冷轧薄宽带钢局部型中浪瓢曲变形行为研究

针对薄宽带钢冷轧过程中易发多发的局部型中浪瓢曲缺陷,引入非均匀载荷宽度、弹性约束系数及平均张应力建立了屈曲变形的解析计算模型。应用能量最低原理对屈曲变形区域进行搜索求解,得到了局部型中浪屈曲临界条件(包括临界应力、屈曲波长和屈曲波宽),获得了其与非均匀载荷宽度、弹性约束系数、平均张应力的关系,并发现平均张应力是产生局部型中浪的重要影响因素。应用样条有限元方法对局部型中浪进行数值仿真分析,验证了屈曲解析计算方法的正确性。在实验轧机上进行了轧制研究,通过轧制获得了局部型中浪屈曲模态,对实验结果分析得到了相对应的屈曲临界条件,与解析法和样条有限元法结果基本吻合,证明了样条有限元计算方法与解析计算方法的正确性及其工程应用价值。     

INFLUENCE OF DAMPING MODELS ON DYNAMIC ANALYSES OF A BASE-ISOLATED COMPOSITE STRUCTURE UNDER EARTHQUAKES AND ENVIRONMENTAL VIBRATIONS

Structural design simultaneously governed by earthquakes and environmental vibrations has received a lot of attention in recent years.Base-isolated composite structures are typically used in the above-mentioned structural design.The corresponding analysis involves validating structural safety under earthquakes and human comfort under environmental vibrations through a time-history analysis.Thus,a reasonable damping model is essential.In this work,the representatives of viscous damping model and rate-independent damping model,namely the Rayleigh damping model and uniform damping model,were adopted to investigate the influence of damping models on the time-history analysis of such structural designs.The energy dissipation characteristics of the above-mentioned damping models were illustrated via a dynamic test of recycled aggregate concrete specimens.A case study was performed on a base-isolated steelconcrete composite structure.The dynamic responses under the excitation of earthquakes and environmental vibrations were compared using different damping models.The uniform damping model was found to be more flexible than the Rayleigh damping model in dealing with excitations with different frequency components.The uniform damping model is both theoretically advantageous and easy to use,demonstrating its potential in dynamic analysis of structures designed simultaneously governed by earthquakes and environmental vibrations.     

A VIBRATION RECOGNITION METHOD BASED ON DEEP LEARNING AND SIGNAL PROCESSING

Effective vibration recognition can improve the performance of vibration control and structural damage detection and is in high demand for signal processing and advanced classification.Signal-processing methods can extract the potent time-frequency-domain characteristics of signals;however,the performance of conventional characteristics-based classification needs to be improved.Widely used deep learning algorithms(e.g.,convolutional neural networks(CNNs))can conduct classification by extracting high-dimensional data features,with outstanding performance.Hence,combining the advantages of signal processing and deep-learning algorithms can significantly enhance vibration recognition performance.A novel vibration recognition method based on signal processing and deep neural networks is proposed herein.First,environmental vibration signals are collected;then,signal processing is conducted to obtain the coefficient matrices of the time-frequency-domain characteristics using three typical algorithms:the wavelet transform,Hilbert-Huang transform,and Mel frequency cepstral coefficient extraction method.Subsequently,CNNs,long short-term memory(LSTM)networks,and combined deep CNN-LSTM networks are trained for vibration recognition,according to the time-frequencydomain characteristics.Finally,the performance of the trained deep neural networks is evaluated and validated.The results confirm the effectiveness of the proposed vibration recognition method combining signal preprocessing and deep learning.     

数字3D电影最新动向

全球数字3D电影领域的领头羊Real D公司于10月17日与欧洲投资商Terra Firma公司旗下在泛西欧拥有1600块银幕的Odeon院线以及UCI院线签署协议,将于未来2年中在英国、爱尔兰、德国、奥地利以及葡萄牙合作安装500块数字3D银幕.     

