The intersection marker method for 3D interface tracking of deformable surfaces in finite volumes

Currently, the majority of computational fluid dynamics (CFD) codes use the finite volume method to spatially discretise the computational domain, sometimes as an array of cubic control volumes. The Finite volume method works well with single‐phase flow simulations, but two‐phase flow simulations are more challenging because of the need to track the surface interface traversing and deforming within the 3D grid. Surface area and volume fraction details of each interface cell must be accurately accounted for, in order to calculate for the momentum exchange and rates of heat and mass transfer across the interface. To attain a higher accuracy in two‐phase flow CFD calculations, the intersection marker (ISM) method is developed. The ISM method is a hybrid Lagrangian–Eulerian front‐tracking algorithm that can model an arbitrary 3D surface within an array of cubic control volumes. The ISM method has a cell‐by‐cell remeshing capability that is volume conservative and is suitable for the tracking of complex interface deformation in transient two‐phase CFD simulations. Copyright © 2015 John Wiley & Sons, Ltd.     

“数字城管”外业普查与建库的质量控制

以某市"数字城管"外业普查与建库项目为背景,重点探讨了项目实施过程中各个阶段的质量控制要点。     

高校 ERP 综合实验课程的调查与思考

基于高校ERP综合实验课程的详细调查分析，在深入剖析影响ERP综合实验教学效果原因的基础之上，从专业课程整合、教学方式、方法和教学管理改革等方面提出了一些思考建议。     

考虑运动受限的履带式移动机器人轨迹跟踪控制

针对履带式移动机器人的轨迹跟踪控制问题进行研究,首先,建立了履带式移动机器人的运动学模型和跟踪误差模型；其次,设计了转速有限时间控制和线速度滑模控制的轨迹跟踪控制律,并给出了考虑运动受限作用下的控制律修正表达式；最后,基于MATLAB对所提控制律进行仿真,对比分析了不考虑运动受限情况下跟踪控制效果;结果表明,设计的跟踪控制律能够实现履带式移动机器人对圆轨迹的有效跟踪,且考虑运动受限作用的控制律更加符合实际;文章研究分析了运动受限作用对于移动机器人轨迹跟踪控制的影响,分析结果对其他移动机器人的运动控制研究具有参考价值。     

环路跟踪卡尔曼滤波算法的性能分析

基于卡尔曼滤波的环路跟踪算法多是通过一定仿真证明算法性能,没有系统性性能评估,难以较好指导工程应用。在原有算法基础上进行了优化,并系统性地对比分析、评估了基于卡尔曼环路滤波算法性能,以期为算法工程化提供指导。首先提出对跟踪环路反馈调整量进行预测,使之更符合系统实际,减小环路跟踪误差。而后基于卫星信号模拟器输出信号和自生产信号源,充分评估基于卡尔曼滤波环路跟踪算法的收敛时间和灵敏度。仿真结果表明,相比目前工程常用的二阶FFL辅助三阶PLL算法,基于卡尔曼滤波环路跟踪算法能够缩短环路所需稳定时间约90%,并能提升跟踪灵敏度约5 d B,有效改善弱信号场景中接收机输出信息的完好性和连续性。     

实时三维超声心动图与二维斑点追踪成像技术共同评价心肌梗死患者左室收缩功能与同步性

目的探讨二维斑点追踪成像(2D-STI)及实时三维超声心动图(RT-3DE)评价AMI患者左心室收缩功能和各节段运动的同步性.方法 50例急性心肌梗死患者为病例组,30例正常体检者为对照组,应用CMQ软件获取各节段径向圆周应变及应变率曲线,然后转变为RT-3DE模式,得到17节段时间-体积曲线(VTC),并获得收缩功能以及非同步收缩参数.结果 1)与对照组相比,心肌梗死组3个水平所有节段径向应变值和圆周应变值均减低;2)心梗组患者Trs-SD,Tcs-SD,Trsr-SD,Tcsr-SD明显高于对照组(P0.05);3)与单支冠状动脉病变心梗组比较,多支冠状动脉病变心梗组LVEDV,LVESV显著增加,LVEF显著减小;4)病例组患者左室Tmsv17-SD,Tmsv17-Dif,Tmsv17-SD%,Tmsv17-Dif%均较对照组增大(P0.05).结论 RT-3DE和2D-STI可以准确地量化左室收缩功能,评价AMI患者左室运动的同步性,左室收缩功能障碍也影响收缩同步性.     

