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The Convergence of Least-Squares Progressive Iterative Approximation for Singular Least-Squares Fitting System

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Journal of Systems Science & Complexity 2018年第6期31卷 1618-1632页

作者： LIN Hongwei cao qi ZHANG Xiaoting School of Mathematical Science State Key Laboratory of CAD&CG Zhejiang University

Data fitting is an extensively employed modeling tool in geometric design. With the advent of the big data era, the data sets to be fitted are made larger and larger, leading to more and more least-squares fitting systems with singular coefficient matrices. LSPIA (least-squares progressive iterative approximation) is an efficient iterative method for the least-squares fitting. However, the convergence of LSPIA for the singular least-squares fitting systems remains as an open problem. In this paper, the authors showed that LSPIA for the singular least-squares fitting systems is convergent. Moreover, in a special case, LSPIA converges to the Moore-Penrose (M-P) pseudo-inverse solution to the least- squares fitting result of the data set. This property makes LSPIA, an iterative method with clear geometric meanings, robust in geometric modeling applications. In addition, the authors discussed some implementation detail of LSPIA, and presented an example to validate the convergence of LSPIA for the singular least-squares fitting systems.

关键词： Data fitting geometric modeling LSPIA singular least-squares fitting system.

Robust control for constant thrust rendezvous under thrust failure

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Chinese Journal of Aeronautics 2015年第2期28卷 518-526页

作者： qi Yongqiang jia Yingmin Wang jian College of Sciences China University of Mining and Technology School of Automation Science and Electrical Engineering Beihang University School of Environment Science and Spatial Informatics China University of Mining and Technology

A robust constant thrust rendezvous approach under thrust failure is proposed based on the relative motion dynamic model. Firstly, the design problem is cast into a convex optimization problem by introducing a Lyapunov function subject to linear matrix inequalities. Secondly, the robust controllers satisfying the requirements can be designed by solving this optimization problem. Then, a new algorithm of constant thrust fitting is proposed through the impulse compensation and the fuel consumption under the theoretical continuous thrust and the actual constant thrust is cal- culated and compared by using the method proposed in this paper. Finally, the proposed method having the advantage of saving fuel is proved and the actual constant thrust switch control laws are obtained through the isochronous interpolation method, meanwhile, an illustrative example is pro- vided to show the effectiveness of the proposed control design method.

关键词： Constant thrust Optimal fuel Rendezvous Robust controller Thrust failure

Composite Configuration Interventional Therapy Robot for the Microwave Ablation of Liver Tumors

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Chinese Journal of Mechanical Engineering 2017年第6期30卷 1416-1425页

作者： Ying-Yu cao Long Xue Bo-Jin qi Li-Pei jiang Shuang-Cheng Deng Ping Liang jia Liu School of Mechanical Engineering and Automation Beihang University Opto-Mechatronic Equipment Technology Beijing Area Major Laboratory Beijing Institute of Petrochemical Technology Department of Interventional Ultrasound Chinese PLA General Hospital Thermotherapy Integrated Radiotherapy Department Hunan Cancer Hospital

The existing interventional therapy robots for the microwave ablation of liver tumors have a poor clinical applicability with a large volume, low positioning speed and complex automatic navigation control. To solve above problems, a composite configuration interventional therapy robot with passive and active joints is developed. The design of composite configuration reduces the size of the robot under the premise of a wide range of movement, and the robot with composite configuration can realizes rapid positioning with operation safety. The cumulative error of positioning is eliminated and the control complexity is reduced by decoupling active parts. The navigation algo- rithms for the robot are proposed based on solution of the inverse kinematics and geometric analysis. A simulation clinical test method is designed for the robot, and the functions of the robot and the navigation algorithms are verified by the test method. The mean error of navigation is 1.488 mm and the maximum error is 2.056 mm, and thepositioning time for the ablation needle is in 10 s. The experimental results show that the designed robot can meet the clinical requirements for the microwave ablation of liver tumors. The composite configuration is proposed in development of the interventional therapy robot for the microwave ablation of liver tumors, which provides a new idea for the structural design of medical robots.

