检索结果-南通市图书馆

Effects of climate fluctuations on runoff in the headwater region of the Kaidu River in northwestern China

在线全文

学校读者我要写书评

暂无评论

Frontiers of Earth Science 2014年第2期8卷 309-318页

作者： zhongsheng chen Yaning chen State key Laboratory of Geographic Information Science Ministry of Education East China Normal University Shanghai 200062 China State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China

The aim of this study was to analyze the effects of climate fluctuations on runoff in the headwater region of the Kaidu River in northwestern China. For this purpose, precipitation and potential evaporation （PET） data from 5 meteorological stations and the runoff depth data from the Dashankou hydrological station in the headwater region of the Kaidu River from 1960 to 2009 were collected, then the trends and abrupt changes of precipitation, PET and runoff depth were analyzed by means of Mann-Kendall test （M-K test） and Mann-Kendall-Sneyers test （M-K-S test）, respectively. The runoff model driven by precipitation and PET was developed in this work and the sensitivity of runoff to climate fluctuation was simulated under different scenarios. Results showed that the annual precipitation and runoff depth both exhibited an increasing trend over the periods 1960-2009; however, this is not the case for the annual PET. The abrupt changes for annual precipitation, PETand runoff depth all occurred in the early 1990s. The established driving model could well reflect the compli- cated nonlinear relationship among runoff depth, precipitation and PET. The sensitivity analysis indicated that the precipitation had a positive effect on the runoff depth, opposite to what were observed between PET and runoff, and the runoff depth was more sensitive to precipitation than to PET in the headwater region of the Kaidu River.

关键词： climate fluctuation driving model runoffdepth sensitivity analysis

Investigations into sensing characteristics of circular thin-plate electrostatic sensors for gas path monitoring

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

Chinese Journal of Aeronautics 2014年第4期27卷 812-820页

作者： zhongsheng chen Xin Tang Zheng Hu Yongmin Yang Science and Technology on Integrated Logistic Support Laboratory National University of Defense Technology

Circular thin-plate electrostatic sensors are promising in gas path monitoring due to their advantages of non-intrusiveness and easy installation. The spatial sensitivity and filtering effect are two important performance parameters. In this paper, an analytically mathematical model of induced charge on a circular thin-plate electrode is first derived. Then the spatial sensitivity and filtering effect of the circular electrostatic sensor are investigated by numerical calculations. Finally,experimental studies are performed to testify the theoretical results. Both theoretical and experimental results demonstrate that circular thin-plate electrostatic sensors act as a low-pass filter in the spatial frequency domain, and both the spatial filtering effect and the temporal frequency response characteristics depend strongly on the spatial position and velocity of the charged particle. These conclusions can provide guidelines for the optimal design of circular thin-plate electrostatic sensors.

关键词： Circular thin-plate Electrostatic sensor Gas path monitoring Induced charge Spatial filtering effect Spatial sensitivity

基于深度学习的压缩感知重构及其应用现状与展望

在线全文

学校读者我要写书评

暂无评论

电工技术 2024年第3期 32-37,41页

作者：柳浩鹏陈仲生李潮林湖南工业大学电气与信息工程学院湖南株洲412007 常州工学院汽车工程学院江苏常州213032

经典的奈奎斯特采样定理要求采样频率大于两倍信号最大频率,才能重构出原始信号,但是当信号具有稀疏性时,压缩感知方法可突破奈奎斯特采样定理的限制,大大降低采样频率,显著提高数据采集和分析的效率。近年来,压缩感知作为一种全新的稀... 详细信息

经典的奈奎斯特采样定理要求采样频率大于两倍信号最大频率,才能重构出原始信号,但是当信号具有稀疏性时,压缩感知方法可突破奈奎斯特采样定理的限制,大大降低采样频率,显著提高数据采集和分析的效率。近年来,压缩感知作为一种全新的稀疏信号处理框架,已广泛使用于图像重建、稀疏信号重构等领域。随着深度学习技术的快速发展,将各种深度神经网络用于压缩感知领域中,既能提高重构的精度,又能减少重构的时间。通过对公开文献进行广泛调研,介绍了压缩感知重构的基本概念,梳理了常用的压缩感知算法,归纳了深度压缩感知的主要应用领域。最后探讨了当前仍面临的问题及未来的发展趋势。

关键词：深度学习压缩感知图像重建信号重构迁移学习

基于边缘计算改进的MobileNetV1-SSD表面缺陷视觉检测方法

在线全文

学校读者我要写书评

暂无评论

船电技术 2024年第3期44卷 9-14页

作者：汪国平胡博陈仲生侯幸林湖南工业大学电气与信息工程学院湖南株洲412007 南京理工大学瞬态物理国家重点实验室江苏南京210094 常州工学院汽车工程学院江苏常州213032

表面缺陷检测是产品质检的重要工序之一,现有边缘端视觉检测大多存在识别率低、模型结构复杂、部署困难、模型推理实时性差等问题。为此,本文以STM32H747微控制器为边缘设备,基于MobileNetV1-SSD轻量化模型,研究了一种融合CBAM注意力机... 详细信息

