期刊文献+
共找到2,592篇文章
< 1 2 130 >
每页显示 20 50 100
A Journey of Healing——Tracing the Beauty of Life in The Country of the Pointed Firs
1
作者 WANG Ru 《海外英语》 2017年第17期167-169,共3页
There is an amazing healing power in the novel The Country of the Pointed Firs embodied in nature and the local people. Reading this novel, everyone can be the narrator who has experienced a journey of healing in Dunn... There is an amazing healing power in the novel The Country of the Pointed Firs embodied in nature and the local people. Reading this novel, everyone can be the narrator who has experienced a journey of healing in Dunnet Landing during her interactions with the coastal natural sceneries and the lovely local residents in that in those small islands. 展开更多
关键词 HEALING THOREAU NATURE WALDEN The Country of the Pointed firs
在线阅读 下载PDF
Multi-year analyses on three populations reveal the first stable QTLs for tolerance to rain-induced fruit cracking in sweet cherry (Prunus avium L.) 被引量:6
2
作者 Jose Quero-Garcia Philippe Letourmy +4 位作者 Jose Antonio Campoy Camille Branchereau Svetoslav Malchev Teresa Barreneche Elisabeth Dirlewanger 《Horticulture Research》 SCIE 2021年第1期1818-1833,共16页
Rain-induced fruit cracking is a major problem in sweet cherry cultivation.Basic research has been conducted to disentangle the physiological and mechanistic bases of this complex phenomenon,whereas genetic studies ha... Rain-induced fruit cracking is a major problem in sweet cherry cultivation.Basic research has been conducted to disentangle the physiological and mechanistic bases of this complex phenomenon,whereas genetic studies have lagged behind.The objective of this work was to disentangle the genetic determinism of rain-induced fruit cracking.We hypothesized that a large genetic variation would be revealed,by visual field observations conducted on mapping populations derived from well-contrasted cultivars for cracking tolerance.Three populations were evaluated over 7–8 years by estimating the proportion of cracked fruits for each genotype at maturity,at three different areas of the sweet cherry fruit:pistillar end,stem end,and fruit side.An original approach was adopted to integrate,within simple linear models,covariates potentially related to cracking,such as rainfall accumulation before harvest,fruit weight,and firmness.We found the first stable quantitative trait loci(QTLs)for cherry fruit cracking,explaining percentages of phenotypic variance above 20%,for each of these three types of cracking tolerance,in different linkage groups,confirming the high complexity