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Exact distribution of MLE of covariance matrix in a GMANOVA-MANOVA model

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science china Mathematics 2005年第12期48卷 1597-1608页

作者： BAI Peng Department of Statistics University of YunnanKunming 650091China

For a GMANOVA-MANOVA model with normal error: Y = XB1Z1 T +B2Z2 T+ E, E- Nq×n(0, In (?) ∑), the present paper is devoted to the study of distribution of MLE, ∑, of covariance matrix ∑. The main results obtained are stated as follows: (1) When rk(Z) -rk(Z2) ≥ q-rk(X), the exact distribution of ∑ is derived, where z = (Z1,Z2), rk(A) denotes the rank of matrix A. (2) The exact distribution of |∑| is gained. (3) It is proved that ntr{[S-1 - ∑-1XM(MTXT∑-1XM)-1MTXT∑-1]∑}has X2(q_rk(x))(n-rk(z2)) distribution, where M is the matrix whose columns are the standardized orthogonal eigenvectors corresponding to the nonzero eigenvalues of XT∑-1X.

关键词： GMANOVA-MANOVA model,MLE,distribution,hypergeometric function.

Least-squares reverse-time migration for reflectivity imaging

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science china Earth sciences 2015年第11期58卷 1982-1992页

作者： YAO Gang WU Di Department of Earth science and Engineering Imperial College London The Unconventional Natural Gas Institute China University of Petroleum (Beijing)

A least-squares reverse-time migration scheme is presented for reflectivity imaging. Based on an accurate reflection modeling formula, this scheme produces amplitude-preserved stacked reflectivity images with zero phase. Spatial preconditioning, weighting and the Barzilai-Borwein method are applied to speed up the convergence of the least-squares inversion. In addition, this scheme compensates the effect of ghost waves to broaden the bandwidth of the reflectivity images. Furthermore, roughness penalty constraint is used to regularize the inversion, which in turn stabilizes inversion and removes high-wavenumber artifacts and mitigates spatial aliasing. The examples of synthetic and field datasets demonstrate the scheme can generate zerophase reflectivity images with broader bandwidth, higher resolution, fewer artifacts and more reliable amplitudes than conventional reverse-time migration.

关键词： adjoint migration least-squares reverse-time migration cross-correlation imaging condition deconvolution imagingcondition deghost

Scanning Tunneling Microscopy Investigation of Bainite in Steel

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Chinese science Bulletin 1994年第10期39卷 797-800页

作者：严隽珏于洪滨李志钢盖铮杨威生方鸿生王家军杨志刚邓旭蕊 Department of Physics Peking University Beijing 100871 PRC Department of Materials science and Engineering Tsinghua University Beijing 100084 PRC

Bainite, which is formed in metals, alloys, or even non-metallic materials under certainconditions, is a kind of very important phase transformation product. Since bainiteplays an important role in steel, this kind of steel is named bainite steel. In the pastdecades scientists did a lot of research work on the bainite structure and its phasetransformation mechanism. But due to its complexity in nature and the limitationsof the observation methods, at present the study in this aspect is still in theexploring stage both theoretically and experimentally, and many problems remain to besolved. There have long been two controversial views on the phase transformationmechanism, i.e. 'shear' mechanism and 'diffusion' mechanism, also calledledge-growth mechanism. The two opinions are mainly based on the observations ofbainite morphologies or structures by means of SEM or TEM, the measurements

关键词： STM bainite ferrite super-subunit.

A Novel Method for the Preparation of Octyl Bonded Styrene-divinylbenzene HPLC Packings

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Chinese Chemical Letters 2005年第10期16卷 1379-1382页

作者： Yu LIU Shan Wei WANG Yu Min ZUO Department of Chemistry Nankai University Tianjin 300071 Department of Chemistry Tianjin University Tianjin 300072 Central Laboratory Nankai University Tianjin 300071

Monodisperse octyl bonded poly（styrene-divinylbenzene）（C8-PS-DVB） beads were prepared via a single-step swelling and polymerization method. Fourier transform infrared and chromatographic evaluation were used to c... 详细信息

关键词： Monodisperse C8-PS-DVB single-step swelling and polymerization.

A new approach for B-cell epitope prediction in viral proteins

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Chinese science Bulletin 1995年第9期40卷 761-767页

作者：吴玉章朱锡华 Department of Immunology The Third Medical University Chongqing 630038 China

Prediction of epitopes in viral proteins is helpful for the design of immunogenicpeptides, new generation of vaccines and diagnostic reagents. Unfortunately, there are atleast two constraints on the interpretation of the earlier predictive methods. In the firstplace, the earlier plots were based on experimental findings in general proteins, and

关键词： epitope prediction viral protein antigenicity value.