The influence of home environmental factors and life style on children＇s respiratory health in Xi＇an

To assess associations between home indoor air environments and asthma,allergies and pneumonia,children aged 1–8 years were surveyed from 12 kindergartens in the city of Xi’an.2,020 questionnaires were responded with a response rate of 83.5%.The prevalences of doctor diagnosed asthma,hay fever,and pneumonia were 2.9%,3.6%,and 28.3%,respectively.Living close to a highway was a risk factor for current rhinitis(AOR 1.5,95%CI 1.2–1.8),eczema(AOR 1.7,95%CI 1.2–2.5),and diagnosed pneumonia(AOR 1.3,95%CI 1.0–1.6).Dampness problems in the home were associated with 50%–130%increases in the prevalences of asthma and allergy.Airing bed linen under sun-shine was protective,especially against rhinitis.Pet avoidance was consistently and significantly associated with asthma and allergy(AOR 1.3–2.4).Decoration of the home during children’s early life is a risk factor for current rhinitis(AOR 1.9,95%CI 1.3–2.9)and eczema(AOR 1.9,95%CI1.1–3.6).Risk factors for pneumonia were living in an apartment(AOR 1.4,95%CI 1.1–1.8),latex wall paint(AOR 1.3,95%CI 1.0–1.7),dampness(AOR 1.4–1.5),breast feeding\3 months(AOR 1.3,95%CI 1.0–1.7),never airing bed linen in sunshine(AOR 1.3,95%CI1.3–1.6),and cleaning children’s room less frequently than once per day(AOR 1.4,95%CI 1.1–1.7).This study demonstrates that home indoor environmental and life style factors may influence the health of children in Xi’an.     

浅析GPS在工程控制测量中的应用

目前,GPS系统已广泛应用于大地测量、工程测量、航空摄影测量以及地形测量等方面。以大同市两区改造项目为例,概述了GPS系统在工程控制测量中的应用。     

A velocity program using the Kanade–Lucas–Tomasi feature-tracking algorithm with demonstration for pressure and electroosmosis conditions

Investigating microfluidic flow profiles is of interest in the microfluidics field for the determination of various characteristics of a lab-on-a-chip system. Microparticle tracking velocimetry uses computational methods upon recording video footage of microfluidic flow to ultimately visualize motion within a microfluidic system across all frames of a video. Current methods are computationally expensive or require extensive instrumentation. A computational method suited to microparticle tracking applications is the robust Kanade–Lucas–Tomasi (KLT) feature-tracking algorithm. This work explores a microparticle tracking velocimetry program using the KLT feature-tracking algorithm. The developed program is demonstrated using pressure-driven and EOF and compared with the respective mathematical fluid flow models. An electrostatics analysis of EOF conditions is performed in the development of the mathematical using a Poisson's Equation solver. This analysis is used to quantify the zeta potential of the electroosmotic system. Overall, the KLT feature-tracking algorithm presented in this work proved to be highly reliable and computationally efficient for investigations of pressure-driven and EOF in a microfluidic system.     

基于CSI离散指纹的轨迹跟踪方法

针对从Wi-Fi设备中获取的接收信号强度(RSSI)在定位过程中误差较大的问题，设计了一种基于信道状 态信息(CSI) 离散指纹的轨迹跟踪方法．首先经过汉佩尔滤波，巴特沃斯低通滤波去除了CSI异常值和噪声的影响， 然后利用线性回归算法去除相位的频移误差，继而采用协方差矩阵特征值法进行特征提取，最后通过基于CSI子 载波权重的主成分分析法进行了无源定位和轨迹跟踪．实验结果表明: 离散指纹点定位的平均正确率在 90%以上， 所设计的算法能有效实现对室内人员的定位和轨迹跟踪．