检索结果-南通市图书馆

Diffraction of plane P waves by a canyon of arbitrary shape in poroelastic half-space (Ⅱ): Numerical results and discussion

在线全文

学校读者我要写书评

暂无评论

Earthquake Science 2009年第3期22卷 223-230页

作者： jianwen liang zhongxian liu Department of Civil Engineering Tianjin University Tianjin 300072 China

This paper investigates in detail the nature of diffraction of plane P waves around a canyon in poroelastic half-space, and studies the effects of incident frequency, drainage condition, porosity, etc, on the diffraction of waves. It is shown that the surface displacement amplitudes of the drained case are close to those of the undrained case, however, the surface displacement amplitudes of the dry case are very different from those of the saturated （either drained or undrained） cases. There are large phase shift between the dry case and the saturated cases, as well as slightly longer resultant wavelengths for the undrained case than those for the drained case and longer resultant wavelengths for the drained case than those for the dry case. For small porosity the surface displacement amplitudes for the saturated cases are almost identical to those for the dry case; while for large porosity, the effect of drainage condition becomes significant, and the surface displacement amplitudes for the undrained case are larger than those for the drained case. As the incident frequency increases, the effect of porosity becomes significant, and more significant for the undrained case than that for the drained case. As the porosity increases, the pore pressures increase significantly but their oscillations become smoother. As the incident frequency increases, the pore pressures become more complicated.

关键词： poroelastic half-space canyon diffraction plane P wave surface displacement pore pressure

同方期刊数据库

Scattering of seismic waves by three-dimensional large-scale hill topography simulated by a fast parallel IBEM

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2020年第4期19卷 855-873页

作者： liu zhongxian Shang Ce Huang Lei liang jianwen Li Jie Tianjin Key Laboratory of civil structure protection and reinforcing Tianjin Chengjian UniversityTianjin 300384China PC Research and Development Centre Tianjin Architecture Appraisal&Design InstituteTianjin 300072China Department of Civil Engineering Tianjin UniversityTianjin 300072China

To solve seismic wave scattering by a large-scale three-dimensional(3-D) hill topography, a fast parallel indirect boundary element method(IBEM) is developed by proposing a new construction method for the wave field, modifying the generalized minimum residual(GMRES) algorithm and constructing an Open MP plus MPI parallel model. The validations of accuracy and efficiency show that this method can solve 3-D seismic response of a large-scale hill topography for broadband waves, and overcome the weakness of large storage and low efficiency of the traditional IBEM. Based on this new algorithm architecture, taking the broadband scattering of plane SV waves by a large-scale Gaussian-shaped hill of thousands-meters height as an example, the influence of several important parameters is investigated, including the incident frequency, the incident angle and the height-width and length-width ratio of the hill. The numerical results illustrate that the amplification effect on the ground motion by a near-hemispherical hill is more significant than the narrow hill. For low-frequency waves, the scattering effect of the higher hill is more pronounced, and there is only a single peak near the top of the hill. However, for high-frequency waves, rapid spatial variation of displacement amplitude appears on the hill surface.

关键词： scattering of seismic waves 3-D hill topography indirect boundary element method(IBEM) parallel calculation

Dynamic interaction of twin vertically overlapping lined tunnels in an elastic half space subjected to incident plane waves

在线全文

学校读者我要写书评

暂无评论

Earthquake Science 2016年第3期29卷 185-201页

作者： zhongxian liu Yirui Wang jianwen liang Tianjin Key laboratory of civil structure protection and reiforcement Tianjin Chengjian University Department of Civil Engineering Tianjin University

The scattering of plane harmonic P and SV waves by a pair of vertically overlapping lined tunnels buried in an elastic half space is solved using a semi-analytic indirect boundary integration equation method. Then the effect of the distance between the two tunnels, the stiffness and density of the lining material, and the incident frequency on the seismic response of the tunnels is investigated. Numerical results demonstrate that the dynamic interaction between the twin tunnels cannot be ignored and the lower tunnel has a significant shielding effect on the upper tunnel for high-frequency incident waves, resulting in great decrease of the dynamic hoop stress in the upper tunnel; for the low-frequency incident waves, in contrast, the lower tunnel can lead to amplification effect on the upper tunnel. It also reveals that the frequency-spectrum characteristics of dynamic stress of the lower tunnel are significantly different from those of the upper tunnel. In addition, for incident P waves in low-frequency region, the soft lining tunnels have significant amplification effect on the surface displacement amplitude, which is slightly larger than that of the corresponding single tunnel.

