检索结果-南通市图书馆

Abundance and sources of particulate polycyclic aromatic hydrocarbons and aromatic acids at an urban site in central China

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第8期142卷 155-168页

作者： Luqi Shang zhe dong Zihan Li Mingkai Wang Zihan Kong Xiao Li Ruiqin Zhang School of Ecology and Environment Zhengzhou UniversityZhengzhou 450001China College of Chemistry Zhengzhou UniversityZhengzhou 450001China Institute of Environmental Sciences Zhengzhou UniversityZhengzhou 450001China

We conducted a simultaneous field study of PM_(2.5)-bound particulate polycyclic aromatic hydrocarbons(PAHs)and aromatic acids(AAs)in a polluted city zhengzhou to explore the concentration,sources and potential conversion pathways between PAHs and AAs in different *** average concentrations of PM_(2.5),28PAHs and 8AAs during the sampling period were 77μg/m^(3),75 ng/m^(3),and 283 ng/m^(3),*** concentration of both28PAHs and 8AAs were highest in winter and lowest in summer with ratios of 6.3 and 2.3,*** with 5-7 rings were the main components of PAHs(52%),followed by 4rings PAHs(30%)and 2-3 rings PAHs(18%).According to the source appointment results obtained by positive matrix factorization,the main sources of PAHs were combustion and vehicle emissions,which account for 37%and 34%,respectively.8AAs were divided into three groups,including four benzene dicarboxylic acids(B2CAs),three benzene tricarboxylic acids(B3CAs)and one benzene tetracarboxylic acid(B4CA).And interspecies correlation analysis with PM_(2.5)source markers were used to investigate potential *** acid(o-Ph)was the most abundant specie of 8AAs(157 ng/m^(3),55%of 8AAs),which was well correlated with ***,B3CAs and B4CA were highly correlated with sulfate and weakly correlated with levoglucosan,suggesting that secondary formation was their main *** logical oxidation products of PAHs,o-Ph and B3CAs showed good correlations with a number of PAHs,indicating possible photochemical oxidation pathway by *** addition,O_(3),NO_(2),temperature and relative humidity have positive effects on the secondary formation of B3CAs.

关键词： Polycyclic aromatic hydrocarbons Aromatic acids Source appointment Secondary formation

Fusion network for small target detection based on YOLO and attention mechanism

在线全文

学校读者我要写书评

暂无评论

Optoelectronics Letters 2024年第6期20卷 372-378页

作者： XU Caie dong zhe ZHONG Shengyun CHEN Yijiang PAN Sishun WU Mingyang School of Information and Electronic Engineering Zhejiang University of Science and TechnologyHangzhou 310012China Research Development Department Hangzhou Xinhe Data Technology Co.Ltd.Hangzhou 311202China College of Mechanical Engineering Zhejiang UniversityHangzhou 310013China

Target detection is an important task in computer vision research, and such an anomaly detection and the topic of small target detection task is more concerned. However, there are still some problems in this kind of researches, such as small target detection in complex environments is susceptible to background interference and poor detection results. To solve these issues, this study proposes a method which introduces the attention mechanism into the you only look once(YOLO) network. In addition, the amateur-produced mask dataset was created and experiments were conducted. The results showed that the detection effect of the proposed mothed is much better.

关键词： Fusion network for small target detection based on YOLO and attention mechanism

Prediction-Based State Estimation and Compensation Control for Networked Systems With Communication Constraints and DoS Attacks

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第11期11卷 2352-2354页

作者： Zhong-Hua Pang Qian Cao Haibin Guo zhe dong IEEE the Key Laboratory of Fieldbus Technology and Automation of Beijing North China University of Technology

Dear Editor,This letter investigates the output tracking control issue of networked control systems(NCSs) with communication constraints and denial-of-service(DoS) attacks in the sensor-to-controller channel,both of w...