第十二届中国建筑企业高峰论坛在绍兴市举行王治安主持会议并致辞

<正>本刊讯2014年12月23日,由中国建设报社、浙江省住房和城乡建设厅、绍兴市人民政府主办的第十二届中国建筑企业高峰论坛在绍兴市举行。来自全国各地的建筑行业主管部门、行业协会负责人,专家学者及企业代表等300余人齐聚一堂,围绕"创新融合,开放共赢"主题,共同分享了一场建筑行业思想盛宴。中国建设报社党委书记杜久才、社长翟建和中国建筑装饰协会会长李秉仁、中国土木工程协会副理事长刘     

9.3大阅兵:高标准让军魂荡气回肠

<正>阅兵是展示辉煌的时刻,而为这一辉煌采取的所有的标准,不啻也是宝贵的财富,应当成为践行标准的榜样……这个月最令人难忘、最引人自豪、最提振国威的事情,当属"9.3"大阅兵,它有着以往没有的多重的亮点:首次以纪念抗日战争暨世界反法西斯战争胜利为阅兵主题,彰显维护和平是全世界人民共同的愿望。首次邀请外国军队代表参加分列式,体现纪念大会的国际性。首次组织抗战老兵包括国民党老兵参加,体现了对历史的尊重,体现全民族抗战的特色。首次编组英模部队方队受阅,展示中国共产党在抗战中定海     

车类影视广告拍摄——光线表现篇

汽车能满足人们生活、娱乐、工作的各种需求,为生活添加乐趣.商务车、房车、越野车或轿车,不管是驰骋还是安静地停放,都具有他们独特的气质,外型、轮廓、结构、颜色、车漆的纹理及其光泽度各有特点.拍摄广告就是要把汽车的这些独到之处提炼、表达出来,在观赏者印象中建立一个全方位的立体形象,激发消费者的购买愿望,这里就必须用到一个非凡的摄影手段--光线.     

CIG前驱膜叠层方式对CIGS膜成分和结构的影响

采用中频交流磁控溅射方法制备了三种不同叠层方式的CuInGa（CIG）前驱膜。采用固态法硒化,获得了CIGS吸收层。采用SEM和XRD观察和分析了薄膜的成分、组织结构和表面形貌。着重分析不同叠层方式的CIG前驱膜对CIGs吸收层薄膜成分、晶体结构的影响。结果表明,三种叠层方式的前驱膜都可以获得成分均匀、结构一致的CIGS吸收层薄膜。Ga可以有效抑制In2Se挥发相生成,保持成分的稳定性。以CuGa（top）／CuIn（bottom）形式的前驱膜有利于形成紧密晶粒排列的CIGS。     

Control of vertical phase separation in high performance non-fullerene organic solar cell by introducing oscillating stratification preprocessing

Non-fullerene organic solar cell(NFOSC)has attracted tremendous attention due to their great potential for commercial applications.To improve its power conversion efficiency(PCE),generally,sequential solution deposition(SSD)methods have been employed to construct the graded vertical phase separation(VPS)of the bulk-heterojunction(BHJ)active layer for efficient exciton separation and charge transition.However,a variety of orthogonal solvents used in the SSD may lead to the unpredicted change in the BHJ morphology and introduce additional defects inside the BHJ bulk thus complicate the fabrication process.Here,a simple oscillating stratification preprocessing(OSP)is developed to facilitate the formation of graded VPS among the BHJ layer.As a result,a significant improvement is obtained in PCE from 10.96%to 12.03%,which is the highest value reported among PBDB-T:ITIC based NFOSC.     

High power and stable P-doped yolk-shell structured Si@C anode simultaneously enhancing conductivity and Li+ diffusion kinetics

Silicon is a low price and high capacity ancxje material for lithium-ion batteries.The yolk-shell structure can effectively accommodate Si expansion to improve stability.However,the limited rate performance of Si anodes can't meet people's growing demand for high power density.Herein,the phosphorus-doped yolk-shell Si@C materials(P-doped Si@C)were prepared through carbon coating on P-doped Si/SiO_xmatrix to obtain high power and stable devices.Therefore,the as-prepared P-doped Si@C electrodes delivered a rapid increase in Coulombic efficiency from 74.4%to 99.6%after only 6 cycles,high capacity retention of-95%over 800 cycles at 4 A·g^-1,and great rate capability(510 mAh·g^-1at 35 A·g^-1).As a result,P-doped Si@C anodes paired with commercial activated carbon and LiFePO₄cathode to assemble lithium-ion capacitor(high power density of?61,080 W·kg^-1at 20 A·g^-1)and lithium-ion full cell(good rate performance with 68.3 mAh·g^-1at 5 C),respectively.This work can provide an effective way tofurther improve power density and stability for energy storage devices.     

