检索结果-南通市图书馆

一种基于耦合电感的零电流纹波功率因数校正变换器

在线全文

学校读者我要写书评

暂无评论

电工技术学报 2022年第18期37卷 4732-4744页

作者：林通江平姚佳南京理工大学自动化学院南京210094 南京晨光集团有限责任公司南京210006

为了降低传统Boost功率因数校正(PFC)变换器的输入电流纹波,改善输入电流的总谐波畸变率(THD),提升PFC效果,该文提出一种基于耦合电感的零电流纹波PFC变换器。首先,基于零电流纹波工作原理分析并推导PFC工况下的电路参数设计方法。分析... 详细信息

为了降低传统Boost功率因数校正(PFC)变换器的输入电流纹波,改善输入电流的总谐波畸变率(THD),提升PFC效果,该文提出一种基于耦合电感的零电流纹波PFC变换器。首先,基于零电流纹波工作原理分析并推导PFC工况下的电路参数设计方法。分析表明,由于所增加的辅助电感仅用于消除电流纹波而不参与主功率传输,因此其体积远小于传统BoostPFC的输入滤波器。其次,在拓扑研究基础上结合零电流纹波特性,提出采用数字单周期控制策略,给出数字控制器的设计及实现方法。最后,通过实验将所提出拓扑的性能与传统BoostPFC进行对比。实验结果表明,该文所提出的基于耦合电感的零电流纹波PFC变换器输入电感电流纹波近似为零,THD明显低于传统Boost PFC变换器,且功率因数(PF)显著提升。

关键词：数字单周期控制零电流纹波耦合电感功率因数校正

同方期刊数据库

“南腔北调”:语言和思想的分歧与沟通——从鲁迅《南腔北调集》谈起

在线全文

学校读者我要写书评

暂无评论

北京社会科学 2015年第4期 22-29页

作者：颜同林贵州师范大学文学院贵阳550001

鲁迅的杂文集《南腔北调集》是民国社会特定时期的产物,其"南腔北调"既是一个指涉参杂南北方音的名词,同时也是民国历史场域中一个具有更深层次内涵的文化思想隐喻。走南闯北的人生体验,汇聚成了鲁迅以多方言混合为基础的语言与思想观念... 详细信息

鲁迅的杂文集《南腔北调集》是民国社会特定时期的产物,其"南腔北调"既是一个指涉参杂南北方音的名词,同时也是民国历史场域中一个具有更深层次内涵的文化思想隐喻。走南闯北的人生体验,汇聚成了鲁迅以多方言混合为基础的语言与思想观念,其语言和思想有诸多分歧,也有内在沟通,由此塑造出一个颇具民国性格的文人形象。从纷乱的语言到驳杂的思想,后者更为重要。鲁迅以杂文这一独特的话语方式,张扬生命个体的思想独立与自由,在民国文学天空中绽放出了璀灿的思想之花。

关键词：鲁迅《南腔北调集》语言分歧文学思想民国历史

东北粮食主产区农户主导型农村土地流转价格影响因素

在线全文

学校读者我要写书评

暂无评论

农业工程学报 2017年第18期33卷 260-266页

作者：林彤宋戈乔元波东北大学文法学院沈阳110169 山东大学县域发展研究院青岛266200

分析各因素对农村土地流转价格的影响方向与作用强度可为确定土地承包经营权流转价格提供依据。该文以黑龙江省农村固定观察点14个村的转入方农户为样本,采用相关性分析和多元线性回归方法分别确定单因素与多因素对流转价格的影响,并对... 详细信息

分析各因素对农村土地流转价格的影响方向与作用强度可为确定土地承包经营权流转价格提供依据。该文以黑龙江省农村固定观察点14个村的转入方农户为样本,采用相关性分析和多元线性回归方法分别确定单因素与多因素对流转价格的影响,并对比分析各因素对高于均价组和低于均价组中流转价格的影响差异。结果表明:1)单因素对流转价格的影响分析中,耕地粮食产量对流转价格产生显著正向影响,是影响流转价格最重要的因素;2)多因素对流转价格的影响分析中,耕地粮食产量、村域经济发达程度、县域交通通达性、户主年龄对流转价格产生显著正向影响,县域人均GDP、与市中心距离对流转价格产生显著负向影响;3)对比各因素对高于均价组和低于均价组的影响,发现交通通达性、与市中心距离对高于均价组流转价格的影响方向与总样本一致,这些因素对低于均价组流转价格的影响方向与总样本相反。需明确耕地信息、了解地区经济与交通情况,为确定土地流转价格、完善农村土地流转市场创造条件。

关键词：土地利用粮食农村农户主导型农村土地承包经营权流转东北粮食主产区

在线全文

学校读者我要写书评

暂无评论

从教体验与鲁迅现代小说的教育书写

北京社会科学 2014年第8期 67-73页

作者：颜同林贵州师范大学文学院贵阳550001

著书立说与从教"树人"是鲁迅一生立足于民国社会并改造国民性的两块基石。结合鲁迅的教育管理经历与从教体验,从民国教育文化的角度探讨《呐喊》与《彷徨》中的教育书写,既可以再现民国教员形象,也能对民国教育机制进行部分还原。鲁迅... 详细信息

