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Landweber Iterative Methods for Angle-limited Image Reconstruction

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Acta Mathematicae Applicatae Sinica 2009年第2期25卷 327-334页

作者： gang-rong qu Ming Jiang School of Science Beijing Jiaotong University Beijing 100044 China LMAM School of Mathematical Sciences Peking University Beijing 100871 China

We introduce a general iterative scheme for angle-limited image reconstruction based on Landwebet＇s method. We derive a representation formula for this scheme and consequently establish its convergence conditions. Our results suggest certain relaxation strategies for an accelerated convergence for angle-limited image reconstruction in L^2-norm comparing with alternative projection methods. The convolution-backprojection algorithm is given for this iterative process.

关键词： The Landweber iteration angle-limited image reconstruction the selections of relaxation coefficients convolution-backprojection algorithm

An Iterative Algorithm for Angle-limited Three-dimensional Image Reconstruction

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Acta Mathematicae Applicatae Sinica 2008年第1期24卷 157-166页

作者： gang-rong qu Yong-sheng Lan Ming Jiang School of Science Beijing Jiaotong University Beijing 100044 China School of Mathematical Sciences Peking University Beijing 100871 China

We establish an improved GP iterative algorithm for the extrapolation of band-limited function to fully 3-dimensional image reconstruction by the convolution-backprojection algorithm. Numerical experiments demonstrate... 详细信息

关键词： Fully 3-dimensional image reconstruction convolution-back projection algorithm angle-limited image reconstruction

Convergence Results of Landweber Iterations for Linear Systems

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Acta Mathematicae Applicatae Sinica 2014年第1期30卷 111-118页

作者： gang-rong qu Ming JIANG Yuan-jian YANG School of Science Beijing Jiaotong University Beijing Center for Mathematics and Information Interdisciplinary Sciences LMAM School of Mathematical SciencesPeking University

The Landweber scheme is a method for algebraic image reconstructions. The convergence behavior of the Landweber scheme is of both theoretical and practical importance. Using the diagonalization of matrix, we derive a neat iterative representation formula for the Landweber schemes and consequently establish the convergence conditions of Landweber iteration. This work refines our previous convergence results on the Landweber scheme.

关键词： algebraic image reconstruction Landweber scheme weighted least-squares convergence conditions

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玛欣凯维奇函数与泊松核的一个新微分性质

数学学报（中文版） 2016年第1期59卷 1-10页

作者：汪成咏渠刚荣北京交通大学数学系北京100044

将Stein[On the functions of Littlewood-Paley,Lusin,and Marcinkiewicz,***.,1958,88:430-466]中的玛欣凯维奇函数的逆向不等式推广到一般情形.主要结果是对于n-维欧几里得空间k-阶球面调和函数空间的任意一基底,得到玛欣凯维奇函数的一般性的逆向不等式,即存在不依赖于函数f正常数C_p,使得||f||_p≤C_pΣ_(j=1)~N=1||μ_j(f)||_p,其中{μ_j(f)}_(j=1)~N是f的由这些球面调和函数生成的玛欣凯维奇函数.此外,对于任意的n-变元的k-阶调和多项式Q(x)以及泊松核P_t(x),有Q(D)P_t(x)=C_n k(tQ(x))/((|x|)~2+t^2^(n+2k+1)/2).

关键词：玛欣凯维奇函数泊松核向量值奇异积分算子

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向量值哈代-洛伦茨空间

数学学报（中文版） 2016年第4期59卷 489-504页

作者：汪成咏渠刚荣北京交通大学数学系北京100044

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关键词：哈代-洛伦茨空间极大函数泊松积分缓分布

PRICE AND SERVICE COMPETITION WITH MAINTENANCE SERVICE BUNDLING

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Journal of Systems Science and Systems Engineering 2015年第2期24卷 168-189页

作者： Yi Wang Linyan Sun rong qu gang Li Department of Industrial Engineering School of ManagementHangzhou Dianzi University Department of Industrial Engineering School of ManagementXi'an Jiaotong University Automated Scheduling Optimization and Planning Group School of Computer ScienceUniversity of Nottingham

In many equipment manufacturing industries, firms compete with each other not only on products price, but also on maintenance service. More and more traditional products oriented finns are offering their customers products bundled with maintenance service （P＆S bundles）. In this study, we examine finns＇ incentive to offer customers products bundling with long-term maintenance or repair support service in a duopoly competitive environment. When providing P＆S bundles, a finn need to determine the service level （in terms of average response time guarantee for the service in this paper） to offer and needs to build a service facility to handle the maintenance service requirements. Based on the analysis of three sub-game models, we characterize the market conditions in which only one firm, both finns or neither finn will offer P＆S bundles. Finally, we analyze the affects of serval market factors on firms＇ strategy choices.

关键词： Service competition queues products and service bundles product differentiation

Unraveling brain aging through the lens of oral microbiota

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Neural Regeneration Research 2025年第7期20卷 1930-1943页

作者： Qinchao Hu Si Wang Weiqi Zhang Jing qu Guang-Hui Liu State Key Laboratory of Membrane Biology Institute of ZoologyChinese Academy of SciencesBeijingChina Hospital of Stomatology Guanghua School of StomatologyGuangdong Provincial Key Laboratory of StomatologySun Yat-sen UniversityGuangzhouGuangdong ProvinceChina Advanced Innovation Center for Human Brain Protection and National Clinical Research Center for Geriatric Disorders Xuanwu HospitalCapital Medical UniversityBeijingChina Aging Translational Medicine Center International Center for Aging and CancerBeijing Municipal Geriatric Medical Research CenterXuanwu HospitalCapital Medical UniversityBeijingChina CAS Key Laboratory of Genomic and Precision Medicine Beijing Institute of GenomicsChinese Academy of Sciences and China National Center for BioinformationBeijingChina University of Chinese Academy of Sciences BeijingChina Institute for Stem Cell and Regeneration Chinese Academy of SciencesBeijingChina Aging Biomarker Consortium BeijingChina State Key Laboratory of Stem Cell and Reproductive Biology Institute of ZoologyChinese Academy of SciencesBeijingChina Beijing Institute for Stem Cell and Regenerative Medicine BeijingChina

