Window Detection in Facades Using Heatmap Fusion

Journal of Computer Science and Technology - Window detection is a key component in many graphics and vision applications related to 3D city modeling and scene visualization. We present a novel...     

Fully transient analytical solution for degradable organic contaminant transport through GMB/GCL/AL composite liners

In this study, analytical solution for degradable organic contaminant transport through a composite liner consisting of a geomembrane (GMB) layer, a geosynthetic clay liner (GCL) and an attenuation layer (AL) is derived by the separation of variables method. The transient contaminant transport in the whole composite liner can be well described avoiding some weird phenomena in existing analytical solutions. The results of parametric study show that GCL has significant effect on improving the barrier efficiency especially for scenarios with high leachate head. The biodegradation and adsorption in GCL have significant influence on the contaminant transport through the composite liner when the half-life of contaminant in GCL is less than 5 years. Otherwise, the effect can be neglected.     

Microscale investigation into mechanical behaviors of heat-bonded nonwoven geotextile using DEM

Heat-bonded nonwoven geotextiles (HBNGs) made from synthetic fibers are widely used in engineering practices. One of the challenges on the way is to link the properties of fibers and the fabric's microstructure to the deformation and failure mechanisms of HBNGs. In this study, a random distribution geometry method was developed to reproduce the complex fibrous structure of HBNG. A piecewise linear model was adopted to reproduce the nonlinear stress-strain relationships of single fibers. The present method has been successfully applied in the simulation of uniaxial and biaxial tensile tests and puncture test. The orientation distribution of fibers and the mechanical behaviors (e.g., deformation, strain localization, force-strain relationship) of HBNG specimen were reasonably simulated. Specifically, the hourglass shape during uniaxial tensile test, the axisymmetric deformation pattern during biaxial tensile test and the trumpet shape during puncture test were all well reproduced. The present method provides an applicable tool to study the complicated mechanical behaviors of HBNG and is also helpful to obtain a better understanding of its deformation and failure mechanisms.     

食源性抗氧化肽分离纯化方法研究进展

食源性抗氧化肽是以食用蛋白质为原料经过酶解制备的具有抗氧化活性的肽。近几年来,食源性抗氧化肽因为具有分子质量小、结构简单、易于人体吸收、抗氧化活性高、在不同环境条件下稳定性强等特点,逐渐成为一种安全有效的抗氧化剂。分离纯化是获得较纯的食源性抗氧化肽的重要的一步,本文综述了几种抗氧化肽的分离纯化的方法,分别介绍了大孔树脂法,膜分离技术,色谱法,毛细管电泳法,质谱法,阐述了其在提高食源性抗氧化肽纯度方面的优缺点。未来,食源性抗氧化肽的分离纯化将是食品科学领域发展的重要研究方向。     

Catalyst failure analysis of a direct methanol fuel cell membrane electrode assembly

Lifetime testing of a single cell direct methanol fuel cell (DMFC) was carried out at 100 mA cm⁻², ambient pressure and 60 °C. X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS) were used to characterize the anode and cathode catalysts before and after lifetime testing. The XRD results showed that the particle sizes and lattice parameters of anode catalyst increased from 2.8 to 3.2 nm and from 3.8761 to 3.8871 Å; the cathode catalyst increased from 7.3 to 8.9 nm and from 3.9188 to 3.9204 Å before and after the lifetime test, respectively. The XPS results indicated that during the lifetime period, the extent of oxidation of the anode Pt and Ru components increased, and Ru appears in the XPS of the cathode. Polarization curves, power density curves, and in situ cyclic voltammetry were employed to test the performance of fuel cell and electrochemically active specific surface areas (S_EAS) of the anode and cathode catalysts before and after the lifetime test. The overall findings are that the cathode suffers the greatest degradation over the test period and that subtle changes at the anode can have substantial adverse effects on the cathode.     