of this trait.For these and other QTLs,further analyses suggested the existence of at least two-linked QTLs in each linkage group,some of which showed confidence intervals close to 5 cM.These promising results open the possibility of developing marker-assisted selection strategies to select cracking-tolerant sweet cherry cultivars.Further studies are needed to confirm the stability of the reported QTLs over different genetic backgrounds and environments and to narrow down the QTL confidence intervals,allowing the exploration of underlying candidate genes. 展开更多
关键词 FIR CULTIVAR LINKAGE
原文传递
Inheritance of growth and survival in two 9-year-old, open-pollinated progenies of an advanced breeding population of Chinese firs in southeastern China 被引量:7
3
作者 Renhua Zheng Zhou Hong +4 位作者 Shunde Su Liming Bian Hui Xiao Jisen Shi Harry X. Wu 《Journal of Forestry Research》 SCIE CAS CSCD 2016年第5期1067-1075,共9页
Tree growth traits (tree height, DBH and stem volume) and survival from two 9-year-old, open-pollinated progeny tests of Chinese fir were investigated for heri- tability, genotype × environment interaction, age... Tree growth traits (tree height, DBH and stem volume) and survival from two 9-year-old, open-pollinated progeny tests of Chinese fir were investigated for heri- tability, genotype × environment interaction, age-age genetic correlation and selection efficiency. The 97 and 79 families planted at two sites were collected from the thirdcycle seed orchard. Individual heritability was estimated between 0.05 and 0.21 for tree height, DBH, and volume and between 0.45 and 1.0 for survival. Family heritability was between 0.20 and 1.14. Significant genotype x envi- ronment interaction was observed for the three growth traits. Type B genetic correlation was between 0.41 and 0.67 with an increasing trend as tree grows. High age-age genetic correlation was observed with correlation reaching 0.9 after age 4 for height, DBH, and volume. The genetic gains were estimated at 3.26, 3.39 and 5.98 % for tree height, DBH, and volume with 10 % selection intensity. The implication for advanced tree breeding in Chinese fir is discussed. 展开更多
关键词 Chinese fir - Progeny test Heritability -Genetic gain
在线阅读 下载PDF
First Youth Editorial Committee Meeting of Naihuo Cailiao and China's Refractories Held
4
《China's Refractories》 CAS 2022年第3期46-47,共2页
