检索结果-南通市图书馆

Thermal Characterization and Decomposition Kinetics of Free Anthraquinones from Rhubarb

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

Chinese Chemical Letters 2006年第5期17卷 699-702页

作者： Li Ming ZHANG Xia LI Yu jie dai College of Bioengineering Tianjin University of Science ＆ Technology Tianjin 300222

The thermal behaviour of aloe-emodin, chrysophanol and physcion and their kinetics have been investigated under non-isothermal conditions by means of differential thermal analysis （DTA） and thermogravimetry （TG）. The thermal characteristics have been determined using the DTA and TG-DTG curves. The non-isothermal kinetic data were analyzed by means of the Achar method and the Madhusudanan-Krishnan-Ninan （MKN） method. The possible reaction mechanisms have been investigated by comparing the kinetic parameters. The kinetic equation for aloe-emodin, chrysophanol and physcion can be expressed as dα/dt=Aexp（-E/RT）1/3（1-α）[-In（1-α]2. The activation energy E （kJ mol^-1） of the three free anthraquinones are 78.09, 89.54, and 107.5 and their InA/s^-1 are 22.98, 36.85 and 43.60, respectively.

关键词： Aloe-emodin chrysophanol physcion thermogravimetry (TG) differential thermoanalysis (DTA) non-isothermal kinetics.

Scheme to Implement Optimal Asymmetric Economical Phase-Covariant Quantum Cloning in Cavity QED

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2008年第6期49卷 1473-1476页

作者： ZHANG Wen-Hai dai jie-Lin YE Liu School of Physics and Material Science Anhui University Hefei 230039 China Department of Physics ＆ Electronic Engineering Hefei Teachers College Hefei 230061 Chine

We propose an experimentally feasible scheme to implement the optimal asymmetric economical 1→2 phase-covariant quantum cloning in two dimensions based on the cavity QED technique. The protocol is very simple and only two atoms are required. Our scheme is insensitive to the cavity field states and cavity decay. During the processes, the cavity is only virtually excited and it thus greatly prolongs the efficient decoherent time. Therefore, it may be realized in experiment.

关键词： optimal asymmetric economical phase-covariant cloning cavity QED

ESL-SELO:A Robust Image Denoising Algorithm with Penalty

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2017年第3期33卷 753-770页

作者： Guo-hua WANG San-guo ZHANG Peng-jie dai School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Big Data Mining and Knowledge Management Chinese Academy of SciencesBeijing100049China School of Business Remin University of ChinaBeijing 100872China

Robust image recovery methods have been attracted more and more attention in recent decades for its good property of tolerating system errors or measuring noise. In this paper, we propose a new robust method （ESL-SELO） to recover nosing image, which combine exponential loss function and seamless-L0 （SELO） penalty function to guarantee both accuracy and robustness of the estimator. Theoretical result showed that our method has a local optimal solution and good asymptotic properties. Finally, we compare our method with other methods in simulation which shows better robustness and takes much less time.

关键词： denoising algorithm penalty function robust SELO

Variable Selection of Generalized Regression Models Based on Maximum Rank Correlation

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2014年第3期30卷 833-844页

作者： Peng-jie dai Qing-zhao ZHANG Zhi-hua SUN School of Business Renmin University of China Department of Mathematics University of Chinese Academy of Sciences

In this paper, we investigate the variable selection problem of the generalized regression models. To estimate the regression parameter, a procedure combining the rank correlation method and the adaptive lasso technique is developed, which is proved to have oracle properties. A modified IMO （iterative marginal optimization） algorithm which directly aims to maximize the penalized rank correlation function is proposed. The effects of the estimating procedure are illustrated by simulation studies.

关键词： maximum rank correlation estimation adaptive LASSO oracle properties generalized regression models.

Identification of candidate millisecond pulsars from Fermi LAT observations Ⅱ

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2017年第7期17卷 89-98页

作者： Xue-jie dai Zhong-Xiang Wang Jithesh Vadakkumthani Yi Xing Shanghai Astronomical Observatory Chinese Academy of Sciences University of Chinese Academy of Sciences

On the basis of the properties of known γ-ray millisecond pulsars（MSPs）, we have selected 77un-associated sources from the Fermi Large Area Telescope（LAT） third source catalog for the purpose of finding likely candidate MSPs. Previously, detailed LAT data analysis for 39 of them was reported,and here we report the analysis for the remaining 38 sources. We identify that among the 38 sources, 28 of them are single point-like sources with clean background and their spectra show significant *** also conduct an analysis of archival X-ray data available for 24 of the 28 sources. In the fields of10 sources, there is at least one X-ray object, and in those of the other 14 sources, no X-ray object is detected but this is probably due to the X-ray observations being short. We discuss the possible MSP nature for these sources. Six of them（J0514.6-4406, J1035.7-6720, J1624.2-4041, J1744.1-7619,J1946.4-5403 and J2039.6-5618） are most likely associated with pulsars because of multi-wavelength identifications including direct radio or γ-ray detection of pulsations. To firmly establish the associations or verify the MSP nature for other sources, deep X-ray and/or optical observations are needed.