关键词： Robot Composite configuration Interventional therapy Decoupling mechanismIntelligent positioning Composite configuration

Response of soil N_2O emissions to precipitation pulses under different nitrogen availabilities in a semiarid temperate steppe of Inner Mongolia, China

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Journal of Arid Land 2014年第4期6卷 410-422页

作者： XinChao LIU YuChun qi YunShe DONG qin PENG YaTing HE LiangJie SUN Junqiang jia CongCong cao Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of Chinese Academy of Sciences Institute of Agricultural Resources and Regional Planning Chinese Academy of Agriculture Sciences

Short-term nitrous oxide（N2O） pulse emissions caused by precipitation account for a considerable portion of the annual N2O emissions and are greatly influenced by soil nitrogen（N） dynamics. However, in Chinese semiarid temperate steppes, the response of N2O emissions to the coupling changes of precipitation and soil N availability is not yet fully understood. In this study, we conducted two 7-day field experiments in a semiarid temperate typical steppe of Inner Mongolia, China, to investigate the N2O emission pulses resulting from artificial precipitation events（approximately equivalent to 10.0 mm rainfall） under four N addition levels（0, 5, 10 and 20 g N/（m2·a）） using the static opaque chamber technique. The results show that the simulated rainfall during the dry period in 2010 caused greater short-term emission bursts than that during the relatively rainy observation period in 2011（P〈0.05）. No significant increase was observed for either the N2O peak effluxes or the weekly cumulative emissions（P〉0.05） with single water addition. The peak values of N2O efflux increased with the increasing N input. Only the treatments with water and medium（WN10） or high N addition（WN20） significantly increased the cumulative N2O emissions（P〈0.01） in both experimental periods. Under drought condition, the variations in soil N2O effluxes were positively correlated with the soil NH4-N concentrations in the three N input treatments（WN5, WN10, and WN20）. Besides, the soil moisture and temperature also greatly influenced the N2O pulse emissions, particularly the N2O pulse under the relatively rainy soil condition or in the treatments without N addition（ZN and ZWN）. The responses of the plant metabolism to the varying precipitation distribution and the length of drought period prior to rainfall could greatly affect the soil N dynamics and N2O emission pulses in semiarid grasslands.

关键词： temperate semiarid steppe nitrous oxide nitrogen availability precipitation

A meta-analysis of lamivudine for interruption of mother-to-child transmission of hepatitis B virus

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World Journal of Gastroenterology 2011年第38期17卷 4321-4333页

作者： Lei Han Hong-Wei Zhang jia-Xin Xie qi Zhang Hong-Yang Wang Guang- Wen cao Department of Epidemiology Second Military Medical University Shanghai 200433 China Laboratory for Signal Transduction the3rd Affiliated Hospital Second Military Medical UniversityShanghai 200433 China

AIM： To determine the therapeutic effect of lamivu- dine in late pregnancy for the interruption of motherto-child transmission （MTCT） of hepatitis B virus （HBV）. METHODS： Studies were identified by searching available databases up to January 2011. Inclusive criteria were HBV-carrier mothers who had been involved in randomized controlled clinical trials （RCTs） with lamivudine treatment in late pregnancy, and newborns or infants whose serum hepatitis B surface antigen （HBsAg）, hepatitis B e antigen （HBeAg） or HBV DNA had been documented. The relative risks （RRs） for inerruption of MTCT as indicated by HBsAg, HBV DNA or HBeAg of newborns or infants were calculated with 95% confidence interval （CI） to estimate the efficacy of lamivudine treatment. RESULTS： Fifteen RCTs including 1693 HBV-carrier mothers were included in this meta-analysis. The overall RR was 0.43 （95% CI, 0.25-0.76; 8 RCTs; Phet- erogeneity= 0.04） and 0.33 （95% CI, 0.23-0.47; 6 RCTs; Pheterogeneity = 0.93） indicated by newborn HBsAg or HBV DNA. The RR was 0.33 （95% CI, 0.21-0.50; 6 RCTs; Pheterogeneity = 0.46） and 0.32 （95% CI, 0.20-0.50; 4 RCTs; Pheterogeneity = 0.33） indicated by serum HBsAg or HBV DNA of infants 6-12 mo after birth. The RR （lamivudine vs hepatitis B immunoglobulin） was 0.27 （95% CI, 0.16-0.46; 5 RCTs; Pheterogeneity = 0.94） and 0.24 （95% CI, 0.07-0.79; 3 RCTs; Pheterogeneity = 0.60） indicated by newborn HBsAg or HBV DNA, respectively. In the mothers with viral load 〈 106 copies/mL after lamivudine treatment, the efficacy （RR, 95% CI） was 0.33, 0.21-0.53 （5 RCTs; Pheterogeneity = 0.82） for the interruption of MTCT, however, this value was not significant if maternal viral load was 〉 106 copies/mL after lamivudine treatment （P = 0.45, 2 RCTs）, as indicated by newborn serum HBsAg. The RR （lamivudine initiated from 28 wk of gestation vs control） was 0.34 （95% CI, 0.22-0.52; 7 RCTs; Pheterogeneity = 0.92） and 0.33 （95% CI, 0.22-0.50; 5 RCTs; Pheterogeneity = 0.86） indicated by newborn HBs