高速移动列车荷载作用下层状饱和地基-轨道耦合系统的动力响应

基于Biot流体饱和多孔介质理论,求得层状饱和地基表面移动荷载的动力格林函数,进而建立2.5维间接边界元方法,研究了高速移动列车荷载作用下层状饱和地基-轨道耦合系统的动力响应。该文通过与已有结果的比较验证了方法的正确性,并以均匀饱和半空间地基和饱和基岩上单一饱和土层地基为模型进行了数值计算,分析了列车移动速度和饱和土层等对动力响应的影响。研究表明,层状饱和地基和均匀饱和地基对应的动力响应有着显著的差别;列车移动速度接近饱和地基的Rayleigh波速时,会引起饱和地基-轨道耦合系统的共振,产生较大的动力响应;饱和地基不透水情况下动力响应最大,饱和地基透水情况下动力响应次之,干土情况下动力响应最小。另外,饱和土孔隙率、饱和基岩与饱和土层刚度比、饱和土层厚度等也对动力响应具有重要影响。     

饱和弹性半空间地基与中厚圆板的动力相互作用

利用Fourier-Bessel级数,对横观各向同性饱和弹性半空间地基与中厚圆板的动力相互作用问题进行了系统地分析。板的位移函数、荷载、地基反力及板下地基表面的沉降均被展开为二重Fourier-Bessel级数,这些级数中的待定系数由板的边界条件、板的控制方程及板-地基的相容条件加以确定,从而将饱和弹性半空间地基与中厚圆板的动力相互作用问题转化为数值积分和代数方程组的求解问题。数值计算表明,该级数解答具有较快的收敛速度。可以将该方法推广到弹性半空间与梁、矩形板相互作用问题的分析。     

层状饱和半空间中沉积谷地对斜入射平面P1波的三维散射

在作者给出层状饱和场地三维精确动力刚度矩阵和层状饱和半空间中移动荷载动力格林函数基础上,采用间接边界元方法在频域内求解了层状流体饱和场地中沉积谷地对斜入射平面P1波的三维散射问题。该方法的特点在于虚拟移动均布荷载和斜线孔隙水压可以直接施加在沉积与层状饱和半空间交界面而不存在奇异性。该文通过与已有结果的比较验证了方法的正确性,并以均匀饱和半空间和弹性基岩上单一饱和土层中沉积谷地为例进行了数值计算分析。研究表明,沉积谷地对平面P1波的三维散射与二维散射之间存在本质差别,入射角度、孔隙率、饱和土层刚度和饱和土层厚度等参数对沉积谷地附近动力响应有着显著影响。     

局部褶皱对层状地基马蹄形孔洞散射的影响分析

水平岩层在构造作用下会产生局部褶皱,研究褶皱对层状地基马蹄形孔洞散射的影响,对地表结构地震安全性评价具有重要意义。基于子结构法建立了复杂场地散射问题的控制方程,将地震波散射问题的求解转化具有规则边界条件的层状地基(自由场)的动力刚度和波动响应的求解。通过Fourier变换和引入对偶变量,将波动方程转化为一阶常微分方程,采用精细积分算法对土层可实现高效合并,施加边界条件可得到内部节点的格林函数,进一步得到动力刚度。同时,采用精细积分算法代替原传递矩阵法的层间合并,可得到层状自由场的波动响应。这种改进传递矩阵法对土层厚度和层数没有任何限制。通过与文献中的结果对比,验证了方法的正确性,并分析了局部褶皱对层状地基中马蹄形孔洞散射场的影响。结果表明:局部褶皱对地表位移幅值的影响与入射波类型、入射波频率以及局部褶皱几何构造等因素均有关系;地表位移峰值受马蹄形孔洞和局部褶皱共同作用的影响,其影响特性与入射波类型无明显关系。     

层状饱和场地中线性分布斜线荷载的动力Green函数

基于一种实用的Bo it模型,利用层状饱和土层的精确动力刚度矩阵,给出了层状饱和场地中线性分布荷载作用于与水平向有夹角的倾斜直线时的动力G reen函数,解决了利用间接边界元法分析局部地形对地震波散射及土-结构动力相互作用等研究中的关键问题。本文解答可以退化为W o lf弹性情况结果,最后进行了算例分析。     