关键词：

The transgenerational effects of maternal low-protein diet during lactation on offspring

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Genetics and Genomics 2024年第8期51卷 824-835页

作者： Lin-Jian Gu Li Li Qian-Nan Li Ke Xu Wei Yue Jing-Yi Qiao Tie-Gang Meng Ming-zhe dong Wen-Long Lei Jia-Ni Guo zhen-Bo Wang Qing-Yuan Sun State Key Laboratory of Stem Cell and Reproductive Biology Institute of ZoologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Institute of Laboratory Animal Sciences CAMS&PUMCBeijing 100021China Guangzhou Key Laboratory of Metabolic Diseases and Reproductive Health Guangdong-Hong Kong Metabolism&Reproduction Joint LaboratoryReproductive Medicine CenterGuangdong Second Provincial General HospitalGuangzhouGuangdong 510317China

Environmental factors such as diet and lifestyle can influence the health of both mothers and ***,its transgenerational transmission and underlying mechanisms remain largely ***,using a maternal lactation-period low-protein diet(LPD)mouse model,we show that maternal LPD during lactation causes decreased survival and stunted growth,significantly reduces ovulation and litter size,and alters the gut microbiome in the female LPD-F1 *** transcriptome of LPD-F1 metaphase II(MII)oocytes shows that differentially expressed genes are enriched in female pregnancy and multiple metabolic ***,maternal LPD causes early stunted growth and impairs metabolic health,which is transmitted over two *** methylome alteration of LPD-F1 oocytes can be partly transmitted to the F2 ***,our results reveal that LPD during lactation transgenerationally affects offspring health,probably via oocyte epigenetic changes.

关键词： Lactationdiet Maternal low-proteindiet DNAmethylation Transgenerational effect Oocyte

林徽因《现代住宅设计的参考》及其住宅设计理论内涵初探

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

建筑师 2024年第2期 138-143页

作者：董哲华中科技大学建筑与城市规划学院华中科技大学湖北省城镇化工程技术研究中心

林徽因在《中国营造学社汇刊》第7卷第2期内发表的《现代住宅设计的参考》是《汇刊》中少见的关注现代住宅设计的论文,至今仍不失其学术价值。由于当时艰辛的写作条件,《参考》仅是一篇未完成稿,其内容在发表后近80年中尚未获得专门分... 详细信息

林徽因在《中国营造学社汇刊》第7卷第2期内发表的《现代住宅设计的参考》是《汇刊》中少见的关注现代住宅设计的论文,至今仍不失其学术价值。由于当时艰辛的写作条件,《参考》仅是一篇未完成稿,其内容在发表后近80年中尚未获得专门分析。本文将《参考》作为林徽因长期研究住宅建筑的阶段性成果,梳理其写作内容并尝试补足原文未及介绍的两个案例。在此基础上,本文提出《参考》记录了林徽因对住宅设计中社会调查、经济运营、功能策划、结构建造、能源利用等各个程序的关注,反映了她在住宅研究中科学化的方法论,蕴含着她对于住宅设计的体系性思考。

关键词：林徽因《现代住宅设计的参考》住宅设计理论预制装配式住宅被动式太阳能住宅

卤代烷气体灭火剂促进-抑制瓦斯燃爆特性试验

在线全文

学校读者我要写书评

暂无评论

煤炭科学技术 2024年第4期52卷 265-274页

作者：王涛董哲盛禹淮南凡杨哲杨鹏孟帆罗振敏西安科技大学安全科学与工程学院陕西西安710054

瓦斯爆炸是严重威胁煤矿安全生产的主要灾害之一,开发高效的瓦斯抑爆技术可有效提升瓦斯爆炸事故防控水平,而其重点在于抑爆材料的作用性能。为系统研究典型卤代烷气体灭火剂对瓦斯爆炸的作用效果,采用试验测试和理论分析相结合的方法,... 详细信息

瓦斯爆炸是严重威胁煤矿安全生产的主要灾害之一,开发高效的瓦斯抑爆技术可有效提升瓦斯爆炸事故防控水平,而其重点在于抑爆材料的作用性能。为系统研究典型卤代烷气体灭火剂对瓦斯爆炸的作用效果,采用试验测试和理论分析相结合的方法,系统研究了七氟丙烷(C_(3)HF_(7))、六氟丙烷(C_(3)H_(2)F_(6))和三氟甲烷(CHF_(3))等典型卤代烷气体对甲烷燃爆特性的影响,分别利用20 L球形爆炸装置和自研本生灯层流火焰传播速度系统测试了卤代烷对甲烷爆炸压力参数和层流燃烧速度的作用效果。得到了爆炸压力峰值、最大升压速率、层流燃烧速度等特征参数变化规律和层流火焰形貌演化特性。结果表明:富氧工况下卤代烷随添加体积分数的增大而对甲烷燃爆过程表现出明显的促进−抑制双重作用。在化学当量条件下,仅C_(3)HF_(7)对甲烷爆炸压力峰值、最大升压速率有先促进后抑制的作用,CHF_(3)和C_(3)H_(2)F_(6)均表现出抑制作用;3种卤代烷气体对甲烷层流燃烧速度均表现出抑制作用。在贫氧工况中,3种卤代烷气体对甲烷的爆炸压力峰值,最大升压速率和层流燃烧速度均表现出抑制作用。整体而言,C_(3)H_(2)F_(6)和C_(3)HF_(7)对甲烷爆炸压力特征参数和层流燃烧速度的抑制效果优于CHF_(3)。理论分析结果显示,富氧工况下卤代烷随掺混体积分数的增大而表现出的促进−抑制双重作用,可归因于其对体系反应过程中热释放特性的提升与其主要含F中间产物对H、O和OH等关键自由基的抑制之间的竞争结果。研究结果为瓦斯爆炸防治相关理论研究和技术开发提供一定的理论依据。