关键词： Hepatitis B virus Lamivudine Mother-to-child transmission Efficacy Meta-analysis

The differentiability of solutions for elliptic equations which degenerate on part of the boundary of a convex domain

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Applied Mathematics(A Journal of Chinese Universities) 2018年第4期33卷 421-435页

作者： SONG jia-xin cao Yi Department of Mathematics and Information Science Shaanxi Normal University

In this paper,we study the differentiability of solutions on the boundary for equartions of type L;u=;u/x;+|x|;;u/y;=f（x,y）,where λ is an arbitrary positive number. By introducing a proper metric that is related to the elliptic operator L;, we prove the differentiability on the boundary when some well-posed boundary conditions are satisfied. The main difficulty is the construction of new barrier functions in this article.

关键词： elliptic equations convex domain differentiability

Dielectric genetic tailoring strategy dominating MoSe_(2)@rGO assembled architecture with electromagnetic functions

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Journal of Advanced Ceramics 2024年第9期13卷 1461-1472页

作者： Wen-qiang cao qi Zheng Lin Li Chuan-Bao cao Mao-Sheng cao School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Key Laboratory for Photonic and Electronic Bandgap Materials Ministry of EducationSchool of Physics&Electron EngineeringHarbin Normal UniversityHarbin 150025China

The intensification of electromagnetic(EM)pollution and the development of military detection technology have increased the requirements for EM functional *** this study,a molybdenum diselenide@reduced graphene oxide(MoSe_(2)@rGO)-assembled architecture is constructed,where the MoSe_(2) nanosheets grow uniformly on the rGO *** regulating the contributions of conduction genes and polarization genes,adjustable EM functions of MoSe_(2)@rGO hybrids can be *** reflection loss(RL)of the sample can reach−68.7 dB at a thickness of 2.32 mm,and the maximum effective absorption bandwidth can reach 5.04 *** conduction genes dominate,the MoSe_(2)@rGO hybrids exhibit a 98.7%electromagnetic interference(EMI)shielding *** design of the EM energy conversion device and the results of the radar cross section(RCS)simulation demonstrate the practical application potential of the *** work provides inspiration for designing multifunctional EM materials.

关键词： MoSe_(2) graphene hybrids dielectric gene microwave absorption(MA) electromagnetic interference(EMI)shielding

Characterization of polyoxometalates by electrospray ionization mass spectrometry

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Science China Chemistry 2015年第7期58卷 1206-1210页

作者： qiaodi jia Yan Zhang Jie cao Key Laboratory of Cluster Science Ministry of Education of China Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials School of Chemistry Beijing Institute of Technology

The electrospray behaviors of saturated, substituted, and lacunary polyoxometalates （POMs） with classic Keggin and Dawson structures were investigated systematically by electrospray mass spectrometry （ESI-MS）. The anions included Keggin [SiW12O40]4-, [SiW11O39]8-, [SiW10O36]8 , [SiW9O34]10-, Dawson [P2W18O62]6-, [P2W17O61]10-, and metal-substituted Keggin derivatives such as [PW11MnO40]7-, [SiW10V2O40]6-, and [GeWgCu3O37]10-. Common species observed in the mass spectra arose from the protonation or cationization of either intact or dehydrated precursor ions. Compared to saturated and substituted POMs, lacunary POMs exhibited distinguished MS behaviors such as a much higher degree of cationization and dehydration of the bare polyoxoanions present in the mass spectra. In addition, some of these lacunary POMs were found to undergo subtle speciation change in solution. Freshly prepared solutions are suggested for synthetics for which lacunary POMs are starting materials. The advantages of the cation-exchange process which are prior to MS analysis are illustrated by an example.

关键词： saturated substituted and lacunary POMs electrospray ionization mass spectrometry cation-ion exchange process

Cascading failures in local-world evolving networks

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第10期9卷 1336-1340页

作者： Zhe-jing BAO Yi-jia cao School of Electrical Engineering Zhejiang University Hangzhou 310027 China College of Electrical and Information Engineering Hunan University Changsha 410082 China

The local-world (LW) evolving network model shows a transition for the degree distribution between the exponential and power-law distributions, depending on the LW size. Cascading failures under intentional attacks in LW network models with different LW sizes were investigated using the cascading failures load model. We found that the LW size has a significant impact on the network's robustness against deliberate attacks. It is much easier to trigger cascading failures in LW evolving networks with a larger LW size. Therefore, to avoid cascading failures in real networks with local preferential attachment such as the Internet, the World Trade Web and the multi-agent system, the LW size should be as small as possible.

关键词： Complex network Local world (LW) Cascading failures Power-law Attack