检索结果-南通市图书馆

顾及地理环境各向异性的PM_(2.5)浓度时空预测模型

在线全文

学校读者我要写书评

暂无评论

地球信息科学学报 2024年第9期26卷 2106-2122页

作者：王军杰王达丁晨唐建波石岩杨学习中南大学地理信息系长沙410083 湖南省地理空间信息工程技术研究中心长沙410018

PM_(2.5)浓度预测对于空气污染的防控和治理具有重要意义。传统图卷积神经网络(Graph Convolutional Network,GCN)等时空预测模型主要通过监测站点间的欧氏距离来度量PM_(2.5)分布的空间相关性,未顾及地形和风向等因素对大气污染物传输... 详细信息

PM_(2.5)浓度预测对于空气污染的防控和治理具有重要意义。传统图卷积神经网络(Graph Convolutional Network,GCN)等时空预测模型主要通过监测站点间的欧氏距离来度量PM_(2.5)分布的空间相关性,未顾及地形和风向等因素对大气污染物传输过程的各向异性影响,导致地形复杂区域内的预测结果精度偏低。为此,本文提出了一种顾及地理环境各向异性的PM_(2.5)浓度时空图卷积网络预测模型。首先,考虑地理环境的各向异性特征,利用地形和风向等对站点间PM_(2.5)传播的各向异性影响构建GCN的边,将站点PM_(2.5)浓度、土地利用和其他气象因子建模为GCN的节点特征。其次,通过GCN提取站点PM_(2.5)浓度的空间特征。最后,通过门控循环单元(Gate Recurrent Unit,GRU)建模站点PM_(2.5)浓度的时间特征并进行预测。本文以山地型省份贵州省2017年逐小时PM_(2.5)浓度记录进行实验,并采用一系列时空预测基线模型(GTWR、STSVR和GCN+GRU)与本文模型进行对比。实验结果表明:①本文模型的PM_(2.5)浓度预测结果的RMSE、MAE别为10.047、6.848,相比基线模型平均下降了11.29%和12.16%;R2为0.883,比基线平均提升了3.72%;②通过不同地形对站点PM_(2.5)浓度相关性影响分析,论证了山脉沟谷等地形会显著影响站点间的PM_(2.5)浓度的相关性,进而影响站点PM_(2.5)浓度预测结果;③充分考虑地形和风向对PM_(2.5)传播产生的各向异性影响,能够显著提升存在山脉和沟谷地形区域内PM_(2.5)预测精度。

关键词： PM_(2.5)浓度预测时空图卷积网络空间相关性地理协变量地形距离风向各向异性地理环境特征

A reconstructed edge-based smoothed DSG element based on global coordinates for analysis of Reissner–Mindlin plates

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2017年第1期33卷 83-105页

作者： gang Yang De’an Hu Shuyao Long State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha 410082China

A reconstructed edge-based smoothed triangular element, which is incorporated with the discrete shear gap (DSG) method, is formulated based on the global coordinate for analysis of Reissner-Mindlin plates. A symbolic integration combined with the smoothing technique is implemented to calculate the smoothed finite element matrices, which is integrated along the boundaries of each smoothing cell. Numerical results show that the proposed element is free from shear locking, and its results are in good agreement with the exact solutions, even for very thin plates with extremely distorted elements. The proposed element gives more accurate results than the original DSG element without smoothing, and it can be taken as an alternative element for analysis of Reissner-Mindlin plates. The prominent feature of the present element is that the integration scheme is unified in the smoothed form for all of the finite element matrices.

关键词： Reissner-Mindlin plate DSG method Symbolic integration Smoothing technique Global coordinate Distorted element

Prevalence of Dyslipidemia among Patients Received at the Biochemistry Unit of the Charles de Gaulle Pediatric University Hospital in Ouagadougou

在线全文

学校读者我要写书评

暂无评论

Advances in Biological Chemistry 2024年第1期14卷 16-26页

作者： Fabienne Marie Soudre Arnaud Kouraogo Alice Kiba Ollo da Mahutin Benoîte Hounhoui Diema Nadia Karama Seraphine Mano Denis Claude Drabo Augustin Kyetega Raoul Karfo Elie Kabre Jean Sakande Health Sciences Training and Research Unit Joseph Ki-Zerbo University Ouagadougou Burkina Faso Charles de Gaulle Pediatric University Hospital Ouagadougou Burkina Faso Health Sciences Institute Nazi BONI University Bobo Dioulasso Burkina Faso Biochemistry Unit Sourou Sanou University Hospital Bobo Dioulasso Burkina Faso Tengandogo University Hospital Ouagadougou Burkina Faso Faculty of Health Sciences Saint Thomas d’Aquin University Ouagadougou Burkina Faso Yalgado Ouedraogo University Hospital Ouagadougou Burkina Faso National Agency for Environmental Food Labor and Health Product Safety Ouagadougou Burkina Faso

