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Efficient Estimation of Longitudinal Data Additive Varying Coefficient Regression Models

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Acta Mathematicae Applicatae Sinica 2017年第2期33卷 529-550页

作者： shu liu School of Statistics and Information Shanghai University of International Business and Economics Shanghai 201620 China School of Statistics and Management Shanghai University of Finance and Economics Shanghai 200433 China

We consider a longitudinal data additive varying coefficient regression model, in which the coef- ficients of some factors （covariates） are additive functions of other factors, so that the interactions between different factors can be taken into account effectively. By considering within-subject correlation among repeated measurements over time and additive structure, we propose a feasible weighted two-stage local quasi-likelihood estimation. In the first stage, we construct initial estimators of the additive component functions by B-spline se- ries approximation. With the initial estimators, we transform the additive varying coefficients regression model into a varying coefficients regression model and further apply the local weighted quasi-likelihood method to estimate the varying coefficient functions in the second stage. The resulting second stage estimators are com- putationally expedient and intuitively appealing. They also have the advantages of higher asymptotic efficiency than those neglecting the correlation structure, and an oracle property in the sense that the asymptotic property of each additive component is the same as if the other components were known with certainty. Simulation studies are conducted to demonstrate finite sample behaviors of the proposed estimators, and a real data example is given to illustrate the usefulness of the proposed methodology.

关键词： additive vary-coefficient model longitudinal data modified Cholesky decomposition withinsubject correlation

Dynamical Suppression of Decoherence in Two-Qubit Quantum Memory

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Communications in Theoretical Physics 2005年第3X期44卷 459-462页

作者： liu Xiao-shu Department of Physics Tsinghua University Beijing 100084 China Key Laboratory for Quantum Information and Measurements Beijing 100084 China

In this paper, we have detailedly studied the dynamical suppression of the phase damping for the two-qubit quantum memory of Ising model by the quantum "bang-bang" technique. We find the sequence of periodic radiofrequency pulses repetitively to flip the state of the two-qubit system and quantitatively find that these pulses can be used to effectively suppress the phase damping decoherence of the quantum memory and freeze the system state into its initial state. The general sequence of periodic radio-frequency pulses to suppress the phase damping of multi-qubit of Ising model is also given.

关键词： decoherence suppression quantum memory bang-bang technique Ising model

Underwater Sonar Image Detection:A Novel Quantum-Inspired shuffled Frog Leaping Algorithm

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Chinese Journal of Electronics 2018年第3期27卷 588-594页

作者： WANG Xingmei liu shu LI Qiming liu Zhipeng College of Computer Science and Technology Harbin Engineering University College of National Secrecy Harbin Engineering University Institute of Computing Technology Chinese Academy of Sciences

Object detection plays an important role in the underwater object recognition technology of sonar equipment. We propose a Novel quantum-inspired shuffled frog leaping algorithm(NQSFLA) to obtain more accurate detection results in this paper. The proposed NQSFLA adopts a fitness function combining intra-class difference with inter-class difference to evaluate the frog position more accurately and a new quantum evolution update strategy to improve the searching ability in the searching process. In order to avoid the disadvantages of Quantuminspired shuffled frog leaping algorithm(QSFLA), a fuzzy membership matrix with spatial information model is developed, which can remove isolated regions and further improve the detection accuracy. Segmentation, distribution and noise entropy(SDNE) model is also proposed to quantitatively evaluate the detection results. The detection results of the original sonar images demonstrate the effectiveness and adaptability of the proposed method.

关键词： Quantum-inspired shuffled frog leaping algorithm(QSFLA) Underwater sonar image Fitness function Update strategy Fuzzy membership matrix

Gravitational wave sensitivity curve of pulsar timing arrays affected by correlated noises

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Research in Astronomy and Astrophysics 2020年第11期20卷 293-302页

作者： shu liu Ming-Lei Tong National Time Center Chinese Academy of SciencesXi’an 710600China Key Laboratory of Time and Frequency Primary Standard Chinese Academy of SciencesXi’an 710600China University of Chinese Academy of Sciences Beijing 100049China

The detection of gravitational waves(GWs)by pulsar timing arrays(PTAs)is not only a very important supplementation of the verification of general relativity but also a new window to study the evolution of supermassive binary black holes and the early ***,so far the detection sensitivity of PTAs is not good enough to catch signals of GWs due to the disturbance of various *** this paper we explore the influences of the correlated noises caused by the reference clock errors and solar system ephemeris errors in pulsar timing on the detection of stochastic gravitational waves background(GWB).We demonstrate the power-law integrated sensitivity curves of GWB detection under the impacts from these correlated *** the simulated data,we find that the influence of different reference timescale is non-negligible,and the influence is even quite huge if one uses a very old version of solar system ***,the impact from these correlated noises on the sensitivity curve is very limited for the real observational data released by international pulsar timing arrays(IPTA).We also calculate the signalto-noise ratios based on the theoretical GW amplitude permitted by ***,we study how the detection sensitivity increases with more pulsar number and longer observation.