著书立说与从教"树人"是鲁迅一生立足于民国社会并改造国民性的两块基石。结合鲁迅的教育管理经历与从教体验,从民国教育文化的角度探讨《呐喊》与《彷徨》中的教育书写,既可以再现民国教员形象,也能对民国教育机制进行部分还原。鲁迅小说中灰色而失败的教育理念虽然带有个人的偏见,但可以看做是具有痛感的近现代教育的"野史"资料,是民国教育及其机制本身的艺术呈现。

关键词：从教体验鲁迅小说教育书写反教育

在线全文

学校读者我要写书评

暂无评论

高速铁路接触网精调定额的研究

铁道工程学报 2013年第5期30卷 82-86页

作者：张桐林铁道部经济规划研究院北京100038

研究目的:高速铁路工程技术、施工工艺、设备、器材先进,必然对设计、施工和运营管理等诸多方面有较高的要求。高速铁路接触网精调是满足竣工验收必不可少的施工过程,当前铁路工程电化定额中缺乏高速铁路接触网精调的相关子目,为合理确... 详细信息

研究目的:高速铁路工程技术、施工工艺、设备、器材先进,必然对设计、施工和运营管理等诸多方面有较高的要求。高速铁路接触网精调是满足竣工验收必不可少的施工过程,当前铁路工程电化定额中缺乏高速铁路接触网精调的相关子目,为合理确定和控制工程造价,需研究并编制高速铁路接触网精调定额。研究结论:(1)高速铁路接触网定额应按照静态精调和动态精调分别设置子目,其中动态精调还应按设计速度250 km/h、300 km/h和350 km/h分别设置子目;(2)在合理施工组织下,对接触网静态精调和动态精调消耗的工料机消耗量进行测定并测算综合产量,最终确定接触网静态精调的基期价格为3 350.58元/条km,设计速度250 km/h、300 km/h和350 km/h接触网动态精调的基期价格分别为4 427.13元/条km、5 060.29元/条km和6 481.25元/条km。

关键词：高速铁路接触网精调定额

内激励型振荡衰减流作用下输流管道动力不稳定分析

在线全文

学校读者我要写书评

暂无评论

振动与冲击 2021年第3期40卷 284-290页

作者：张挺林震寰林通张恒福州大学土木工程学院福州350116 中国电建集团贵阳勘测设计研究院有限公司贵阳550081

振荡衰减流作为一种内激励形式,对输流管道的稳定性和共振特性将产生影响。基于输流管道横向振动运动微分方程,引入指数衰减函数模拟水锤发生时流速呈现的振荡衰减特性,推导得到内激励型振荡衰减流作用下输流管道动力不稳定区域的表达... 详细信息

振荡衰减流作为一种内激励形式,对输流管道的稳定性和共振特性将产生影响。基于输流管道横向振动运动微分方程,引入指数衰减函数模拟水锤发生时流速呈现的振荡衰减特性,推导得到内激励型振荡衰减流作用下输流管道动力不稳定区域的表达式。在无衰减周期脉动流激励条件下,计算得到两种不同支撑输流管道的不稳定区域,与前人数值研究结果吻合良好。同时将引入的流速表达式与水锤条件下黏弹性输流管道模型计算得到的流速时程进行对比,表明所提出的流速表达式能较好地反映水锤激励下输流管道内水流的双向衰减特性。进一步分析了衰减特征参数对两端简支输流管道不稳定区域的影响,结果表明,内激励型振荡衰减流对于输流管道横向振动的影响不容忽视,当流速衰减系数b增加,不稳定区域向下偏移,且初始流速u 0增大,偏移现象越明显;同时随着时间τ的推移和衰减系数b的增加,流速衰减越快,不稳定区域闭合加快,当管道内流速衰减至0时,水锤过程结束,管道不稳定区域消失。

关键词：振荡衰减流内激励输流管道横向振动动力不稳定区域

Mammography and ^(99m)Tc-MIBI scintimammography inbreast cancer diagnosis

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2000年第4期11卷 213-217页

作者： ZHU Hui-Qing, lin Xiang-tong, LIU Yong-Chang, REN Chang-Cai, HE Wan-Ting, GONG Hai-Xia (Huashan Hospital, Medical Center of Fundan University, Shanghai 200040) 复旦大学上海 200040

