Noncovalent Functionalized Graphene-Filled Polyimides with Improved Thermal,Mechanical, and Wear Resistance Properties

A facile method is proposed to prepare poly-o-phenylenediamine (PoPD) noncovalent functionalized graphene (G)-reinforced polyimide (PI) nanocomposites. PoPD-G exhibited excellent dispersibility in various organic solvents. The structures of PoPD-G were characterized by Raman and UV spectrum, which verified the π–π interactions between PoPD and G. The effective exfoliation of graphene nanosheets was investigated by observation of the morphology of PoPD-G with SEM, SPM, and TEM. Compared to PI/G composites, the interfacial adhesion between graphene nanosheets and PI matrices promoted efficient stress transfer from PI chains to PoPD-G nanofillers. Polyimide nanocomposites with different incorporations of PoPD-G exhibited outstanding thermal properties. It is interesting to note that only 0.5 wt% PoPD-G-reinforced PI composites increased by 20.8% in hardness, enhanced by 84.0% in storage modulus, and reduced by 72.8% in wear rate compared with neat PI. The eminent enhancement was attributed to the facile dispersion of graphene nanosheets and strong interface adhesion between PI and PoPD-G.     

不同本构模型下建筑荷载对近邻地铁的沉降影响分析

针对高层建筑施工对近邻地铁隧道产生的影响,采用MC模型及CY模型两种土体本构模型,预测分析新建高层建筑荷载对紧邻地铁区间隧道及周边地表的沉降影响。结果显示,在计算参数均相同的条件下,两种本构模型得到的建筑荷载对周边土体的影响范围是一致的,但是该影响范围内的地表及隧道结构竖向沉降差异较大;根据工程经验,认为CY模型更符合真实情况。     

Super-Planckian thermal radiation enabled by hyperbolic surface phonon polaritons

Excitation of surface resonance modes and presence of resonance-free hyperbolic modes are two common ways to enhance the near-field radiative energy transport, which can find wide applications in noncontact thermal management and energy harvesting. Here, we identify another way to achieve the super-Planckian thermal radiation via hyperbolic surface phonon polaritons (HSPhPs). Based on the fluctuation-dissipation theory, the near-field radiative heat flux between bulk hexagonal boron nitride (hBN) planes with the optical axis perpendicular to the radiative energy flow can be 120 times as large as the blackbody limit for a gap distance of 20 nm. When the film thickness is reduced to 10 nm, the radiative heat flux is found to increase by 26.3%. The underlying mechanism is attributed to the coupling of Type I HSPhPs inside the anisotropic hBN film, which improves the energy transmission coefficient over a broad wavevector space especially for waves with extremely high wavevectors. This work helps to deepen the understanding of near-field radiation between natural hyperbolic materials, and opens a new route to enhance the near-field thermal radiation.     

High-speed photographic observation of collapse of two cavitation bubbles

Cavitation as a hydrodynamic phenomenon exists widely in water conservancy, shipbuilding, chemical and many other industries. Previous cavitation bubble dynamic studies mainly focused on single cavitation bubbles and their interaction with the wall. This paper studies the interaction between two cavitation bubbles under conditions with or without a wall. The results show that if the inception of two cavitation bubbles is not synchronized, the cavitation bubble of early inception collapse backwards the cavitation bubble of later inception; if the inception of two cavitation bubbles is synchronized, the two bubbles collapse towards each other; if a wall exists nearby, no matter whether the line connecting the centers of the two cavitation bubbles is vertical or parallel to the wall, the two cavitation bubbles collapse towards each other and then gradually merge, and the merged collapse body quickly moves to the wall. It is suggested that, as the number of cavitation bubbles increases, the cavitation erosion effect is not simply increased proportionally. Instead, mutual inhibitory effect may be demonstrated.     

Kinetic theory for aquatic animal distribution simulation

Identifying the underlying mechanisms that influence the spatial patterns in populations improves the forecasts of the alternative management strategies on the spatial dynamics of the populations, which are critical for assessing and managing the fisheries and improving the water resource management. This paper described a new approach of the numerical model for the prediction of the aquatic animal distribution in the flows. The model was developed based on the kinetic theory of gases, the mechanism of the aquatic animal movement and the flow hydrodynamic patterns. The model was validated using the available experimental data and an acceptable agreement was obtained. A comprehensive parameter study was then conducted to help understand the impact and the sensitivity of each parameter to the aquatic animal distribution. The promising results of the model reveal the prospect of applying this model to the reliable prediction of the aquatic animal distribution within a relatively large water area.     

基于下肢动力学检测分析的站起康复训练机器人控制

提出了人体站起轨迹控制方法(TCM)和阻尼控制方法(ICM)。采用这两种控制方法可以实现对机器人系统的控制,使患者能安全、有效地进行下肢站起运动康复训练。在患者站起过程中,下肢各肢段旋转角、身体运动轨迹、地面反力(GRF)、压力中心(COP)和绳索张力等参数可由康复机器人系统中的相应传感器实时检测得出,并通过实时运算得出髋、膝、踝各关节力矩,用于反馈控制。试验结果表明,该方法可以保证患者实现安全、舒适、有效的站起训练,适用于站起康复训练机器人控制系统。     

传统刺绣工艺在现代服装设计中的时尚化体现

对传统刺绣在当代时尚社会的发展进行了初步的研究,从刺绣本身的材质、图案题材、针法到刺绣工艺手法的结合创新,进行了分析,总结出传统刺绣的时尚性演变与发展,旨在对现有的刺绣情况进行总结,丰富设计手法,将传统刺绣的继承与发展落到实处。     

综合物探方法在乌林镇地热勘查中的应用

利用瞬变电磁、电测深、地温测量等方法,在湖北省洪湖市地热资源勘查中划分地层、构造,探测含水裂隙带.对资料进行综合分析,初步确定了地热田的分布情况,探明了导热断裂、储热断裂及热储层,并分析了地热流体的化学成分,为综合利用开发该地地热资源提供了规划依据.     

利用DXF格式实现GeoTIFF图像在AutoCAD中的自动配准

在AutoCAD中手动插入带有地理坐标的网片效率低,定位精度差.本文以GeoTIFF图像为例,提出了一种利用DXF格式,在脱离AutoCAD环境下,将带坐标信息的图片按实际坐标准确、快速插入到AutoCAD中的方法.实现过程是:先编程提取GeoTIFF图像的关键信息,然后利用DXF格式引用外部图像的存储规则,通过将GeoTIFF图像的路径、角点坐标、像素分辨率等参数写入相应组值,实现图像在AutoCAD中的自动插入与坐标精确配准.实践表明,该方法不仅可实现GeoTIFF格式图像的批量插入,亦可推广到其它附带坐标信息的栅格图像,且具有实现过程简单,运行高效的特点.     

Dynamic observation of bainite transformation in a Fe-C-Mn-Si superbainite steel

The dynamic observations of bainitic transformation in a Fe-C-Mn-Si superbainite steel were conducted on a high temperature laser scanning confocal microscope. It is indicated that the mutual intersection of bainite sheaves often occurs during growth of bainite ferrite, resulting in an interlocked bainite microstructure. Moreover, bainite transformation is promoted by higher austenization temperature and the longer and finer bainite platelets are obtained. Further, The average growth rate of bainite after austenization at 1 100 ° is calculated as 5.8 µm·s^?1. In situ observation investigation makes it possible to identify bainite transformation in real time during isothermal holding.