On July 11,2022,the firast youth editorial committee meeting of Naihuo Cailiao(Refractoriea,in Chinese,bi monthly)and China's Refractories(in English,quarterly)was held in Changsha,China.The first youth editorial ... On July 11,2022,the firast youth editorial committee meeting of Naihuo Cailiao(Refractoriea,in Chinese,bi monthly)and China's Refractories(in English,quarterly)was held in Changsha,China.The first youth editorial com mittee includes 47 members,who come from China Iron&Steel Research Institute Group,Henan University of Sci ence and Technology,Hunan University,Institute of Metal Research of Chinese Academy of Sciences,Jiangsu Jingxin New Materials Co.,Ltd,Kemeos(China)Aluminate Technologies Co.,Ltd,Luoyang Institute of Science and Technology,Northeastem University,RHI Magnesita,Shanghai University,Sinosteel Luonai Materials Technology Corporation,Sinosteel Luoyang Institute of Refractories Research Co.,Ltd,Tianjin University,University of Science and Technology Beijing,Wuhan University of Science and Technology,Wuhan University of Technology.Xian Uni versity of Architecture and Technology.Zhejiang University,and Zhengzhou University. 展开更多
关键词 REFRACTORIES NORTHEAST fir
在线阅读 下载PDF
China Succeeds in First Mars Landing
5
《China Today》 2021年第6期6-11,共6页
The lander carrying China’s first Mars rover has touched down on the red planet,the China National Space Administration(CNSA)confirmed on the morning of May 15.It is the first time China has landed a probe on a plane... The lander carrying China’s first Mars rover has touched down on the red planet,the China National Space Administration(CNSA)confirmed on the morning of May 15.It is the first time China has landed a probe on a planet other than Earth.“The Mars exploration mission has been a total success,”Zhang Kejian,head of the CNSA,announced at the Beijing Aerospace Control Center.“It’s another important milestone for China’s space exploration。” 展开更多
关键词 PLANET EARTH FIR
在线阅读 下载PDF
FAMILY FIRS
6
《The World of Chinese》 2016年第1期26-27,3,共3页
It is said that there is nothing more important than family, but as the vicissitudes of modern life impose new opportunities and strictures, so too do the solutions. The two-child bombshell still has folks reeling wit... It is said that there is nothing more important than family, but as the vicissitudes of modern life impose new opportunities and strictures, so too do the solutions. The two-child bombshell still has folks reeling with the possibilities, and families are now pressed with a very important question: should we? Similarly, tradition has fallen to pragmatism with the rise of the househusband in China. But, there are also those often left out of the family debate: the elderly, as China faces grave questions about its aging population. 展开更多
