检索结果-南通市图书馆

Height and body mass index trajectories from 1975 to 2015 and prevalence of stunting,underweight and obesity in 2016 among children in Chinese cities:findings from five rounds of a national survey

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Pediatrics 2024年第4期20卷 404-412页

作者： Xin‑nan zong Hui Li Ya‑Qin Zhang Department of Growth and Development Capital Institute of PediatricsBeijing 100020China

Background A more comprehensive assessment of growth and nutrition in children is required in China due to rapid socioeconomic *** aimed to investigate height and body mass index(BMI)trajectories from 1975 to 2015 and the prevalence of stunting and obesity in 2016 among children in Chinese *** A total of 904,263 children from birth to 6.9 years were collected from a series of nationally representative surveys in *** and BMI trajectories and prevalence of stunting,underweight,overweight and obesity were *** The average height level of Chinese urban children under 7 years presented a positive secular trend from 1975 to 2015;however,a slowing tendency occurred in 2005‒*** apparent increase was observed at the 5th,50th and 95th percentiles of BMI in urban children aged 3 years and older,with a more prominent increase at the 95th *** total prevalence of stunting and underweight under 7 years was 1.4%and 2.0%,*** total prevalence of overweight and obesity under 7 years was 12.6%and 4.3%,respectively,with 12.7%and 4.9%for boys,12.6%and 3.6%for girls,12.1%and 4.0%in urban areas and 13.1%and 4.5%in suburban rural *** The average height level of Chinese urban children has reached World Health Organization child growth standards since 2005 and presented a slowing tendency in secular trend in 2005‒*** attention and efforts and public health interventions should be urgently made to combat overweight and obesity among preschool children.

关键词： Body mass index Children Height Obesity Stunting

Image Steganography by Pixel-Value Differencing Using General Quantization Ranges

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2024年第10期141卷 353-383页

作者： Da-Chun Wu zong-nan Shih Department of Computer and Communication Engineering National Kaohsiung University of Science and TechnologyKaohsiung824005TaiwanChina

A new steganographic method by pixel-value differencing(PVD)using general quantization ranges of pixel pairs’difference values is *** objective of this method is to provide a data embedding technique with a range table with range widths not limited to powers of 2,extending PVD-based methods to enhance their flexibility and data-embedding rates without changing their capabilities to resist security ***,the conventional PVD technique partitions a grayscale image into 1×2 non-overlapping *** entire range[0,255]of all possible absolute values of the pixel pairs’grayscale differences in the blocks is divided into multiple quantization *** width of each quantization range is a power of two to facilitate the direct embedding of the bit information with high embedding *** using power-of-two range widths,the embedding rates can drop using conventional embedding *** contrast,the proposed method uses general quantization range widths,and a multiple-based number conversion mechanism is employed skillfully to implement the use of nonpower-of-two range widths,with each pixel pair being employed to embed a digit in the multiple-based *** the message bits are converted into a big multiple-based number whose digits can be embedded into the pixel pairs with a higher embedding *** experimental results showed the feasibility of the proposed method and its resistance to security *** addition,implementation examples are provided,where the proposed method adopts non-power-of-two range widths and employsmultiple-based number conversion to expand the data-hiding and steganalysis-resisting capabilities of other PVD methods.

关键词： Steganography pixel-value differencing multiple-based number conversion general quantization range

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

基于双焦透镜的双踪远场自动准直

中国激光 2024年第6期51卷 94-99页

作者：宗楠唐顺兴郭亚晶中国科学院上海光学精密机械研究所高功率激光物理联合实验室上海201800 上海交通大学 IFSA协同创新中心上海200240

在光束传输控制中,反馈系统需要具有较高的角度分辨率,以达到自动准直的精度要求,此外还需要具备一定的角视场,以降低对初始安装和调试的精度要求。提出了一种基于双焦透镜的双踪远场自动准直方案,在同一光学系统中实现了高精度和大视... 详细信息

在光束传输控制中,反馈系统需要具有较高的角度分辨率,以达到自动准直的精度要求,此外还需要具备一定的角视场,以降低对初始安装和调试的精度要求。提出了一种基于双焦透镜的双踪远场自动准直方案,在同一光学系统中实现了高精度和大视场两种角度分辨率的远场图像反馈系统。基于矩阵光学理论对远场图像反馈系统进行数值分析,给出了双焦透镜的等效传输矩阵,并分析了双焦透镜的角度分辨率和视场特性。设计并开展实验对基于双焦透镜的双踪远场自动准直方案进行了性能演示,实验结果表明,高精度下的角度分辨率约为大视场下角度分辨率的6.9倍,与设计值(6.6倍)基本相符。