表面缺陷检测是产品质检的重要工序之一,现有边缘端视觉检测大多存在识别率低、模型结构复杂、部署困难、模型推理实时性差等问题。为此,本文以STM32H747微控制器为边缘设备,基于MobileNetV1-SSD轻量化模型,研究了一种融合CBAM注意力机制的表面缺陷视觉检测方法。首先,融合CBAM注意力机制,添加在最后一层的特征提取网络之后,使缺陷目标在检测模型中的特征表达能力得到增强,模型在仅增加少量的参数量的基础上提升模型的检测准确率;其次,对CBAM-MobilenetV1-SSD模型进行预处理;最后,采用X-CUBE-AI工具包在STM32H747微控制器中实现了模型的移植和部署。通过对比实验表明,融合CBAM注意力机制的模型mAP达到83.75%,精度比原算法提高2.75%,参数量仅为1.67M,模型大小为622KB,且部署在边缘设备对软包锂电池表面缺陷检测精度有显著提升。

关键词：表面缺陷检测边缘计算 STM32微控制器 MobileNetV1-SSD CBAM

在线全文

学校读者我要写书评

暂无评论

旋转叶片流固耦合振动对叶端定时测振的影响

常州工学院学报 2024年第1期37卷 1-9,33页

作者：曹臻博冯俊萍陈仲生赵景波江苏理工学院汽车与交通工程学院江苏常州213001 常州工学院汽车工程学院江苏常州213032

叶端定时是一种先进的旋转叶片在线振动监测方法,但其测量准确性受其测点位置变化影响较大,如何选取合适的测点具有重要研究价值。为考虑叶片颤振及其流固耦合振动对测点位置的影响,设置流场圆柱绕流产生涡阶,并对不同转速和裂纹位置下... 详细信息

叶端定时是一种先进的旋转叶片在线振动监测方法,但其测量准确性受其测点位置变化影响较大,如何选取合适的测点具有重要研究价值。为考虑叶片颤振及其流固耦合振动对测点位置的影响,设置流场圆柱绕流产生涡阶,并对不同转速和裂纹位置下旋转叶片的扭转情况进行分析。计算比较离心载荷时正常叶片的扭转振动,流固耦合下正常叶片、裂纹叶片的扭转振动及叶端各点扭转偏移量对叶端定时测振测点位置的影响。结果表明:流固耦合作用下,转速和裂纹位置对叶片的扭转振动影响较大;叶端定时测振传感器在转速较低时应安装在靠近叶片前缘处,而转速较高时应安装在靠近叶端中间位置。

关键词：叶端定时振动监测旋转叶片测点位置流固耦合

在线全文

学校读者我要写书评

暂无评论

清代四川水灾时空特征及受灾比风险测度

地球环境学报 2024年第2期15卷 207-223页

作者：尹肇麒李卫朋陈忠升熊梅汪秀娟西华师范大学地理科学学院南充637000 西华师范大学四川省干旱河谷土壤侵蚀监测与控制工程实验室南充637000 西华师范大学历史文化学院南充637000

通过历史记录对清代四川省水灾逐年分等定级,以此研究清代四川水灾的时空变化特征。同时,基于信息扩散理论计算出受灾风险概率。结果表明:(1)清代(1644—1911年)共发生水灾1409县次,1861—1890年为水患高发期,1825年后水灾强度显著上升... 详细信息

通过历史记录对清代四川省水灾逐年分等定级,以此研究清代四川水灾的时空变化特征。同时,基于信息扩散理论计算出受灾风险概率。结果表明:(1)清代(1644—1911年)共发生水灾1409县次,1861—1890年为水患高发期,1825年后水灾强度显著上升。10 a尺度下水灾强度存在三次高峰,30 a尺度下清末期水灾强度持续增强。前期水灾周期为中长期振荡,1825年后水灾强度显著提高且以中短(8—15 a)周期性振荡为主。(2)水灾密集区主要位于山地-平原交界处的成都府、眉州、雅州府东部区域,受灾指数基尼系数为0.4615,水患平均中心位移较小。(3)全川受灾风险概率在受灾比为0.05—0.15时迅速下降,同等受灾比(0.2以下时)下,川东道受灾风险概率最高;而受灾比高于0.2时,川北道受灾风险最高。(4)东亚季风增强、人口暴露度增加、政治经济动荡造成的社会韧性下降和生态破坏可能是清末四川省水灾强度提高和规模扩大的重要原因。

关键词：清代水灾时空特征受灾风险四川省

华南地区3188例结直肠癌错配修复蛋白的表达情况及临床病理特征

在线全文

学校读者我要写书评

暂无评论

中国临床新医学 2024年第7期17卷 753-758页

作者：付巧玉金田恩蒋汉文洪娟方楚天陈忠生广州达安临床检验中心广东510520

目的探讨华南地区结直肠癌组织中错配修复(MMR)蛋白的表达情况及临床病理特征。方法收集广州达安临床检验中心2019年1月至2023年12月存档的结直肠癌病例3188例,采用免疫组化法检测结直肠癌组织中MLH1、PMS2、MSH2、MSH6蛋白的表达情况,... 详细信息