Effects of additives on the aggregation of surfactants: binding domination

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Chinese Journal of Chemistry 1992年第3期10卷 237-244页

作者： LEI, Xue-Gong Department of Chemistry, Lanzhou University, Lanzhou 730000 Department of Chemistry Lanzhou University Lanzhou 730000

The effects of electrolytes, alcohols, and urea on the aggregation of SDS, CTAB, and Triton X-100 at 25℃ have been investigated by fluorescence probing of pyrene. Both electrolytes and alcohols reduce the critical micelle concentration (CMC) of the ionic surfactants, while the effect of the former is more pronounced. It is shown that the effects of electrolytes mainly depend on the concentrations and especially the valence of the opposite charge ions, and only slightly depend on the same charge ions in respect of ion aggregate of micelle. The logarithm of CMC is not linearly correlated with the concentrations of the counter ion or the electrolytes. The results are rationalized in terms of Hartley's model. Propanol increases the CMC of TX-100, while electrolytes and urea do not. In all the three kinds of surfactant micelles the excitation spectrum of pyrene slightly red-shifts (ca. 4 nm) from that in water, but is not affected by the additives. The micropolarity of the environment in which pyrene molecule resides in SDS micelle decreases with the increase of the concentrations of electrolytes. This is not the case when alcohols and urea were added to SDS or to TX-100. It is suggested that the addition of electrolytes would result in more orderly orientation of SDS molecules. It is the binding strength of the counter ions that dominates the effects of additives on the aggregation of surfactants.

关键词： CMC binding domination Effects of additives on the aggregation of surfactants

Synthetic and structural chemistry of nickel(Ⅱ) complexes containing dithiolato and phosphine ligands Ⅰ. Preparation and crystal structure of Ni_2(PPh_3)_2(edt)_2

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Chinese Journal of Chemistry 1992年第3期10卷 227-231页

作者： CAO, Rong HUANG, Zhi-Ying LEI, Xin-Jian KANG, Bei-Sheng HONG, Mao-Chun LIU, Han-Qin Fuzhou Laboratory of Structural Chemistry and Fujian Institute of Research on the Structure of Matter. Chinese Academy of sciences, Fuzhou, Fujian 350002 Fuzhou Laboratory of Structural Chemistry and Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002

A nickel(Ⅱ) complex containing both dithiolato and phosphine ligands, Ni_2(PPh_3)_2(edt)_2 (edt = SCH_2CH_2S^(2-)), has been prepared and characterized by X-ray diffration. The complex crystallizes in the triclinic system, space group P-1, with a = 10.693(3), b = 17.457 (6), c = 10.606 (3)A, α= 102.84(2), β = 96.49 (2), γ = 82.56(3)°; V = 1906.8 A^3; D_c = ***^(-3) for Z=2; the final con- ventional R was 0.052 based on 3338 observed reflections. Nickel atoms are linked by two sulfur atoms from two edt ligands with the Ni--Ni distance of 2.893 A, and each Ni atom is coordinated by one phosphorus atom and three sulfur atoms with a square-planar geometry, where the average: length of Ni--S bond is 2.180 A and Ni--P bond 2.188 A. The UV-Vis and ~1H NMR spectra have also been recorded.

关键词： Synthetic and structural chemistry of nickel complexes containing dithiolato and phosphine ligands edt PPh3 Preparation and crystal structure of Ni2 Ni

Resistance spot welding of Ti_(40)Zr_(25)Ni_3Cu_(12)Be_(20) bulk metallic glass:experiments and finite element modeling

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Rare Metals 2017年第2期36卷 123-128页

作者： Gang Wang Yong-Jiang Huang Deodat Makhanlall Jun Shen School of Mechanical and Automotive Engineering Anhui Polytechnic University School of Materials science and Engineering Harbin Institute of Technology

The use of resistance spot welding（RSW）technology for joining Ti40Zr25Ni3Cu12Be20 metallic glass was *** microstructure obtained from the welded BMG sample was *** without precipitates was prepared with welding current of 5.0 kA for 2cycles.A fully coupled thermal-electrical-mechanical finite element model（FEM） was developed to complement the experimental *** simulated results agree well with the *** effects of key process parameters such as welding current and welding time on the evolvement and microstructure of the weldment were determined and ***,the critical cooling rate for preserving the amorphous state in the weld fusion zone is determined to be approximately 1×10^3 K·s^-1.

关键词： Metallic glasses Simulations Resistance spot welding Cooling rate

Halogen-doped phosphorescent carbon dots for grayscale patterning

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Light(science & Applications) 2022年第7期11卷 1464-1474页

作者： Yanfeng Liu Mahmoud Al-salihi Yong Guo Roman Ziniuk Songtao Cai Luwei Wang Yuan Li Zhigang Yang Dengfeng Peng Kai Xi Zhongfu An Xudong Jia Liwei Liu Wei Yan Junle Qu Center for Biomedical Photonics and College of Physics and Optoelectronic Engineering Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong ProvinceShenzhen UniversityShenzhen 518060China School of Chemistry and Chemical Engineering Nanjing University163 Xianlin RoadNanjing 210023China Key Laboratory of Flexible Electronics(KLOFE)and Institute of Advanced Materials(IAM) Nanjing Tech University(NanjingTech)30 South Puzhu RoadNanjing 211816China

Flexible organic materials that exhibit dynamic ultralong room temperature phosphorescence(DURTP)via photoactivation have attracted increasing research interest for their fascinating functions of reversibly writing-reading-erasing graphic information in the form of a long ***,due to the existence of a nonnegligible activation threshold for the initial exposure dose,the display mode of these materials has thus far been limited to binary *** resorting to halogen element doping of carbon dots(CDs)to enhance intersystem crossing and reduce the activation threshold,we were able to produce,for the first time,a transparent,flexible,and fully programmable DURTP composite film with a reliable grayscale display *** of promising applications in UV photography and highly confidential steganography were constructed,partially demonstrating the broad future applications of this material as a programmable platform with a high optical information density.

关键词： activation resort negligible