关键词：光学设计高功率激光自动准直远场成像矩阵光学

Comparison of updated birth weight,length and head circumference charts by gestational age in China with the INTERGROWTH-21 st NCSS charts:a population-based study

在线全文

学校读者我要写书评

暂无评论

World Journal of Pediatrics 2023年第1期19卷 96-105页

作者： Ya-Qin Zhang Hui Li Xin-nan zong Hua-Hong Wu Department of Growth and Development Capital Institute of PediatricsNo.2Ya Bao RoadChaoyang DistrictBeijingChina

Background INTERGROWTH-21 st Newborn Cross-Sectional Study(NCSS)charts were established and recommended for global ***,whether one international reference is appropriate for all populations is still *** aim to compare the updated Chinese birth size charts by gestational age with INTERGROWTH-21st NCSS *** A cross-sectional survey was carried out,and the birth weight,length and head circumference of 24,375 infants born after uncomplicated pregnancies at gestational age ranging from 24+0 to 42+6 weeks were measured in 13 cities in China from 2015 to *** charts were *** measurements of all these infants were evaluated by the methods of calculating their Z scores using the INTERGROWTH-21 st *** prevalence of small for gestational age(SGA)and large for gestational age(LGA)based on birth weight was analyzed using Chinese charts and INTERGROWTH-21st *** The mean Z scores were 0.10 for birth weight,0.35 for length and-0.02 for head *** to the INTERGROWTH-21st charts,the Chinese birth weight percentile curves were higher except for the 90th percentile at 29-37 weeks gestational age,and the length percentile curves were higher after 33 weeks gestational age,while the 10th percentile of the head circumference was lower and the other percentiles were *** prevalence of SGA was 10.1%[95%confidence interval(CI)=9.7%-10.5%]using the Chinese birth weight chart and 6.5%(95%CI=6.2%-6.8%)using the INTERGROWTH-21 st birth weight *** prevalence of LGA was 9.9%(95%CI=9.5%-10.2%)and 8.2%(95%CI=7.9%-8.6%)using the Chinese and INTERGROWTH-21st birth weight charts,*** Chinese birth size charts based on infants born after uncomplicated pregnancies were different from the INTER-GROWTH-21st *** in the classification of newborns by the two charts should receive attention,and whether the application of INTERGROWTH-21st in Chinese newborns will lead to miscl

关键词： Birth length Birth weight Growth charts Head circumference Newborns

Changes of feeding patterns in Chinese city children under 2 years from 1985 to 2015: results from a series of national cross-sectional surveys

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Pediatrics 2019年第2期15卷 176-181页

作者： Hua-Hong Wu Ya-Qin Zhang Xin-nan zong Hui Li Department of Growth and Development Capital Institute of PediatricsYaBao RoadChaoYang DistrictBeijing 100020China

Background In China,as the social transformation and economic development from 1985 to 2015,children's feeding pattern has undergone some *** we aimed to analyze the secular trend on feeding patterns of city children in *** All data were from a series of national survey which implemented once every 10 years in China from 1985 to *** use same indexes to evaluate the feeding pattern of children in these four *** From 1985 to 2005,the exclusive breastfeeding rates in infants under 6 months of age decreased,especially in suburban areas decreased by 17.7%;the continuous breastfeeding rate of 1-year-old children in suburban area decreased from 60.1 to 27.6%.However,from 2005 to 2015,the exclusive breastfeeding rates under 6 months of age increased by 16.0% in urban areas and 5.9% in suburban areas;the continuous breastfeeding rate of 1-year-old children in urban increased from 17.0 to 36.0%.The overall feeding rate of complementary food in infants under 6 months of age declined from 1985 to 2015;the average age at introduction of all complementary foods was around 6 months of age in *** There is an obvious trend on feeding pattern of Chinese *** 1985 to 2005,the breastfeeding rate decreased,the duration time of breastfeeding was shortened and the age at introduction of complementary food was *** 2005 to 2015,the breastfeeding rate increased,the duration time of breastfeeding was prolonged,and the age at introduction of complementary food was postponed.