关键词：瓦斯爆炸卤代烷爆炸抑制促爆作用爆炸压力层流燃烧速度

在线全文

学校读者我要写书评

暂无评论

双能X射线测定肉类肥瘦比例研究进展

肉类研究 2024年第2期38卷 70-77页

作者：董哲王勤忏王浩同方威视技术股份有限公司北京100083 清华大学工程物理系北京100084

近年来,我国肉类加工行业发展迅猛,自动化和智能化水平逐渐提高,多种肥瘦比例检测技术被应用到肉制品加工和屠宰行业。双能X射线吸收法(dual energy X-ray absorptiometry,DXA)是解决肉制品在线肥瘦比例检测的最佳方法之一,具有精准度... 详细信息

近年来,我国肉类加工行业发展迅猛,自动化和智能化水平逐渐提高,多种肥瘦比例检测技术被应用到肉制品加工和屠宰行业。双能X射线吸收法(dual energy X-ray absorptiometry,DXA)是解决肉制品在线肥瘦比例检测的最佳方法之一,具有精准度高、耗时短、可以对胴体全身进行检测的优势。本文比较当前各种肥瘦比例检测技术的特点,介绍DXA的概念、测量方式,重点探讨DXA在肥瘦比例测定中的应用和研究进展,通过对研究现状、设备类型和存在问题的分析,讨论未来该技术应用的发展方向。

关键词：双能X射线吸收法肉质分析肥瘦比例

在线全文

学校读者我要写书评

暂无评论

转子精加工图自动化设计方法

上海电气技术 2024年第2期17卷 58-61页

作者：董哲上海汽轮机厂有限公司上海200240

针对汽轮机转子承载功能多、结构形式变化多样的特点,基于转子功能—特征结构—工程图视图表达的思路,提出了转子精加工图自动化设计方法。设计了属性定义自动标注方法、典型结构自动标注方法、参数化视图模板驱动方法,开发了数十种基... 详细信息

针对汽轮机转子承载功能多、结构形式变化多样的特点,基于转子功能—特征结构—工程图视图表达的思路,提出了转子精加工图自动化设计方法。设计了属性定义自动标注方法、典型结构自动标注方法、参数化视图模板驱动方法,开发了数十种基于以上三种方法的转子精加工图视图自动标注功能,并设计了工作台对所有功能进行有机整合。基于NX软件二次开发的转子精加工图自动化设计方法能够将转子精加工图中需要人工干预的工程图要素数量由约1000个减少为约20个,使转子精加工图的设计效率提升20倍,具有较高的应用推广价值。

关键词：转子精加工图自动化设计

Kirchberg’s conjecture in the system of Hilbert space factorable mapping spaces

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

Science China Mathematics 2020年第6期63卷 1125-1138页

作者： zhe dong School of Mathematical Sciences Zhejiang UniversityHangzhou 310027China

This study aims to introduce the notions of injectivity, local reflexivity, exactness, and nuclearity in the system(Γ2c(·, ·), γ2c(·)). We find that every dual operator space is injective in the system(Γ2c(·, ·), γ2c(·)) and nuclearity is equivalent to exactness in this system. As a corollary, we prove that Kirchberg’s conjecture on the equivalence of exactness and local reflexivity for C*-algebras is false in this system, i.e., there exists a C*-algebra A that is locally reflexive in this system but is not exact in this system.

关键词： Hilbert space factorable mapping space injectivity local reflexivity exactness nuclearity