关键词 impose fallen NOTHING DEBATE TRADITION GRAVE FAMILY firs QUESTIONS possibilities pressed
原文传递
Isolation and Characterization of Monkeypox Virus from the First Case of Monkeypox—Chongqing Municipality,China,2022 被引量:10
7
作者 Baoying Huang Hua Zhao +11 位作者 Jingdong Song Li Zhao Yao Deng Wen Wang Roujian Lu Wenling Wang Jiao Ren Fei Ye Houwen Tian Guizhen Wu Hua Ling Wenjie Tan 《China CDC weekly》 2022年第46期1019-1024,共6页
Introduction:The first imported case of monkeypox(MPX)from the mainland of China was reported in September 2022.Herein,the study reports the isolation and characterization of MPX virus(MPXV)in this case.Methods:Clinic... Introduction:The first imported case of monkeypox(MPX)from the mainland of China was reported in September 2022.Herein,the study reports the isolation and characterization of MPX virus(MPXV)in this case.Methods:Clinical specimens including skin blister fluid,oropharyngeal and nasopharyngeal swabs,and blood were collected and inoculated onto Vero cells.The isolated virus was identified as MPXV using quantitative polymerase chain reaction(qPCR),cytopathic effects(CPEs),immunofluorescence assay(IFA)and transmission electron microscopy(TEM).Plaque assays were employed to quantify infectious plaque-forming units(PFUs).The plaque reduction neutralization test(PRNT)was developed to determine the neutralizing antibody(nAb)against MPXV.Results:MPXV replication was confirmed with qPCR.Typical CPEs were observed 48 h postincubation.The isolated virus was named MPXV-B.1-China-C-Tan-CQ01.IFA showed that MPXV reacted with serum of MPX case.Orthopoxvirus morphology was observed using TEM.The virus titer increased to>106 PFU/mL after three passages.The serum PRNT 50%neutralization titer(NT50)was 35 for the MPX patient 6 days after symptom onset.Discussion:The study successfully isolated the first MPXV strain in the mainland of China,MPXV-B.1-China-C-Tan-CQ01.Infectious titration and PRNT methods have been developed.The study provides key resources and technical platforms for further research as well as anti-viral drug and vaccine development against MPX. 展开更多
关键词 MAINLAND CHONGQING FIR
原文传递
First Case Report of Cystic Echinococcosis Caused by G7 Genotype Echinococcus intermedius Confirmed by Genetic Sequencing—Southern China,December 2023
8
作者 De Wu Jiayi Zhang +10 位作者 Jieling Wang Yangyang Zhao Lei Wang Qiang Mao Haisen Lin Gang Yao Guanting Zhang Xu Wang Chuizhao Xue Ying Wang Jingdiao Chen 《China CDC weekly》 SCIE CSCD 2024年第23期558-562,共5页
