Chen Weihuan (Department of Mathematics,Peking University,Beijing 100871,China)(Email:whchen@sxx0.math.pku,***) Department of Applied Mathematics Tsinghua University Beijing China Department of Mathematics Peking University Beijing China

We establish integral formulas of Minkowski’s type for compact spacelike hypersurfaces in de sitter space S1n+1（1）and give their applications to the case of constant r-th mean curvature （r=1,2,…,n-1）.When r=1 we... 详细信息

关键词： Spacelike hypersurfaces de Sitter space Goddard’s conjecture

A new sintering approach to ceramics at low temperature from Ba(ZrxTi1-x)O3 nanoparticles doped by ZnO

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Journal of Advanced Ceramics 2016年第4期5卷 277-283页

作者： Rui GUO Jianquan QI Jiali LUO Xiaoyu DONG Longtu LI School of Nature Resources & Materials Science Northeastern University at QinhuangdaoQinhuangdao Hebei 066004 China State Key Laboratory of Fine Ceramics and New Processing Tsinghua University Beijing 100084 China

The sintering temperature decreases theoretically with the grain size of the ceramic powders,but it is not always right for fine grain sized nanopowders due to the inevitable agglomerations,and thus pores are hard to eliminate thoroughly during *** overcome this difficulty,a new approach is designed to sintering ceramics at low temperature from *** this scheme,excessive dopants,such as ZnO,are synthesized into the nanoparticles,and they would be liberated again on the surfaces of the grains at high temperature as sintering aids homogenously to promote ***,we compared the ceramic sintering of ZnO-doped barium zirconate titanate (BaZrxTil-xO3,BZT) nanoparticles with BZT nanoparticles using ZnO as additive at 1150 ℃.Both kinds of nanoparticles were directly synthesized by the same process at room temperature and yielded the same initial grain size of～10 *** dense BZT ceramic with relative density of 99％ was fabricated from the 2 mol％ ZnO-doped *** the other hand,the porous BZT ceramic with density of 78％ was obtained from nanoparticles with 2 mol％ ZnO as ***,our strategy to ceramic sintering at low temperature from nanoparticles was confirmed.

关键词： barium zirconate titanate (BaZrxTi1-xO3,BZT) nanopowder direct synthesis sintering