关键词： stars pulsars - stars binaries - gamma rays stars

Identification of candidate millisecond pulsars from Fermi LAT observations

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2016年第6期16卷 113-122页

作者： Xue-jie dai Zhong-Xiang Wang Jithesh Vadakkumthani Yi Xing Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China University of Chinese Academy of Sciences Beijing 100049China

We report our detailed data analysis of 39 γ-ray sources selected from the 992 unassociated sources in the third Fermi Large Area Telescope Third Source Catalog. The selection criteria, which were set for finding candidate millisecond pulsars （MSPs）, are non-variables with curved spectra and 〉5° Galactic latitudes. From our analysis, 24 sources were found to be point-like sources not contaminated by back- ground or nearby unknown sources. Three of them, Jl544.6-1125, J1625.1-0021 and J1653.6-0158, have been previously studied, indicating that they are likely MSPs. The spectra of J0318.1＋0252 and J2053.9＋2922 do not have properties similar to known γ-ray MSPs, and we thus suggest that they are not MSPs. Analysis of archival X-ray data for most of the 24 sources was also conducted. Four sources were found with X-ray objects in their error circles, and 16 with no detection. The ratios between the γ-ray fluxes and X-ray fluxes or flux upper limits are generally lower than those of known γ-ray MSPs, suggesting that if the γ-ray sources are MSPs, none of the X-ray objects are their counterparts. Deep X-ray or radio observations of these sources are needed in order to identify their MSP nature.

关键词： stars pulsars -- stars binaries -- gamma rays stars

ICM method for topology optimization of multimaterial continuum structure with displacement constraint

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2019年第3期35卷 552-562页

作者： Hong-Ling Ye Zong-jie dai Wei-Wei Wang Yun-Kang Sui College of Mechanical Engineering and Applied Electronics Technology Beijing University of TechnologyBeijing 100124China

A new topology optimization method is formulated for lightweight design of multimaterial structures, using the independent continuous mapping (ICM) method to minimize the weight with a prescribed nodal displacement constraint. Two types of independent topological variable are used to identify the presence of elements and select the material for each phase, to realize the interpolations of the element stiffness matrix and total weight. Furthermore, an explicit expression for the optimized formulation is derived, using approximations of the displacement and weight given by first- and second-order Taylor expansions. The optimization problem is thereby transformed into a standard quadratic programming problem that can be solved using a sequential quadratic programming approach. The feasibility and effectiveness of the proposed multimaterial topology optimization method are demonstrated by determining the best load transfer path for four numerical examples. The results reveal that the topologically optimized configuration of the multimaterial structure varies with the material properties, load conditions, and constraint. Firstly, the weight of the optimized multimaterial structure is found to be lower than that composed of a single material. Secondly, under the precondition of a displacement constraint, the weight of the topologically optimized multimaterial structure decreases as the displacement constraint value is increased. Finally, the topologically optimized multimaterial structures differ depending on the elastic modulus of the materials. Besides, the established optimization formulation is more reliable and suitable for use in practical engineering applications with structural performance parameters as constraint.

关键词： Independent continuous mapping method Multimaterial Topology optimization Continuous structure

Controlled Synthesis LaPO4 Nanorods via a Hydrothermal Route

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

Controlled Synthesis LaPO4 Nanorods via a Hydrothermal Route

Solvothermal Syntheses of (H_2en)_2Sn_2S_6·en and[(H_2hmda)_3(Hhmda)_2](Sn_2S_6)_2Using SnCl_4 and S_8 as Starting Materials

第八届中国功能材料及其应用学术会议

作者： dai jie LIU Kai-li LI Xia College of Materials Science and Technology Qingdao University of Science & Technology

ISBN: (纸本)9783037859698

LaPO nanorods have been selectively synthesized via a hydrothermal route,using La(NO) ·6HO and NaHPO as raw materials,without using any catalyst or template.X-ray diffraction(XRD),scanning electron microscopy(SEM),IR spectra(IR)and photo-luminescence(PL) spectra were used to characterize the as-prepared *** morphological changes of the products due to the different mole ratios of La(NO)·6HO and NaHPO were *** effect of the thermal treatment on the structure of the LaPO nanorods was also *** addition,the emission intensity of LaPO nanorods with different Eu doped concentration was compared and discussed.

关键词： Hydrothermal route Nanorods Luminescence Lanthanum phosphate

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2005年第10期24卷 1157-1163页

作者： JIA Ding-Xian dai jie ZHU Qin-Yu LU Wen GUO Wen-Juan Department of Chemistry and Chemical Engineering Suzhou University Suzhou 215006 China State Key Laboratory of Coordination Chemistry Nanjing University Nanjing 210093 China

Three thiostannates （H2en）2Sn2S6· en 1, （Hen）4Sn2S6 2 （en = ethylenediamine, a known compound）and [（H2hmda）3（Hhmda）2]（Sn2S6）2 3 （hmda = hexamethylenediamine） were prepared using SnCl4.5H2O and S8 as starting materials in alkylenediamine solutions under mild solvothermal conditions. Compound 1 crystallizes in the triclinic system, space group P1^- with a = 8.7491（17）, b = 10.704（2）, c = 12.2031（19） A, a = 74.888（13）, β= 72.998（12）, γ= 89.032（15）°, V = 1052.9（3） A^3, Mr = 614.08, Z= 2, De = 1.937 g/cm^3, p = 2.966 mm^-1, F（000） = 604, S = 1.211, R = 0.0579 and wR = 0.0770 for 3999 observed reβections with I 〉 2σ（I）; while 3 crystallizes in the triclinic system, space group P1^- with a = 9.8075（13）, b = 10.8266（16）, c = 14.303（2） A, a = 88.611 （10）, β = 81.030（9）, γ = 74.609（9）°, V = 1446.1 （4） A^3, Mr = 1448.78, Z = 1, Dc = 1.664 g/cm^3, μ = 2.173 mm^-1, F（000） = 730, S = 1.173, R = 0.0457 and wR = 0.0667 for 5738 observed reβections with I 〉 2σ（I）. The compounds are composed of dimeric [Sn2S6]^4- anions and protohated alkylenediamine cations.

关键词： solvothermal synthesis thiostannate crystal structure hydrogen bond diamine