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Journal of Systems Science & Complexity 2009年第1期22卷 137-149页

作者： juan zhao Yunmin ZHU Department of Electronic Engineering Beijing Institute of Technology Beijing 100081 China. Department of Mathematics Sichuan University Chengdu 610064 China.

The optimally weighted least squares estimate and the linear minimum variance estimateare two of the most popular estimation methods for a linear *** this paper,the authors makea comprehensive discussion about the relationship between the two ***,the authorsconsider the classical linear model in which the coefficient matrix of the linear model is deterministic,and the necessary and sufficient condition for equivalence of the two estimates is ***,under certain conditions on variance matrix invertibility,the two estimates can be identical providedthat they use the same a priori information of the parameter being ***,the authorsconsider the linear model with random coefficient matrix which is called the extended linear model;under certain conditions on variance matrix invertibility,it is proved that the former outperforms thelatter when using the same a priori information of the parameter.

关键词： Conditional expectation linear minimum variance estimation necessary and sufficient condition optimally weighted least squares estimation.

Medical Sign Recognition of Lung Nodules Based on Image Retrieval with Semantic Features and Supervised Hashing

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Journal of Computer Science & Technology 2017年第3期32卷 457-469页

作者： juan-juan zhao Ling Pan Peng-Fei zhao Kiao-Xian Tang College of Computer Science and Technology Taiyuan University of Technology Taiyuan 030024 China Shanxi Provincial People's Hospital Taiyuan 030012 China

Sign recognition is important for identifying benign and malignant nodules. This paper proposes a new sign recognition method based on image retrieval for lung nodules. First, we construct a deep learning framework to extract semantic features that can effectively represent sign information. Second, we translate the high-dimensional image features into compact binary codes with principal component analysis （PCA） and supervised hashing. Third, we retrieve similar lung nodule images with the presented adaptive-weighted similarity calculation method. Finally, we recognize nodule signs from the retrieval results, which can also provide decision support for diagnosis of lung lesions. The proposed method is validated on the publicly available databases： lung image database consortium and image database resource initiative （LIDC-IDRI） and lung computed tomography （CT） imaging signs （LISS）. The experimental results demonstrate our retrieval method substantially improves retrieval performance compared with those using traditional Hamming distance, and the retrieval precision can achieve 87.29%when the length of hash code is 48 bits. The entire recognition rate on the basis of the retrieval results can achieve 93.52%. Moreover, our method is also effective for real-life diagnosis data.

关键词： lung nodule medical sign recognition image retrieval supervised hashing adaptive weight

Research on the measurement of the price change of telecom services in China

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The Journal of China Universities of Posts and Telecommunications 2006年第3期13卷 110-113页

作者： zhao Hui-juan Management Department Xi'an University of Posts and TelecommunicationsXi'an 710061 China

It is difficult to measure the total change of the telecom service price （TSP） in China due to the complexity of TSP and the diversity of telecom service. This article analyzes the relation between telecom service revenue and traffic volumes of telecom service and deduces the method of measuring the total change in tendency of telecom price, which is based on the consumer＇s actual payment for telecom services. After describing the changing trend of TSP with the time series data from 1949 to 2000, the TSP showed a continuous declining tendency during 1949～1975. In contrast, the TSP showed a rising tendency from 1976 to 1991 and a sharp declining trend after 1992. Empirical tests and actual background of telecom reform support the results.

关键词： price telecom service price revenue traffic volumes of telecom service

Sun's total irradiance reconstruction based on multiple solar indices

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Science China(Physics,Mechanics & Astronomy) 2012年第1期55卷 179-186页

作者： zhao juan HAN YanBen Department of Astronomy Beijing Normal University Beijing 100875 China National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

In order to uncover a possible influence on the Earth's climate, we need a much longer time series, i.e., the total solar irradiance (TSI) which is also an interesting issue in its own right in solar physics. By comparing different solar indices associated with TSI during the period 1979 to 2009, several empirical models in the TSI are presented. We verify that the reconstruction model based on the three variables: sunspot number, sunspot area, and solar 10.7 cm radio flux, is the best one. As demonstrated by model calculations, the history of TSI was reconstructed back to 1947 based on 3-indices and to 1874 based on 2-indices, respectively. The reason that the reduced irradiance on the trough during 2006 to 2009 lasts long may be due to the about 85-year cycle of solar activity, which modulates the intensity of the 11-year cycle (Schwabe cycles), possesses a considerable potential to produce an effective reducing, and holds on a steadily lower level of irradiance.