Introduction: Cardiovascular disease represents a major public health burden worldwide. Research and management of risk factors contribute to the prevention of these diseases. The aim of this study was to assess the prevalence of dyslipidemia in the biochemistry unit of the Charles De Gaulle Pediatric University Hospital (CHUP-CDG) in Ouagadougou. Material and Methods: This was a descriptive and analytical cross-sectional study, with retrospective data collection from January 1, 2020 to December 31, 2022. Patients of all ages who performed a lipid panel in the CHUP-CDG biochemistry unit during the study period have been included. Results: A total of 2872 patients have been included. The mean age of the study population was 27.72 ± 19.51 years and the M/F sex ratio was 0.81. Among the patients, 22.84% had at least one dyslipidemia. The prevalences of hypercholesterolemia, hypo-HDL cholesterolemia and hyper-LDL cholesterolemia were 11.57%, 49.19% and 57.50% respectively. Hypertriglyceridemia and mixed hyperlipidemia were present in 9.04% and 2.08% of patients. Hypercholesterolemia was significantly more frequent in the female sex (p = 0.0077);hyper-LDL cholesterolemia (p = 0.0255) and mixed hyperlipidemia (p Conclusion: The relatively high prevalence of dyslipidemia in the study indicates a worrying situation. It would therefore appear essential to extend the search for risk factors nationwide, particularly those that can be modified, in order to reduce morbidity and mortality linked to cardiovascular disease.

关键词： Dyslipidemia Lipid Profile Lipid Abnormalities Prevalence Burkina Faso

Torsion Fields Generated by the Quantum Effects of Macro-bodies

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第12期22卷 335-343页

作者： da-Ming Chen National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

We generalize Einstein's General Relativity(GR)by assuming that all matter(including macro-objects)has quantum *** appropriate theory to fulfill this task is Gauge Theory Gravity(GTG)developed by the Cambridge *** is a“spin-torsion”theory,according to which,gravitational effects are described by a pair of gauge fields defined over a flat Minkowski background *** matter content is completely described by the Dirac spinor field,and the quantum effects of matter are identified as the spin tensor derived from the spinor *** existence of the spin of matter results in the torsion field defined over *** field plays the role of Bohmian quantum potential which turns out to be a kind of repulsive force as opposed to the gravitational potential which is *** equivalence principle remains and essential in this theory so that GR is relegated to a locally approximate theory wherein the quantum effects(torsion)are *** a toy model,we assume that the macro matter content can be described by the covariant Dirac equation and apply this theory to the simplest radially symmetric and static gravitational ***,by virtue of the cosmological principle,we are led to a static universe model in which the Hubble redshifts arise from the torsion fields.

关键词： cosmology:theory (cosmology:)dark matter (cosmology:)dark energy

Analysis of the Y(4220)and Y(4390)as molecular states with QCD sum rules

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2017年第8期41卷 31-38页

作者： Zhi-gang Wang Department of Physics North China Electric Power University Baoding 071003 China

In this article, we assign the Y（4390） and Y（4220） to be the vector molecular states D1（2420） and D＊ ＊0（2400）, respectively, and study their masses and pole residues in detail with the QCD sum rules. The... 详细信息

关键词： molecular states QCD sum rules

Selected-Mapping Peak-to-Average Power Reduction Method with Orthogonal Pilot Sequences in Underwater Acoustic OFDM System Without Side Information

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2021年第1期30卷 160-163页

作者： QIAO gang XING Siyu ZHOU Feng Acoustic Science and Technology Laboratory Harbin Engineering University Key Laboratory of Marine Information Acquisition and Security (Harbin Engineering University) Ministry of Industry and Information Technology College of Underwater Acoustic Engineering Harbin Engineering University

A novel Selected-mapping(SLM) Peak-to-average power ratio(PAPR) reduction scheme requires no Side information(SI) in Underwater acoustic(UWA)OFDM system is proposed. In the proposed scheme,every distinct phase sequence is represented by a unique Orthogonal comb pilot sequence(OPS), and the orthogonal properties of the OPSs are used to distinguish the index of phase sequences at the receiver. Therefore, the proposed scheme does not need to reserve bits for transmitting SI,so that the data rate can be raised. Simulation results show that the PAPR reduction performance has almost 0.5 d B gains comparing to the Conventional SLM(C-SLM)scheme and the Bit error ratio(BER) performance is approximately the same as the SLM scheme with perfect SI. Field experimental results also demonstrate that the proposed scheme can differentiate phase sequences,therefore significantly enhance the quality of the UWA OFDM communication system.