关键词： Vertically overlapping lined tunnels Scattering Indirect boundary integration equation method(IBIEM) Soil-tunnel dynamic interaction

Diffraction of plane SV waves by a cavity in poroelastic half-space

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2009年第1期8卷 29-46页

作者： liang jianwen and liu zhongxian Department of Civil Engineering, Tianjin University, Tianjin 300072, China Professor PhD Candidate Department of Civil Engineering Tianjin University Tianjin 300072 China

This paper presents an indirect boundary integration equation method for diffraction of plane SV waves by a 2-D cavity in a poroelastic *** Green＇s functions of compressive and shear wave sources are derived based on Biot＇s theory. The scattered waves are constructed using fictitious wave sources close to the boundary of the cavity, and their magnitudes are determined by the boundary conditions. Verification of the accuracy is performed by：（1） checking the satisfaction extent of the boundary conditions, （2） comparing the degenerated solutions of a single-phased case with well- known solutions, and （3） examining the numerical stability of the solutions. The nature of diffraction of plane SV waves around a cavity in a poroelastic half-space is investigated by numerical examples.

关键词： poroelastic half-space cavity diffraction plane SV waves compressive wave source shear wave source Green's function pore pressure

Large-area(64 × 64 array) inkjet-printed high-performance metal oxide bilayer heterojunction thin film transistors and n-metal-oxide-semiconductor(NMOS) inverters

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第22期81卷 26-35页

作者： Shuangshuang Shao Kun liang Xinxing Li Jinfeng Zhang Chuan liu Zheng Cui jianwen Zhao Printable Electronics Research Center Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesSuzhou215123China School of Engineering Westlake UniversityHangzhou310024China Zhejiang University Hangzhou310027China The Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology School of Electronics and Information TechnologySun Yat-sen UniversityGuangzhou510275China

It is a big challenge to construct large-scale,high-resolution and high-performance inkjet-printed metal oxide thin film transistor(TFT)arrays with independent gates for the new printed ***,a self-confined inkjet printing technology has been developed to construct large-area(64×64 array),high-resolution and high-performance metal oxide bilayer(In_(2)O_(3)/IGZO)heterojunction TFTs with independent bottom gates on transparent glass *** printing In_(2)O_(3) dot arrays with the diameters from 55 to 70μm and the thickness of~10 nm were firstly deposited on UV/ozone treated AlO_(x) dielectric layers,and then IGZO dots were selectively printed on the top of In_(2)O_(3) dots by self-confined technology to form In_(2)O_(3)/IGZO heterojunction *** the inkjet-printed IO layers treated by UV/ozone for more than 30 min or oxygen plasma for 5 min prior to print IGZO thin films,the mobility of the resulting printed In_(2)O_(3)/IGZO heterojunction TFTs are correspondingly enhanced to be 18.80 and 28.44 cm^(2) V^(-1) s^(-1) with excellent on/off ratios(>10^(8))and negligible ***,the printed N-Metal-Oxide-Semiconductor(NMOS)inverter consisted of an In_(2)O_(3)/IGZO TFT and an IGZO TFT has been demonstrated,which show excellent performance with the voltage gain up to *** strategy demonstrated here can be considered as general approaches to realize a new generation of high-performance printed logic gates,circuits and display driving circuits.

关键词： Inkjet printing Heterojunction channel 64×64 arrays High mobility NMOS inverter

Effects of drought stress on the photosynthetic physiological parameters of Populus 3 euramericana ‘‘Neva''

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2019年第2期30卷 409-416页

作者： Guoting liang jianwen Bu Shuyong Zhang Guo Jing Guangcan Zhang Xia liu Shandong Provincial Key Laboratory of Soil Erosion and Ecological Restoration Forestry College of Shandong Agricultural University Taishan Forest Eco-station of State Forestry Administration Department of Food Science and Engineering Shandong Agriculture and Engineering University Forestry College of Nanjing Forestry University

Populus 9 euramericana ‘‘Neva'' is the main poplar species in China, where drought stress is becoming extremely urgent. We carried out this research to study the effects of drought stress on the photosynthesis of Populus 9 euramericana ‘‘Neva''. Drought stress was induced by 58–62%(light), 48–52%(moderate), and 38–42%(severe) relative soil moisture content(RSMC). The effects of drought stress on photosynthetic rate, chlorophyll fluorescence parameters, and other related physiological parameters were investigated during treatment. Net photosynthetic rate(PN), and stomatal conductance decreased significantly and intercellular CO_2 concentration initially increased and then declined, whereas the stomatal limitation factors showed opposite trends in the light under moderate drought stress. Photosystem II(PSII) maximum photochemical efficiency, actual photochemical efficiency,and photochemical quenching decreased gradually under drought stress, whereas nonphotochemical quenching initially increased and then declined. Superoxide dismutase,peroxidase, and catalase activities initially increased and then decreased as RSMC was reduced, whereas malondialdehyde(MDA) content and relative electric conductivity(REC) increased gradually. These results suggest that stomatal factors accounted for the decline in PNunder light and moderate drought stress, whereas leaf PNdecreased mainly due to non-stomatal factors under severe drought stress. PSII was damaged; thus, photosynthetic electron transfer was restricted, indicating that heat dissipation is important for the light protection mechanism of *** enzymes increased at the beginning of treatment, and the increased MDA and REC led to cell membrane damage. These results suggest that poplar seedlings stabilized their photosynthetic apparatus by reducing the light trapping ability under light and moderate drought stress conditions. This helped dissipate heat and enhance antioxidant enzyme activity. Stomatal factors accoun