关键词： solar total irradiance sunspot number sunspot area solar 10.7 cm radio flux reconstruction

Improved RIP-based performance guarantees for multipath matching pursuit

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Science China(Information Sciences) 2018年第10期61卷 173-186页

作者： juan zhao Xia BAI Ran TAO School of Information and Electronics Beijing Institute of Technology Beijing Key Laboratory of Fractional Signals and Systems Beijing Institute of Technology

The multipath matching pursuit(MMP) is a generalization of the orthogonal matching pursuit(OMP), which generates multiple child paths for every candidate in each iteration and selects the candidate having the minimal residual as the final support set when iteration ends. In this paper we analyze its performance in both noiseless and noisy cases. The restricted isometry property(RIP)-based condition of MMP that ensures accurate recovery of sparse signals in the noiseless case is derived by using a simple technique. The performance guarantees of the MMP for support recovery in noisy cases are also *** is shown that under certain conditions on the RIP and minimum magnitude of nonzero components of the sparse signal, the MMP will exactly recover the true support of the sparse signal in cases of bounded noises and recover the true support with a high probability in the case of Gaussian noise. Our bounds on the RIP improve the existing results.

关键词： compressed sensing(CS) sparse signal reconstruction multipath matching pursuit(MMP) support recovery restricted isometry property(RIP)

Wheat straw return can lead to biogenic toluene emissions

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Journal of Environmental Sciences 2023年第2期124卷 281-290页

作者： Ting Wu Xiaoyu zhao Mengdi Liu juan zhao Xinming Wang School of Ecology and Environment Anhui Normal UniversityWuhu 241000China Center of Cooperative Innovation for Recovery and Reconstruction of Degraded Ecosystem in Wanjiang City Belt Wuhu 241000China State Key Laboratory of Organic Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China

As a common practice in agricultural system,straw return has been reported to release a large number of trace gases and attractedmuch ***,the role of straw return in toluene emission remains poorly *** this study we measured the emissions of toluene as well as other 50 volatile organic compounds(VOCs)from wheat straw return for 66 days under flooded and non-flooded conditions,*** results showed that substantial toluene was released from the returned wheat straw particularly under flooded condition,and primarily derived from the secondary *** emissions from the returned wheat straw were 36.8 and 8.45 mg C/kg,sharing 28.0%and 8.6%of total VOCs released,and over 90% of toluene emissions occurred between days 24-56 and 0-17 under flooded and non-flooded conditions,*** emission rates of toluene were relatively high but decreased sharply at the beginning 2 days,and then was steady until 24 days under the two moisture *** the initial decrease these rose again to form one“peak emission window”between days 24-56 under flooded condition,while these were still very low and steady until the end under non-flooded *** toluene emission rates significantly positively correlated with microbial biomass C under flooded condition,but negatively associated with bacteria and fungus number,microbial biomass C,and CO_(2) flux under non-flooded condition,suggesting that microorganism might play an important role in toluene emissions from wheat straw return.A rough estimate indicated that straw return might be important for biogenic toluene.

关键词： Toluene Boigenic volatile organic compounds(BVOCs) Emission profile Straw return

A study of short-period variation in solar activity

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Research in Astronomy and Astrophysics 2014年第8期14卷 1011-1018页

作者： Ji-Long Chen juan zhao Department of Astronomy Beijing Normal University

We introduce two methods to detect short-period variation in solar activity. These are called amplitude of low frequency fluctuation （ALFF） and fractional am- plitude of low frequency fluctuation （FALFF）. We find a positive correlation between short-period variation and 11-year variation of solar activity using these two methods. Through ALFF, we find that solar activity over a short period becomes intensive when the 11-year solar activity is intensive. The ALFF value of the short period activity varies with the peak in sunspot number as a quadratic function. Through FALFF we find that the ratio of short-period spectral intensity to intensity over the whole period of solar activity will increase when the 11-year period of solar activity is intensive. The short-period FALFF value varies with the peak in sunspot number according to a cubic function. Using ALFF, we obtain a yearly series of solar activity that varies over a short period of 1-5 yr from 1860 to 2003, which shows an obvious periodicity of about 22 yr, 33 yr, 11 yr and a century. These short period variations show good correlations with long term variations in solar activity.