基于TI介质模型的凸起地形对平面SH波的放大作用

在模拟地震波在介质中传播过程的研究中,正演模拟是一个重要的方面。该文采用间接边界元法（IBEM）对横观各向同性（TI）不同参数介质的凸起场地中入射SH波的散射问题进行了正演模拟,研究了TI凸起场地对SH波的放大效应。放大效应是通过地表位移与基岩露头位移幅值的比值来体现的。该间接边界元法结合了层状TI半空间精确动力刚度矩阵和均布斜线荷载动力格林函数,具有较高的精度。该文分别给出了TI介质凸起中SH波散射问题在频域和时域内的解答。频域内研究分析表明,土体TI介质参数的变化会对场地位移幅值的放大谱和空间分布产生显著的影响,即改变了凸起部分和土层的动力特性,使得两者动力相互作用发生改变。时域内研究表明,SH波在凸起周围的传播同时依赖于TI介质参数的具体取值和传播方向。时域位移幅值云图清晰地展示入射波、透射波、反射波和散射波的传播过程,凸起角点产生的散射波在TI介质中传播呈现\     

Dynamic responses of a pile embedded in a layered poroelastic half-space to a harmonic axial loading

The dynamic response of a single pile embedded in a layered poroelastic half-space to an axial harmonic load is investigated in this study. Based on Biot’s theory, the frequency domain fundamental solution for a vertical circular patch load applied in a layered poroelastic half-space is derived via the transmission and reflection matrices method. Utilizing Muki and Sternberg’s method, the second kind of Fredholm integral equations describing the dynamic interaction between the layered half-space and the pile subjected to a harmonic axial load is constructed. The proposed model is validated by comparing a special case of our model with an existing result. Based on numerical results of this paper, it is concluded that the presence of a stiffer or a softer middle layer in the layered half-space will affect the impedance of the pile considerably and the inhomogeneity of the half-space will enhance the pore pressure significantly.     

移动随机线源荷载作用下黏弹性半空间体的动力响应

求解移动荷载作用下黏弹性半空间体的响应,是研究交通荷载引起的环境振动问题的基础。移动荷载作用下半空间体响应的积分形式解不难得出,但当荷载移动速度接近或大于瑞利波速时,被积函数往往具有奇异性和高振荡性,这就使得数值计算相当困难。该文研究了移动随机线源荷载作用下黏弹性半空间体的响应问题。利用虚拟激励法,将系统的随机振动分析转化为确定性分析,然后通过广义Duhamel积分得到了响应的积分形式解。将被积函数图形化确定了函数的积分限,通过自适应数值积分算法解决了被积函数的振荡性,最终得出了黏弹性半空间体动力响应的数值结果。为确保数值计算结果的正确性,同样计算了确定性荷载作用下半空间体的响应,并与已有文献结果进行了对比。在验证了数值算法正确性的基础上,计算了随机荷载作用下半空间体的响应,荷载移动速度涵盖了亚音速、跨音速和超音速三种情形。通过具体算例,分析了响应的时间和空间分布规律,并对荷载移动速度对响应的影响进行了分析。     

遮挡山体对输电塔线体系风振疲劳的影响

山地地形中遮挡山体使风场更加复杂,对结构的风致响应也造成了较大影响。为此,本文首先基于风洞试验研究了遮挡山体的不同坡度、高度以及间距对受扰山体风场特性的影响,通过对13种工况中受扰山体的山顶和背风面加速比的变化情况进行分析,得到了遮挡山体对风场的影响规律。然后,根据风向风速实测数据计算出风向风速联合分布的统计概率,结合时域和频域疲劳累积损伤理论,提出了输电塔线体系风振疲劳的建议算法。最后,基于试验数据及统计概率对某特高压输电塔线体系在各工况的风场条件下分别进行了风振疲劳分析,结果表明：输电塔疲劳寿命随遮挡山体坡度呈先增后减的复杂变化趋势,山体背风面山脚疲劳寿命最短;坡度相同而高度不同的遮挡山体未对输电塔疲劳寿命造成明显变化;遮挡山体间距较小时输电塔疲劳寿命最短,但随着遮挡间距增加受扰山体风场逐渐趋于稳定,疲劳寿命随之延长。     

成层液化场地条件下单桩振动分析

将层状土中桩基振动相关理论扩展应用到考虑土层液化的桩基振动的研究,借助于Winkler弹簧-阻尼器模型描述液化土和非液化土与桩基之间的动力相互作用,利用初参法和传递矩阵法得到了地震激励作用下考虑土层液化的桩基桩顶位移放大因子。结果表明,液化后的土层软化系数、土层厚度、桩身抗弯刚度和桩身线质量密度等对考虑液化的桩基振动特性有较大的影响。