目的探讨华南地区结直肠癌组织中错配修复(MMR)蛋白的表达情况及临床病理特征。方法收集广州达安临床检验中心2019年1月至2023年12月存档的结直肠癌病例3188例,采用免疫组化法检测结直肠癌组织中MLH1、PMS2、MSH2、MSH6蛋白的表达情况,进一步分析其与临床病理特征的关系。结果在3188例结直肠癌中,发现错配修复蛋白缺失(MMRd)254例(缺失率为8.0%);MLH1^(-)/PMS2^(-)共146例,占MMRd的57.5%;MSH2^(-)/MSH6^(-)共35例,占MMRd的13.8%。不同年龄、肿瘤部位及分化程度的MMRd发生率差异有统计学意义(P<0.05)。分析其中646例结直肠癌根治术样本,发现MMRd与肿瘤最大径、淋巴结转移、脉管侵犯、神经侵犯及癌结节密切相关(P<0.05)。结论MMRd在华南地区结直肠癌中的发生率为8.0%,好发于年轻女性,肿瘤部位多见于回盲部及升结肠,以低分化为主。MMRd肿瘤常表现为肿瘤直径较大(≥5 cm)、淋巴结转移少见、癌结节少见、无脉管侵犯及无神经侵犯。

关键词：结直肠癌错配修复蛋白微卫星不稳定免疫组化华南

Variations of temperature and precipitation of snowmelt period and its effect on runoff in the mountainous areas of Northwest China

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2013年第1期23卷 17-30页

作者： LI Baofu chen Yaning chen zhongsheng LI Weihong ZHANG Baohuan State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography CAS Urumqi 830011 China University of Chinese Academy of Sciences Beijing 100049 China

Water resources in the arid land of Northwest China mainly derive from snow and glacier melt water in mountainous areas. So the study on onset, cessation, length, tempera- ture and precipitation of snowmelt period is of great significance for allocating limited water resources reasonably and taking scientific water resources management measures. Using daily mean temperature and precipitation from 8 mountainous weather stations over the pe- riod 1960-2010 in the arid land of Northwest China, this paper analyzes climate change of snowmelt period and its spatial variations and explores the sensitivity of runoff to length, temperature and precipitation of snowmelt period. The results show that mean onset of snowmelt period has shifted 15.33 days earlier while mean ending date has moved 9.19 days later. Onset of snowmelt period in southern Tianshan Mountains moved 20.01 days earlier while that in northern Qilian Mountains moved only 10.16 days earlier. Mean precipitation and air temperature increased by 47.3 mm and 0.857~C in the mountainous areas of Northwest China, respectively. The precipitation of snowmelt period increased the fastest, which is ob- served in southern Tianshan Mountains, up to 65 mm, and the precipitation and temperature in northern Kunlun Mountains increased the slowest, an increase of 25 mm and 0.617~C, respectively, while the temperature in northern Qilian Mountains increased the fastest, in- creasing by 1.05~C. The annual runoff is also sensitive to the variations of precipitation and temperature of snowmelt period, because variation of precipitation induces annual runoff change by 7.69% while change of snowmelt period temperature results in annual runoff change by 14.15%.

关键词： snowmelt period temperature precipitation runoff mountainous areas of Northwest China

Effect of Temperature and Grain Boundary on Void Evolution in Irradiated Copper:A Phase-Field Study

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第9期37卷 1621-1632页

作者： Qionghuan Zeng Yiming chen zhongsheng Yang Yunhao Huang Zhijun Wang Junjie Li Jincheng Wang tate Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Science and Technology On Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu610213China

The continued existence of high-energy radiation in nuclear reactors at high temperatures results in the formation of radiation-induced voids,which will further lead to inevitable swellings of polycrystalline structural components and thus premature failures.A deep understanding of the effect of temperature and grain boundary on void evolution in irradiated copper is significant for preventing this kind of ***,the phase-field method was employed to study void evolution in irradiated copper under different temperatures and grain *** results show that,due to the different sensitivities of point defect production rate and vacancy diffusion rate to temperature changes,both the nucleation-growth rate and the coarsening rate during void evolution increase first and then decrease with increasing temperature;moreover,the nucleation mechanism exhibits site-saturated nucleation at low temperatures while continuous nucleation at high *** presence of grain boundary can accelerate the emergence of void because grain boundaries can absorb more interstitials than *** finer the grain size,the stronger inhibitory effect of grain boundaries on the growth rate of void,due to the formation of void denuded zone near grain *** high temperatures,the growth rate of void in fine grains is significantly reduced due to the increase of vacancy diffusion rate and the enhancement of sink effect of grain boundary on vacancy.

关键词： Void evolution Phase-field method Temperature Grain boundary