What is already known about this topic?Echinococcosis exhibits a global distribution.In China,the primary endemic area is the northwest region.In December 2023,we documented a case of echinococcosis in an individual l... What is already known about this topic?Echinococcosis exhibits a global distribution.In China,the primary endemic area is the northwest region.In December 2023,we documented a case of echinococcosis in an individual lacking any travel or residential history in endemic regions.What is added by this report?This is the first laboratory-confirmed case of hepatic echinococcosis reported in Guangdong Province,associated with the G7 genotype of Echinococcus granulosus(E.granulosus).The most probable mode of transmission is a local infection resulting from E.granulosus introduced from endemic regions.What are the implications for public health practice?As the circulation of agricultural products increases,it is essential to enhance the quarantine and management of livestock from epidemic areas to prevent and control the spread of echinococcosis to non-epidemic regions. 展开更多
关键词 travel fir NORTHWEST
原文传递
一种组合算法在随钻电磁波信号解调中的应用 被引量:1
9
作者 何巍 陆建勋 《现代电子技术》 北大核心 2025年第15期64-70,共7页
在电磁随钻测量中,由于信号衰减和噪声干扰,传统相干解调方法误码率高,导致数据解码不准确。为了解决这一问题,文中设计了一种有限冲激响应(FIR)滤波和自适应滤波相组合的方法,旨在提高解调的准确性。该方法首先利用FIR滤波算法去除带... 在电磁随钻测量中,由于信号衰减和噪声干扰,传统相干解调方法误码率高,导致数据解码不准确。为了解决这一问题,文中设计了一种有限冲激响应(FIR)滤波和自适应滤波相组合的方法,旨在提高解调的准确性。该方法首先利用FIR滤波算法去除带外噪声;然后将滤波后的信号送入两个具有不同参考信号的自适应滤波器。通过比较这两个滤波器的输出信号进行判决,从而获得解码后的数据。为了验证所提方法的效果,使用仿真软件对两种不同噪声条件下的电磁波通信过程进行模拟。仿真结果证明:与传统相干解调方法相比,在高斯白噪声环境下、码元速率为2 b/s时,该方法信噪比提高1 dB左右,误码率差别不大;在码元速率为0.5 b/s时,信噪比提高了约6 dB,误码率降低了约8%。在现场噪声环境下,组合算法的误码率降低了约4%。因此在相同的信噪比条件下,所提方法能够显著降低误码率,展现出更优的解调性能。 展开更多
关键词 EM-MWD 随钻测量 FSK信号 调制解调 FIR滤波 自适应算法
在线阅读 下载PDF
White-naped crane photographed for the first time in Dongxihu
10
作者 Dai Donghui Cai Xinxing 《Changjiang Weekly》 2023年第4期6-6,共1页
"A total of 37 graycranes and one white-napedcrane have been confirmed atthe spot after careful observation!"Recently,Yan Jun,president of the Wuhan Birdwatching Association,took the first photo of thewhite-... "A total of 37 graycranes and one white-napedcrane have been confirmed atthe spot after careful observation!"Recently,Yan Jun,president of the Wuhan Birdwatching Association,took the first photo of thewhite-naped crane,anational key protected bird,in the Dongxihu lake area,while carrying out observation and research of migratory birds. 展开更多
关键词 WHITE protected FIR
在线阅读 下载PDF
FIR数字带通滤波器实验设计
11
作者 姜恩华 窦德召 +1 位作者 许学杰 周正 《商丘师范学院学报》 2025年第9期26-29,共4页