The aim of this work has been to evaluate whether a diagnostic protocol based on the joint use of mammography and 99mTc-MIBI scintimammography can help to distinguish the lesions and to reduce the number of biopsies required in patients with suspected breast cancer. A total of 58 women were evaluated by palpation, mammography, scintimammography. Twenty-four patients were scintimammographed with 99mTc-MIBI at 10min after injection. Thirty-four patients were taken doublephase scintimammography with 99mTc-MIBI 10min and 60-90min after injection. Based on mammography, the supicion degrees of malignancy were rated, and 30 results of malignancy were confirmed by histopathology. Based on mammography, 18 lesions were considered to be most probably benign (of which 3 were histopathologi-cally breast cancer), 19 as indeterminate (of which 9 were histopathologically breast cancer), and 21 as malignant (of which 18 were histopathologically breast cancer). The results of early and delayed phases 99mTc-MIBI scintimammography were the same. The sensitivity, specificity and accuracy of scintimammography were 74.29%, 86.96% and 79.31%, respectively. Scintimammography gave 16 correct diagnosis in 19 mammogram indeterminate (84.2%) and demonstrated 5 out of 8 cases axillary lymph nodes metastasis (62.5%). These studies show that 99mTc-MIBI scintimammography used as a complementary testing technique to mammography is useful in the examination of patients with suspected breast cancer. The adoption of a joint mammography-scintimammography diagnostic protocol conld considerably reduce the number of biopsies performed in patients with lesions of indeterminate mammographic suspicion of malignancy.

关键词： ^99mTc-MIBI 锝99 放射性核素标记放射性治疗药物乳腺癌乳房X线照片

Changes of microbial diversity during pyrite bioleaching

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2020年第5期27卷 1477-1483页

作者： YIN Lu YANG Hong-ying LI Xiang tong lin-lin JIN Zhe-nan ZHANG Qin School of Metallurgy Northeastern UniversityShenyang 110819China

Microorganisms,one of the key factors affecting the bioleaching process,change the components of extracellular polymeric substance(EPS)and community structure to survive in leaching *** this work,Fourier transform infrared(FTIR),X-ray powder diffraction(XRD)and 16S rDNA high-throughput sequence analyses were used to reveal the microbial changes in planktonic and sessile phases during *** results showed the occupation of sessile cells decreased from 66.2%to(10±3)%.After bioleaching,the planktonic and sessile cells have similar EPS,but they are different from the original *** dissolution mainly occurs at the early and late stages with the decreasing of particle diameter,by 50%and 40%,*** 16S rDNA gene based sequence analysis results in total of 1117420 Reads across the six samples,presented among 7 phyla,9 classes,17 orders,23 families and 31 *** Leptospirillum and Sulfobacillus are the main bacteria at the early and middle stages,and Leptospirillum is the main genus at the end of *** and Acidovorax are special genera in sessile cells and Weissella is special in planktonic ones.

关键词： pyrite dissolution sessile cells planktonic cells high-throughput sequence analysis microbial diversity bioleaching stage

Petroleum geology and sub-source hydrocarbon accumulation of Permian reservoirs in Jinan Sag,eastern Junggar Basin,NW China

在线全文

学校读者我要写书评

暂无评论

Petroleum Exploration and Development 2023年第3期50卷 558-572页

作者： LI Jianzhong CHEN Xuan YANG Runze lin tong YANG Fan MA Qiang GOU Hongguang WEI Yanzhao lin lin PetroChina Tuha Oilfield Company Hami 839009China PetroChina Research Institute of Petroleum Exploration and Development Beijing 100083China

According to the latest drilling and the analysis of the burial history,source rock evolution history and hydrocarbon accumulation history,the sub-source hydrocarbon accumulation characteristics of the Permian reservoirs in the Jinan Sag,eastern Junggar Basin,are clarified,and the hydrocarbon accumulation model of these reservoirs is *** results are obtained in four ***,the main body of the thick salified lake basin source rocks in the Lucaogou Formation has reached the mature stage with abundant resource ***-scale reservoirs are developed in the Jingjingzigou,Wutonggou and Lucaogou ***,there are multiple sets of good regional seals,the source-reservoir-caprock assemblage is good,and there are three reservoir-forming assemblages:sub-source,intra-source and ***,dissolution,hydrocarbon charging and pore-preserving effect,and presence of chlorite film effectively increase the sub-source pore *** charging is earlier than the time when the reservoir becomes densified,which improves the efficiency of hydrocarbon ***,buoyancy and source-reservoir pressure difference together constitute the driving force of oil charging,and the micro-faults within the formation give the advantage of"source-reservoir lateral docking"under the source *** can be critical channels for efficient seepage and continuous charging of oil in different ***,the Jingjingzigou Formation experienced three periods of oil accumulation in the Middle-Late Permian,Middle-Late Jurassic and Late Neogene,with the characteristics of long-distance migration and accumulation in early stage,mixed charging and accumulation in middle stage and short-distance migration and high-position accumulation in late *** discovery and theoretical understanding of the Permian reservoirs in the Jinan Sag reveal that the thrust belt has good conditions for forming large reservoirs,and it is promising for exploration.T

关键词： Junggar Basin Fukang fault zone Jinan Sag Permian Jingjingzigou Formation hydrocarbon accumulation conditions sub-source hydrocarbon accumulation