关键词： Breastfeeding Complementary feeding Infant and young children Secular change

A Consistent Characteristic Boundary Condition for General Fluid Mixture and Its Implementation in a Preconditioning Scheme

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Applied Mathematics and Mechanics 2012年第1期4卷 72-92页

作者： Hua-Guang Li nan zong Xi-Yun Lu Vigor Yang Department of Modern Mechanics The University of Science and Technology of ChinaHefeiAnhui 230026China Department of Mechanical and Nuclear Engineering The Pennsylvania State UniversityUniversity ParkPA 16802USA School of Aerospace Engineering The Georgia Institute of TechnologyAtlantaGA 30332USA

Characteristic boundary conditions that are capable of handling general fluid mixtures flow at all flow speeds are *** formulation is based on fundamental thermodynamics theories incorporated into an efficient preconditioning scheme in a unified *** one-dimensional inviscid(LODI)relations compatible to the preconditioning system are proposed to obtain information carried by incoming characteristic waves at boundaries *** approach has been validated against a variety of sample problems at a broad range of fluid states and flow *** acoustic waves and hydrodynamic flow features can pass through the boundaries of computational domain transparently without any unphysical reflection or spurious *** approach can be reliably applied to fluid flows at extensive thermodynamic states and flow speeds in numerical ***,the use of the boundary condition shows to improve the computational efficiency.

关键词： Real-fluid preconditioning method method of characteristics LODI relations

A 37 mJ,100 Hz,high energy single frequency oscillator

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 Physics B 2021年第8期30卷 392-397页

作者： Yu Shen Yong Bo nan zong Shenjin Zhang Qinjun Peng Zuyan Xu Research Center for Laser Physics and Technology Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China Key Laboratory of Solid State Laser Key Laboratory of Function Crystal and Laser TechnologyChinese Academy of SciencesBeijing 100190China

Ways on energy enhancement for single frequency oscillator are reported in this *** quantitative analysis on gain and loss coefficients for each cavity mode with inserted etalons,a 37 mJ,100 Hz high energy single-frequency Nd:YAG oscillator is *** pulse energy is promoted by enhancement of nearly 7 times for a single frequency oscillator *** result proves that this method does help for energy *** has attractive potential for high energy single frequency oscillator design,especially on condition of intensive side pumped or long cavity laser,where strong competitors exist and are hard to be suppressed.

关键词： Nd:YAG laser high pulse energy single frequency oscillator

Pump pulse characteristics of quasi-continuous-wave diode-side-pumped Nd:YAG laser

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第5期31卷 355-359页

作者： Zexin Song Qi Bian Yu Shen Keling Gong nan zong Qingshuang zong Yong Bo Qinjun Peng Key Laboratory of Solid State Laser Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China Key Laboratory of Function Crystal and Laser Technology Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100190China Southwest Institute of Technical Physics Chengdu 610041China

The influence of pumping laser pulse on the property of quasi-continuous-wave(QCW)diode-side-pumped Nd:YAG laser is investigated theoretically and *** remaining a fixed duty cycle,the average output power increases,and the corresponding thermal focal length shorten with the increase of the pump pulse duration,which attributes to the decrease of the ratio of pulse buildup time to the pulse *** a pump power of 146 W,the laser output power changes from 65.1 W to 81.2 W when the pulse duration is adjusted from 150μs to 1000μs,confirming a significant enhancement of 24.7%.A laser rate equation model incorporating the amplified spontaneous emission is also utilized and numerically solved,and the simulated results agree well with the experimental data.

关键词： pump pulse duration diode-side-pumped pulsed Nd:YAG laser laser rate equation amplified spontaneous emission

A review on the multi-scaled structures and mechanical/thermal properties of tool steels fabricated by laser powder bed fusion additive manufacturing

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 1048-1071页

作者： Huajing zong nan Kang Zehao Qin Mohamed El Mansori Arts et Metiers Institute of Technology MSMPHESAM UniversitéChâlons-en-Champagne F-51006France Texas A&M Engineering Experiment Station Institute for Manufacturing SystemsCollege Station TX77843USA

The laser powder bed fusion(LPBF) process can integrally form geometrically complex and high-performance metallic parts that have attracted much interest,especially in the molds *** appearance of the LPBF makes it possible to design and produce complex conformal cooling channel systems in ***,LPBF-processed tool steels have attracted more and more *** complex thermal history in the LPBF process makes the microstructural characteristics and properties different from those of conventional manufactured tool *** paper provides an overview of LPBF-processed tool steels by describing the physical phenomena,the microstructural characteristics,and the mechanical/thermal properties,including tensile properties,wear resistance,and thermal *** microstructural characteristics are presented through a multiscale perspective,ranging from densification,meso-structure,microstructure,substructure in grains,to ***,a summary of tool steels and their challenges and outlooks are introduced.

关键词： additive manufacturing laser powder bed fusion tool steel multi-scaled structure mechanical properties thermal properties