关键词： Poplar seedlings Drought stress Gas exchange Chlorophyll fluorescence Antioxidantenzymes

在线全文

学校读者我要写书评

暂无评论

弹性半空间中衬砌隧道对瑞利波的散射

岩石力学与工程学报 2011年第8期30卷 1627-1637页

作者：刘中宪梁建文张贺天津城市建设学院天津市软土特性与工程环境重点实验室天津300384 天津大学土木工程系天津300072

采用一种高精度的间接边界积分方程法,对弹性半空间中衬砌隧道对入射瑞利的二维散射问题进行求解分析。结果表明:衬砌隧道和非衬砌隧道对瑞利波的散射具有显著的差别,衬砌刚度对波的散射规律具有重要影响。隧道附近地表动力响应和隧道... 详细信息

采用一种高精度的间接边界积分方程法,对弹性半空间中衬砌隧道对入射瑞利的二维散射问题进行求解分析。结果表明:衬砌隧道和非衬砌隧道对瑞利波的散射具有显著的差别,衬砌刚度对波的散射规律具有重要影响。隧道附近地表动力响应和隧道衬砌动应力集中主要取决于衬砌和围岩的刚度比、隧道的埋深和直径、入射波频率等因素。对于柔性衬砌,浅埋隧道对低频瑞利波会产生显著的位移放大效应;对于刚性衬砌,衬砌内壁的动应力集中效应十分明显。整体上看,随着埋深的增大,隧道周围波的散射逐渐减弱。

关键词：隧道工程弹性半空间衬砌隧道间接边界积分方程法瑞利波散射

平面SV波在饱和半空间中沉积谷地周围的散射

在线全文

学校读者我要写书评

暂无评论

地震工程与工程振动 2010年第3期30卷 12-21页

作者：梁建文刘中宪天津大学土木工程系天津300072

采用一种特殊的间接边界积分方程法,求解了平面SV波在饱和半空间中任意形状沉积谷地周围的二维散射问题。结合饱和半空间中膨胀波源和剪切波源格林函数,由分布在沉积和半空间交界面附近两虚拟波源面上的波源分别构造沉积内外的散射波场... 详细信息

采用一种特殊的间接边界积分方程法,求解了平面SV波在饱和半空间中任意形状沉积谷地周围的二维散射问题。结合饱和半空间中膨胀波源和剪切波源格林函数,由分布在沉积和半空间交界面附近两虚拟波源面上的波源分别构造沉积内外的散射波场,由交界面连续条件建立方程并求解确定虚拟波源密度,总波场反应即可由自由波场和散射波场叠加而得。然后通过边界条件验算、退化解答与现有结果的比较以及稳定性检验,验证了方法的计算精度。通过一组典型算例,研究了平面SV波在饱和半空间中沉积谷地周围散射的基本规律,详细给出了不同参数情况沉积谷地附近地表位移幅值和孔隙水压,着重分析了入射SV波频率和角度、边界渗透条件、沉积孔隙率等因素对场地反应的影响,得出了一些有益的结论。

关键词：饱和半空间沉积谷地散射间接边界积分方程法平面SV波

三维粘弹性层状半空间埋置集中荷载动力格林函数求解-修正刚度矩阵法

在线全文

学校读者我要写书评

暂无评论

固体力学学报 2013年第6期34卷 579-589页

作者：刘中宪梁建文天津城建大学天津市软土特性与工程环境重点实验室天津300384 天津大学土木工程系天津300072

针对三维粘弹性层状半空间埋置集中荷载作用下动力响应计算,在柱面坐标下,结合径向Hankel和周向Fourier变换,提出了一种新的求解方法—修正刚度矩阵法.方法首先固定荷载所在层的上下界面,在空间波数域内,由波动方程的特解和齐解叠加得到... 详细信息

针对三维粘弹性层状半空间埋置集中荷载作用下动力响应计算,在柱面坐标下,结合径向Hankel和周向Fourier变换,提出了一种新的求解方法—修正刚度矩阵法.方法首先固定荷载所在层的上下界面,在空间波数域内,由波动方程的特解和齐解叠加得到"固端"反力.进而放松两"固端约束",利用直接刚度法容易求得各层面位移.荷载作用层内反应另需叠加上该"固定层"内解,其中特解部分积分由全空间解析解代替,由此解决了当接收点和源点作用水平面接近时异常积分收敛问题.算例分析表明,对于低频(可退化为静力状态)和高频问题,论文方法均具有很高的计算效率和精度.

关键词：格林函数粘弹性层状半空间动力集中荷载修正刚度矩阵法