The oral cavity is a complex physiological community encompassing a wide range of *** of oral microbiota can lead to various oral infectious diseases,such as periodontitis and tooth decay,and even affect systemic health,including brain aging and neurodegenerative *** studies have highlighted how oral microbes might be involved in brain aging and neurodegeneration,indicating potential avenues for intervention *** this review,we summarize clinical evidence demonstrating a link between oral microbes/oral infectious diseases and brain aging/neurodegenerative diseases,and dissect potential mechanisms by which oral microbes contribute to brain aging and *** also highlight advances in therapeutic development grounded in the realm of oral microbes,with the goal of advancing brain health and promoting healthy aging.

关键词： Alzheimer's disease brain aging multiple sclerosis neurodegeneration neurodegenerative diseases oral microbiota Parkinson's disease periodontitis bacteria Porphyromonas gingivalis

A Modified qu EChERS-DART-MS/MS Technique for High-Throughput Detection of Organophosphate Nerve Agent Hydrolysis Products in Environmental Samples

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Journal of Analysis and Testing 2023年第2期7卷 163-171页

作者： gang qu Bo Chen Shilei Liu Qiaoli Zhang Yang Yang Qingshan Fu College of Material Science and Engineering Sichuan University of Science and EngineeringZigong 643000China State Key Laboratory of NBC Protection for Civilian Beijing 102205China Laboratory of Analytical Chemistry Research Institute of Chemical DefenceBeijing 102205China

Organophosphate nerve agents(OPNAs)are lethal chemical weapons(CWs)which hydrolyze rapidly to alkyl phosphate compounds in the *** identification of alkyl phosphate compounds in the environment is critical for the verification of ***,due to the complex sample preparation and long detection process for organophosphate nerve agent hydrolysis products(OPNAHPs),their high-throughput determination is *** simplify sample preparation and detection of OPNAHPs from environmental samples,a quick,easy,cheap,effective,rugged and safe(qu ECh ERS)method for the simultaneous purification of the five OPNAHPs in environmental samples combined with detection through direct analysis in real-time ionization source coupled with tandem mass spectrometer(DART-MS/MS)was *** internal standard method was applied for the *** method exhibited a good linearity(R^(2)>0.991)in the range of 1.00 ng/m L-4.00μg/m *** limits of detection and limits of quantification were 1.00-7.00 ng/m L and 10.0-20.0 ng/m L,*** recoveries of OPNAHPs in environmental samples were between 65.3%and 107%,with relative standard deviations ranged from 1.6%to 19%.In addition,the sample preparation and analysis process for OPNAHPs could be completed in less than 10 *** results demonstrated that the modified qu ECh ERS method could quickly and efficiently remove the matrix of environmental *** with DART-MS/MS,an accurate and high-throughput detection method of OPNAHPs in environmental samples was *** developed method has great potential in the fields of early warning,clinical treatment and environmental decontamination.

关键词： OPNAHPs quEChERS DART-MS/MS Environmental samples

Dynamic Regulation of Hydrogen Bonding Networks and Solvation Structures for Synergistic Solar‑Thermal Desalination of Seawater and Catalytic Degradation of Organic Pollutants

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Nano-Micro Letters 2025年第2期17卷 548-565页

作者： Ming‑Yuan Yu Jing Wu Guang Yin Fan‑Zhen Jiao Zhong‑Zhen Yu Jin qu Beijing Key Laboratory of Advanced Functional Polymer Composites Beijing University of Chemical TechnologyBeijing 100029People’s Republic of China State Key Laboratory of Organic‑Inorganic Composites College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029People’s Republic of China

Although solar steam generation strategy is efficient in desalinating seawater,it is still challenging to achieve continuous solar-thermal desalination of seawater and catalytic degradation of organic ***,dynamic regulations of hydrogen bonding networks and solvation structures are realized by designing an asymmetric bilayer membrane consisting of a bacterial cellulose/carbon nanotube/Co_(2)(OH)_(2)CO_(3)nanorod top layer and a bacterial cellulose/Co_(2)(OH)_(2)CO_(3)nanorod(BCH)bottom ***,the hydrogen bonding networks inside the membrane can be tuned by the rich surface–OH groups of the bacterial cellulose and Co_(2)(OH)_(2)CO_(3)as well as the ions and radicals in situ generated during the catalysis ***,both SO_(4)^(2−)and HSO_(5)−can regulate the solvation structure of Na^(+)and be adsorbed more preferentially on the evaporation surface than Cl^(−),thus hindering the de-solvation of the solvated Na^(+)and subsequent nucleation/growth of ***,the heat generated by the solar-thermal energy conversion can accelerate the reaction kinetics and enhance the catalytic degradation *** work provides a flow-bed water purification system with an asymmetric solar-thermal and catalytic membrane for synergistic solar thermal desalination of seawater/brine and catalytic degradation of organic pollutants.

关键词： Solar steam generation Seawater desalination Catalytic degradation Bacterial cellulose Cobalt hydroxycarbonate nanorods