关键词： gravitational waves pulsars general time ephemerides

Phylogenetically clustering of rhizobia by genome structure:application to unclassified Rhizobium

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Journal of Environmental Sciences 2006年第3期18卷 530-536页

作者： ZHENG Jun-fang liu Gui-rong liu shu-lin Department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China Department of Microbiology Peking University Health Science Center Beijing 100083 China

Previous research reveals that the genome structures of rhizobial type strains and reference strains can reflect their phylogenetic relationships. In order to further explore the potential application of genome structure as a phylogenetic marker in rhizobial natural taxonomy, this study analyzed the genome structures of 29 unclassified nodule bacteria isolated from the root nodules of leguminous trees, Robinia sp., Dalbergia spp., and A lbizia spp. and 7 rhizobial reference strains by I-CeuI cleavage, then clustered these bacteria phylogenetically based on their genome structures and compared these clusters with those based on numerical taxonomy and 16S rDNA PCR-RFLP. Eleven phylogenetic clusters were obtained, The clusters were in large part consistent with those based on numerical taxonomy and 16S rDNA PCR-RFLP. Also there are inconsistent clusters based on the above three methods. But results are completely consistent with 16S rRNA clusters. This suggested that the genome structure clustering method can be used to lastly identify root nodule isolates and detect their phylogenetic relationships. The credibility and repeatability of the results, together with the simplicity and possibility to analyze a large number of strains in a short time of the method, indicates the broad potential application of genome structure as phylogenetic marker to categorize rhizobial isolates and should in the future facilitate biodiversity studies.

关键词： rhizobia genome structure phylogenetic analysis pulsed field gel electrophoresis I-CeuI

Tomato yellow leaf curl virus infection of tomato does not affect the performance of the Q and ZHJ2 biotypes of the viral vector Bemisia tabaci

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Insect Science 2011年第1期18卷 40-49页

作者： Meng Li Jian liu shu-Sheng liu Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects Institute of Insect Sciences Zhejiang UniversityHangzhou China

To better understand the etiology of begomovirus epidemics in regions under invasion we need to know how indigenous and invasive whitefly vectors respond to virus infection. We investigated both direct and indirect effects of infection with Tomato yellow leaf curl virus （TYLCV） on the performance of the invasive Q biotype and the indigenous Asian ZHJ2 biotype of whitefly Bemisia tabaci. The Q biotype performed better than the ZHJ2 biotype on either uninfected or virus-infected tomato plants. However, virus-infection of host plants did not, or only marginally affected, the performance of either biotype of whiteflies in terms of fecundity, longevity, survival, development and population increase. Likewise, association of the vectors with TYLCV did not affect fecundity and longevity of the Q or ZHJ2 biotypes on cotton, a non-host of TYLCV. These results indicate that the alien Q biotype whitefly, but not the indigenous ZHJ2 biotype, is likely to become the major vector of TYLCV in the field and facilitate virus epidemics.

关键词： Bemisia tabaci performance tomato Tomato yellow leaf curl virus virusinfection

Analysis of Safe Span Length and Fatigue Life of Submarine Pipelines

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China Ocean Engineering 2020年第1期34卷 119-130页

作者： HE Zhang-feng WEI Yuan liu shu-lin School of Mechatronic Engineering and Automation Shanghai University

Owing to the complex environmental conditions, suspension could induce complicated forces on submarine pipelines and even cause vortex-induced vibration, resulting in fatigue damage of pipelines. Through aiming at the 28-inch submarine pipeline in the East China Sea, the pipeline was segmented according to the similarity, considering the factors of pipe assembly, typhoon, current, wave and seabed topography. The effects of span length on natural frequency in each section of submarine pipeline were analyzed by finite element model. The maximum safe span length allowed by each pipeline section was verified by fatigue cumulative damage theory, and the fatigue life of each pipeline section were predicted. The results showed that each order natural frequency of the pipeline decreased with the increase of span length. The calculated results of empirical formulas were much smaller than those of the FEM analysis. The increase of the gap between the suspended pipeline and the seabed was beneficial to enhance the fatigue life of the suspended pipeline.

关键词： submarine pipeline safe span length fatigue life vortex-induced vibration

An RLC interconnect analyzable crosstalk model considering self-heating effect

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Chinese Physics B 2012年第2期21卷 552-560页

作者： Zhu Zhang-Ming liu shu-Bin School of Microelectronics Xidian UniversityXi'an 710071China

According to the thermal profile of actual multilevel interconnects, in this paper we propose a temperature distribution model of multilevel interconnects and derive an analytical crosstalk model for the distributed resistance inductance-capacitance （RLC） interconnect considering effect of thermal profile. According to the 65-nm complementary metal-oxide semiconductor （CMOS） process, we compare the proposed RLC analytical crosstalk model with the Hspice simulation results for different interconnect coupling conditions and the absolute error is within 6.5%. The computed results of the proposed analytical crosstalk model show that RCL crosstalk decreases with the increase of current density and increases with the increase of insulator thickness. This analytical crosstalk model can be applied to the electronic design automation （EDA） and the design optimization for nanometer CMOS integrated circuits.

关键词： multilevel interconnects temperature distribution RLC crosstalk

DYNAMIC RESPONSE ANALYSIS OF DDMS PLATFORM SUBJECTED TO ACTIONS OF WAVE GROUPS AND CURRENT FOURCES

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Journal of Hydrodynamics 2011年第6期23卷 697-708页

作者： SUN Zhao-chen WANG Xing-gang LIANG shu-xiu liu shu-Xue liu Si State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024China

Coupled dynamic analysis of the Deep Draft Multi-Spar （DDMS） platform and the mooring system under the action of waves and current is carried out in the time domain. Using a geometrically nonlinear finite element method, the mooring-line dynamics is simulated based on the total Lagrangian formulation. Wave groups are obtained by the JONSWAP spectrum and an empirical wave envelope spectrum involving two envelope-based factors Group Height Factor （GFH） and Group Length Factor （GLF）. The results show that the wave groups have a significant effect on the motion responses of the platform and the mooring line tensions.

关键词： Deep Draft Multi Spar (DDMS) platform dynamic response wave groups current fources