借助Matlab软件提供的FIR滤波器设计函数或FDATool软件,实现FIR带通滤波器设计,求得单位脉冲响应h(n).把h(n)代入Matlab函数tf2sos,求得FIR级联型网络结构的系数矩阵SOS和增益G.通过计算h(n)和输入序列x(n)的线性卷积,求得FIR滤波器的输... 借助Matlab软件提供的FIR滤波器设计函数或FDATool软件,实现FIR带通滤波器设计,求得单位脉冲响应h(n).把h(n)代入Matlab函数tf2sos,求得FIR级联型网络结构的系数矩阵SOS和增益G.通过计算h(n)和输入序列x(n)的线性卷积,求得FIR滤波器的输出y(n),提出了实现FIR数字滤波的线性卷积计算方法.根据FIR带通滤波器的边界截止频率,设计了输入序列x(n).借助CCS 5.5软件,采用C语言编程,设计了FIR直接型网络结构和FIR级联型网络结构的滤波程序,实现对输入序列x(n)滤波.实验结果表明,采用Matlab和CCS 5.5软件,能够很好地完成FIR数字带通滤波器实验设计. 展开更多
关键词 MATLAB软件 FDATool软件 CCS 5.5软件 FIR带通滤波器
在线阅读 下载PDF
无人机任务载荷运行环境实时监测系统设计 被引量:1
12
作者 李毅松 王代华 《仪表技术与传感器》 北大核心 2025年第6期117-121,共5页
针对当前无人机机载数据采集系统占用带宽过大,地面难以实现对机上状态实时监控的问题,设计了一种基于FPGA的无人机机上环境参数实时监测系统。系统采用三轴振动传感器和高精度ADC完成振动信号的采集和本地存储。通过在硬件上实现的FIR... 针对当前无人机机载数据采集系统占用带宽过大,地面难以实现对机上状态实时监控的问题,设计了一种基于FPGA的无人机机上环境参数实时监测系统。系统采用三轴振动传感器和高精度ADC完成振动信号的采集和本地存储。通过在硬件上实现的FIR与FFT算法,完成对采集信号的关键参数提取。仅将提取参数通过地空链路回传地面控制站,在占用极少带宽的情况下,实现对机上运行环境的实时监测。经振动试验验证:该系统能够实时采集、分析、处理振动信号,满足对无人机任务载荷运行环境的低带宽实时监测需求。 展开更多
关键词 机载 监测系统 振动信号 FIR FFT FPGA
在线阅读 下载PDF
一种平顶方向图宽带时域波束形成器设计方法 被引量:1
13
作者 王琦 张伟 +2 位作者 王建 王正浩 陈昳霏 《电子信息对抗技术》 2025年第2期80-84,共5页
针对平顶方向图宽带时域波束形成器的设计问题,将设计过程分解为频域平顶波束设计和时域波束有限冲激响应(Finite Impulse Response,FIR)滤波器计算两部分。构造加权向量和频域平顶波束方向图的变换关系,通过自适应调整旁瓣约束区域,快... 针对平顶方向图宽带时域波束形成器的设计问题,将设计过程分解为频域平顶波束设计和时域波束有限冲激响应(Finite Impulse Response,FIR)滤波器计算两部分。构造加权向量和频域平顶波束方向图的变换关系,通过自适应调整旁瓣约束区域,快速迭代优化加权向量。结合调向加权向量和群延时构造通道期望频率响应,求解最小均方误差准则下通道FIR滤波器系数,二者组合实现平顶方向图宽带时域波束形成器。该方法无需借助凸优化工具,仿真验证了设计方法的有效性。 展开更多
关键词 平顶方向图 时域波束形成 FIR滤波器 宽带波束形成
在线阅读 下载PDF
基于能量传递模式温敏上转换NaSrGd(MoO_(4))_(3)荧光粉的合成与发光特性研究
14
作者 余甜甜 钟小英 +2 位作者 陈秋娟 林妹 莫福旺 《中国稀土学报》 北大核心 2025年第6期1189-1198,共10页
非接触式温度传感器的研发目前备受关注,而高灵敏度是其突破的难点。本文采用固相反应的方法合成了NaSrGd_(1-x)(MoO_(4))_(3):0.05Er^(3+),0.05Yb^(3+),xTm^(3+)上转换(UC)发光荧光粉,讨论了不同稀土离子掺杂及不同浓度对其发光性能的... 非接触式温度传感器的研发目前备受关注,而高灵敏度是其突破的难点。本文采用固相反应的方法合成了NaSrGd_(1-x)(MoO_(4))_(3):0.05Er^(3+),0.05Yb^(3+),xTm^(3+)上转换(UC)发光荧光粉,讨论了不同稀土离子掺杂及不同浓度对其发光性能的影响,并就其温敏特性进行了光温特性研究。结果表明,Yb^(3+),Er^(3+)和Tm^(3+)的掺杂对荧光粉的物相结构没有影响。Tm^(3+)的引入通过能量传递增强了Er^(3+)在530和551 nm处的发光强度,在发射光谱的可见光波段500~750 nm中,500~570 nm范围内的绿光发射强度最强,而在红外光区域,796~807 nm的红外发射强度是所有发射峰中最强的。通过研究上转换发射强度对泵浦功率的依赖关系,发现荧光粉中Er^(3+)离子的530和551 nm绿色发射及656和669 nm红光发射均是双光子过程。在273~573 K范围内,Er^(3+)在530,551,656和669 nm处的发射峰与温度有关。利用荧光强度比技术(FIR),针对三掺杂样品在的绿色发射(530,551 nm)进行了温度荧光测试,实现了可见光温度测量,在温度荧光发射光谱中,利用热耦合能级(TCEL)计算出最大相对灵敏度(S_(r-max))为0.012%·K^(-1)(@273 K),最大灵敏度(S_(a-max))为0.39%·K^(-1)(@573 K),表明NaSrGd_(1-x)(MoO_(4))_(3):0.05Yb^(3+),0.05Er^(3+),xTm^(3+)荧光粉为一种良好耐高温的发光材料,能够应用于光学温度测量。 展开更多
关键词 能量传递 上转换发光 FIR 钼酸盐 稀土
原文传递
基于改进的迭代重加权OMP的稀疏FIR滤波器设计 被引量:1
15
作者 李怡 赵加祥 《电子信息对抗技术》 2025年第1期73-78,共6页