关键词： Modulation and coding methods Communication channel equalisation and identification Acoustic and other telecommunication systems and equipment Error statistics (inc. error probability) Underwater acoustic communication OFDM PAPR reduction Selected mapping

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

绝经后初发系统性红斑狼疮患者的临床分析

重庆医学 2024年第10期53卷 1512-1518页

作者：汝露达展云南通大学附属医院风湿免疫科江苏南通226001

目的探讨绝经后初发系统性红斑狼疮(SLE)患者的临床特点。方法回顾性分析2015年1月至2021年3月该院住院治疗且首次发病的289例SLE患者病例资料,以女性患者发病时是否绝经分为绝经组(n=56)和育龄组(n=205),将男性患者作为男性组(n=28)。... 详细信息

目的探讨绝经后初发系统性红斑狼疮(SLE)患者的临床特点。方法回顾性分析2015年1月至2021年3月该院住院治疗且首次发病的289例SLE患者病例资料,以女性患者发病时是否绝经分为绝经组(n=56)和育龄组(n=205),将男性患者作为男性组(n=28)。分析比较3组一般资料、首发症状、临床表现、实验室指标、SLE疾病活动指数(SLEdaI)的差异。结果绝经组发病年龄40~daI评分和SLEdaI评分>20分患者比例更低(PdaI评分较低。

关键词：系统性红斑狼疮绝经后发病临床特点器官损害疾病活动度

INCREASED SPHERULITIC GROWTH RATES OF SEMICRYSTALLINE POLYMER DUE TO ENHANCED LIMITED LOCAL CHAIN SEGMENTAL MOBILITY AT THE INTERFACE OF DOUBLE-LAYER THIN FILMS

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2013年第9期31卷 1276-1283页

作者： Ya-qiong Zhang Zhi-gang Wang CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and Engineering Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China

In this work the nucleation and growth of spherulites for the below polylactide （PLA） layer in poly（ε- caprolactone）/polylactide （PCL/PLA） double-layer films during isothermal crystallization at various temperatures above the melting point of PCL have been investigated by using polarized optical microscopy （POM）. It is revealed that two types of spherulitic morphologies are observed in PCL/PLA double-layer films. One is the well defined highly birefringent spherulites, and the other one is the coarse spherulites. It is interesting to find that the spherulitic growth rate of the coarse spherulites is higher than that of the well defined spherulites. It is thought that the coarse spherulites nucleate and grow with the assistance of the interfaces between the PCL and PLA layers, and the well defined highly birefringent spherulites only nucleate and grow in the PLA layer.

关键词： Polylactide Poly(ε-caprolactone) Interface Crystallization Spherulite.

信息基础设施建设、养殖主体分化与生猪价格波动——基于多期双重差分模型的分析

在线全文

学校读者我要写书评

暂无评论

价格月刊 2024年第7期 9-17页

作者：王刚毅桂雪梅李春雷东北农业大学经济管理学院黑龙江哈尔滨150030

长期以来,中国生猪价格呈现出周期性波动的显著特征。然而,信息对生猪价格波动产生的具体影响尚待深入探究。基于2011—2018年的省级面板数据,借助“宽带中国”战略这一自然实验设定,实证检验了信息基础设施建设对生猪价格波动的影响及... 详细信息

长期以来,中国生猪价格呈现出周期性波动的显著特征。然而,信息对生猪价格波动产生的具体影响尚待深入探究。基于2011—2018年的省级面板数据,借助“宽带中国”战略这一自然实验设定,实证检验了信息基础设施建设对生猪价格波动的影响及作用机制。研究结果显示,信息基础设施建设是生猪价格波动的重要影响因素之一。随着信息基础设施建设水平的提升,养殖户对生猪价格的反应敏感性增强,且信息基础设施建设对生猪价格波动的影响呈现出加速的非线性特征。进一步的调节效应分析显示,养殖主体的分化现象加剧了信息基础设施建设对生猪价格波动的影响。异质性分析则发现,信息基础设施建设主要引发生猪价格的整体大幅波动和负向大幅波动,而对生猪价格的小幅波动和正向大幅波动的影响并不显著。基于上述研究结果,提出为养殖户提供风险管理工具等针对性的建议。

关键词：信息基础设施建设 “宽带中国” 生猪价格波动养殖主体分化