关键词： Sun activity -- Sun sunspots -- methods data analysis

Enhanced photogalvanic effect in the two-dimensional MgCl_(2)/ZnBr_(2) vertical heterojunction by inhomogenous tensile stress

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Frontiers of physics 2022年第1期17卷 177-182页

作者： Liyu Qian juan zhao Yiqun Xie Department of Physics Shanghai Normal University100 Guilin RoadShanghai200234China

The photogalvanic effect (PGE) occurring in noncentrosymmetric materials enables the generation of a dc photocurrent at zero bias with a high polarization sensitivity, which makes it very attractive in photodetection. However, the magnitude of the PGE photocurrent is usually small, leading to a low photoresponsivity, and therefore hampers its practical application in photodetection. Here, we propose an approach to largely enhancing the PGE photocurrent by applying an inhomogenous mechanical stretch, based on quantum transport simulations. We model a two-dimensional photodetector consisting of the wide-bandgap MgCl_(2)/ZnBr_(2) vertical van der Waals heterojunction with the noncentrosymmetric C_(3v) symmetry. Polarization-sensitive PGE photocurrent is generated under the vertical illumination of linearly polarized light. By applying inhomogenous mechanical stretch on the lattice, the photocurrent can be largely increased by up to 3 orders of magnitude due to the significantly increased device asymmetry. Our results propose an effective way to enhance the PGE by inhomogenous mechanical strain, showing the potential of the MgCl_(2)/ZnBr_(2) vertical heterojunction in the low-power UV photodetection.

关键词： photogalvanic effect mechanical stretch polarization-sensitive vertical heterojunction ultraviolet photodetection

Quasi-classical trajectory approach to the stereo-dynamics of the reaction F+HO→HF+O

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Science China Chemistry 2010年第4期53卷 927-932页

作者： juan zhao Yan Xu Xian zhao QingTian Meng 1. College of Physics and Electronics Shandong Normal University Jinan 250014 China2. State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

Quasi-classical trajectory (QCT) calculations are employed for the reaction F + HO(0,0)→HF + O based on the adiabatic potential energy surface (PES) of the ground 3A″triplet state. The average rotational alignment factor as a function of collision energy and the four polarization dependent generalized differential cross sections have been calculated in the center-of-mass (CM) frame, separately. The distribution P(θr) of the angle between k and j′, the distribution P(θr) of dihedral angle denoting k-k′-j′ correlation, and the angular distribution P(θr, Φr) of product rotational vectors in the form of polar plots are calculated as well. The effect of Heavy-Light-Heavy (HLH) mass combination and atom F’s relatively strong absorbability to charges on the alignment and the orientation of product molecule HF rotational angular momentum vectors j′ is revealed.

关键词： product polarization F + HO reaction quasi-classical trajectory vector correlations

Optimization of the transmission mechanism for wireless TCP

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The Journal of China Universities of Posts and Telecommunications 2008年第1期15卷 38-42页

作者： QU zhao-wei ZHANG juan Beijing University of Posts and Telecommunications Beijing 100876 China

A novel method which can detect the possible handoffs for mobile nodes is proposed in this article. The method can be deployed on mobile nodes. So when a possible handoff occurs, mobile nodes can detect and take some necessary actions in time. In this study, the method is also used to optimize the transmission mechanism of Q-TCP. Moreover, the simulation results show that Q-TCP can provide better quality of service （QoS） for mobile nodes when they are moving among different agents.

关键词： wireless TCP data stream handoff QoS