有限脉冲响应(Finite Impulse Response, FIR)滤波器具备线性相位和稳定性的优点,在雷达信号处理、图像处理、电子对抗等领域被广泛应用。然而高性能的FIR滤波器通常需要较高的阶数,导致硬件实现成本高、系统功耗大。针对该问题,提出了... 有限脉冲响应(Finite Impulse Response, FIR)滤波器具备线性相位和稳定性的优点,在雷达信号处理、图像处理、电子对抗等领域被广泛应用。然而高性能的FIR滤波器通常需要较高的阶数,导致硬件实现成本高、系统功耗大。针对该问题,提出了一种改进的迭代重加权正交匹配追踪算法,设计稀疏的线性相位FIR滤波器。该算法采用Frobenius范数简化在每次迭代中求解目标稀疏FIR滤波器的过程,并且引入一个对数函数迭代更新权重。仿真结果表明,在某些情况下所提算法设计的滤波器比已有的稀疏滤波器设计方法具有更短的有效滤波器长度和更少的滤波器非零抽头个数,避免了硬件实现时乘法器和加法器的大量使用,从而有效地降低了实现成本和系统功耗。 展开更多
关键词 稀疏FIR滤波器 线性相位 正交匹配追踪 FROBENIUS范数
在线阅读 下载PDF
基于迭代傅里叶变换的恒定束宽时域波束形成器设计
16
作者 王琦 张伟 +2 位作者 王建 王正浩 张航 《电子信息对抗技术》 2025年第3期60-64,共5页
为了解决宽带信号通过波束形成后易产生波形失真导致目标检测性能下降的问题,提出基于迭代傅里叶变换的恒定束宽时域波束形成器设计方法。该方法通过傅里叶变换建立加权系数与波束方向图的转换关系,迭代计算赋形恒定束宽频域波束加权系... 为了解决宽带信号通过波束形成后易产生波形失真导致目标检测性能下降的问题,提出基于迭代傅里叶变换的恒定束宽时域波束形成器设计方法。该方法通过傅里叶变换建立加权系数与波束方向图的转换关系,迭代计算赋形恒定束宽频域波束加权系数,然后在最小均方误差约束下转换为通道有限冲激响应(Finite Impulse Response,FIR)滤波器系数,二者结合实现时域波束形成器设计。给出了理论分析依据,仿真结果表明所提出的设计方法可实现宽带信号保真接收,同时具备灵活的宽带波束赋形、调向能力。 展开更多
关键词 傅里叶变换 恒定束宽 时域波束形成 FIR滤波器
在线阅读 下载PDF
基于BP神经网络的水声目标辐射噪声模拟方法
17
作者 薛婷 段文海 +1 位作者 邓磊磊 罗金旺 《舰船科学技术》 北大核心 2025年第11期122-126,共5页
针对水声目标辐射噪声仿真模拟的应用需求,本文对水声目标辐射噪声模拟方法进行研究,提出一种基于BP神经网络的噪声模拟方法。该方法首先采用基于变学习率的BP神经网络方法实现FIR滤波器设计,再将高斯噪声通过该FIR滤波器,得到特定频率... 针对水声目标辐射噪声仿真模拟的应用需求,本文对水声目标辐射噪声模拟方法进行研究,提出一种基于BP神经网络的噪声模拟方法。该方法首先采用基于变学习率的BP神经网络方法实现FIR滤波器设计,再将高斯噪声通过该FIR滤波器,得到特定频率响应的宽带连续谱噪声。最后连续谱叠加线谱和调制谱信号,得到辐射噪声仿真结果。通过对模拟的辐射噪声进行特征分析,使用方法能根据设定的频谱参数拟合水声目标辐射噪声的声学特征,以达到对不同频谱参数水声目标进行辐射噪声模拟仿真的目的。 展开更多
关键词 BP神经网络 辐射噪声 水声目标 FIR滤波器
在线阅读 下载PDF
神经网络拟合的激光陀螺惯组重力实时测量滤波
18
作者 高春峰 程嘉奕 +6 位作者 陈迈伦 魏国 罗晖 侯承志 朱旭 马海阳 王景 《国防科技大学学报》 北大核心 2025年第5期70-77,共8页
为了解决激光陀螺惯组重力测量系统中传统重力滤波方法的固定长时延问题,提出一种基于神经网络拟合滤波的重力数据实时处理方法,通过对有限长单位冲激响应(finite impulse response,FIR)滤波器进行神经网络拟合,降低对未来数据的长依赖... 为了解决激光陀螺惯组重力测量系统中传统重力滤波方法的固定长时延问题,提出一种基于神经网络拟合滤波的重力数据实时处理方法,通过对有限长单位冲激响应(finite impulse response,FIR)滤波器进行神经网络拟合,降低对未来数据的长依赖,从而有效减少滤波时延。实验结果表明,与FIR滤波器相比,该方法的处理时延降低了93%,平均滤波精度优于2 mGal,表明所提方法在保持较高精度的同时显著提升了数据处理的实时性,为激光陀螺惯组重力测量系统的实时重力测量提供了解决方案。 展开更多
关键词 重力测量 神经网络 FIR低通滤波 实时处理 重力数据处理
在线阅读 下载PDF
土压平衡盾构渣土改良中泡沫最佳注射比及其对土壤切向粘结强度影响研究 被引量:2
19
作者 于宇宇 《市政技术》 2025年第5期185-190,198,共7页
土压平衡盾构机在软土地层隧道施工中,土体改良作为关键工艺环节,对掌子面稳定性和设备工作性能具有双重调控的作用。而泡沫作为独立的土壤改良剂,其能促进土壤流化,形成均匀的土膏,进而降低土壤的渗透性、扭矩和黏性,同时还可以减少盾... 土压平衡盾构机在软土地层隧道施工中,土体改良作为关键工艺环节,对掌子面稳定性和设备工作性能具有双重调控的作用。而泡沫作为独立的土壤改良剂,其能促进土壤流化,形成均匀的土膏,进而降低土壤的渗透性、扭矩和黏性,同时还可以减少盾构刀盘的磨损,适用于多种类型的土壤改良。通过3个阶段的试验工作,优化泡沫注射比(Foam Injection Ratio,FIR)来确定泡沫的最佳使用量。试验结果表明:根据土壤的塑性指数可以确定低塑性土、中等塑性土和高塑性土的FIR范围;综合考虑土壤的塑性指数和含水量,泡沫对松软土壤的改良效果较差,而在硬度较高的土壤中则表现出了良好的改良效果;通过切向黏附试验确定了稠度指数为0.50~0.75的土样最佳FIR为20%~30%,稠度指数为0.75~1.00的土样最佳FIR为30%~50%,稠度指数为1.00~1.25的土样最佳FIR为50%~80%。 展开更多
关键词 隧道施工 土压平衡盾构 土体改良 FIR 粘结强度
在线阅读 下载PDF
上一页 1 2 130 下一页 到第
使用帮助 返回顶部