强涌潮地段模袋砼的施工措施

杭嘉湖南排工程是治理太湖十项骨干工程中的关键性工程，其四个出注射器均设置于钱塘江强涌湖地段，尤以盐官下河站闸枢纽为规模最大，难度最高，通过对盐官下河站闸枢纽口门模袋砼施工的经验，提出强涌潮地段实施模袋砼工程的具体措施。具有较大的应用价值。     

一种提高红外地平仪确定卫星姿态精度的方法

红外地平仪提供了卫星星体相对于地球的姿态测量信息.受它在星体上安装精度限制、测量系统噪声和在轨期间星体质量分布变化的影响,直接使用红外测量值进行姿态计算会引入上述误差.如果只采用红外测量的差分值进行姿态计算,再通过滤波,就可以消除上述误差后得到高精度卫星姿态,这种方法充分利用了地球同步在轨卫星位置定点和姿态指向特性,对在轨运行卫星进行长时间姿态确定和实际控制结果表明该方法得到的姿态精度高于0.01°,显著提高了红外定姿精度.     

一种基带预失真RF功率放大器线性化技术的模型仿真与实验

提出了一种基于相关函数计算的自适应环延迟补偿法,用于功率放大器的的数字式基带预失真线性化技术。对采用这种软件延时补偿方法的预失真系统特性进行了仿真,并采用通用的数字信号处理器在硬件上实现了一个功放预失真系统性化模型进行了仿真,并采用通用的数字信号处理器在硬件上实现了一个功放预失真线性化模型。仿真和实验结果表明,在功率放大器的基带预失真中采用方法可以获得至少２０ｄＢ的线性度改善。     

基于移动终端日志数据的人群特征可视化

随着我国移动互联网的迅猛发展,如何从海量移动终端日志数据中提取出有效信息,并进行合理、清晰的可视化分析,为工业界等提供有价值的统计分析功能显得尤为重要.目前,对于移动终端日志数据的研究和分析多是基于对单一属性的统计结果分析,如应用下载排行、用户留存率等.为了进一步挖掘移动终端日志数据背后深层次的隐含信息,更加准确地概括出移动终端用户的特征,提出了一种基于移动应用程序日志数据的人群特征分析与画像计算方法,构造了基于移动应用程序数据的主题模型,并将移动设备用户按照与不同应用主题的相关度进行聚类,得到了具有不同特征的人群,从而提出了基于层次气泡图和Voronoi Treemap的可视化展现与分析方案.进一步将人群特征与时间信息、地理位置信息相结合,从多角度可视化展现人群特征.最后,根据该研究内容,实现了B/S架构的日志数据可视化分析原型系统,并通过案例分析验证了该方法的有效性.     

一种基于OpenFlow的SDN访问控制策略实时冲突检测与解决方法

软件定义网络SDN(Software-Defined Networking)是由美国斯坦福大学Clean Slate研究组提出的一种新型网络创新架构,可通过软件编程的形式定义和控制网络,其控制平面和转发平面分离及开放性可编程的特点,为新型互联网体系结构研究提供了新的实验途径,也极大地推动了下一代互联网的发展.OpenFlow是SDN的主要协议,定义了SDN控制器与交换机之间的通信标准.目前,很多基于OpenFlow的SDN设备已经在实际中得到了部署.但是,基于OpenFlow的SDN却面临很多安全挑战.其中一个重要的挑战是如何建立一个安全可靠的SDN防火墙应用.由于OpenFlow协议的无状态性,现有的SDN防火墙可以被通过改写交换机中的流表项轻松绕过.针对这一安全威胁,作者提出了基于Flowpath的实时动态策略冲突检测与解决方法.通过获取实时的SDN网络状态,能够准确地检测防火墙策略的直接和间接违反,并且一旦发现冲突,可以基于Flowpath进行自动化和细粒度的冲突解决.最后,作者在开源控制器Floodlight上实现了一个安全增强的防火墙应用FlowVerifier,并基于Mininet对FlowVerifier的性能进行了评估.结果表明FlowVerifier能够检测和自动化地解决SDN网络中由于流表改写而引入的策略冲突及其带来的安全威胁.