基于FLAC3D的高填方路堤通道涵洞受力特性数值分析

文章以厦蓉高速公路广西境内灌阳至全州段K13＋710通道涵洞为工程实例,利用FLAC3D（快速拉格朗日分析）软件对高填方路堤中的顶板通道进行数值仿真分析,总结了高填方路堤通道涵洞的受力特性,并提出了通道涵洞设计施工中应注意的问题。     

Virtual 3D city model as a priori information source for vehicle localization system

This paper aims at demonstrating the usefulness of integrating virtual 3D models in vehicle localization systems. Usually, vehicle localization algorithms are based on multi-sensor data fusion. Global Navigation Satellite Systems GNSS, as Global Positioning System GPS, are used to provide measurements of the geographic location. Nevertheless, GNSS solutions suffer from signal attenuation and masking, multipath phenomena and lack of visibility, especially in urban areas. That leads to degradation or even a total loss of the positioning information and then unsatisfactory performances. Dead-reckoning and inertial sensors are then often added to back up GPS in case of inaccurate or unavailable measurements or if high frequency location estimation is required. However, the dead-reckoning localization may drift in the long term due to error accumulation. To back up GPS and compensate the drift of the dead reckoning sensors based localization, two approaches integrating a virtual 3D model are proposed in registered with respect to the scene perceived by an on-board sensor. From the real/virtual scenes matching, the transformation (rotation and translation) between the real sensor and the virtual sensor (whose position and orientation are known) can be computed. These two approaches lead to determine the pose of the real sensor embedded on the vehicle. In the first approach, the considered perception sensor is a camera and in the second approach, it is a laser scanner. The first approach is based on image matching between the virtual image extracted from the 3D city model and the real image acquired by the camera. The two major parts are: 1. Detection and matching of feature points in real and virtual images (three features points are compared: Harris corner detector, SIFT and SURF). 2. Pose computation using POSIT algorithm. The second approach is based on the on–board horizontal laser scanner that provides a set of distances between it and the environment. This set of distances is matched with depth information (virtual laser scan data), provided by the virtual 3D city model. The pose estimation provided by these two approaches can be integrated in data fusion formalism. In this paper the result of the first approach is integrated in IMM UKF data fusion formalism. Experimental results obtained using real data illustrate the feasibility and the performances of the proposed approaches.     

燃油带电荷辅助雾化的激光全息摄影研究

利用发动机点火线圈次级电压作为脉冲电源,在发动机稳流气道试验台上模拟１７５单缸机的进气,用ＹＳＣ－１型运动粒子瞬态激光全息测试仪折摄了燃油油滴带电雾化和不带电雾化的粒子全息图,经再现后得到实际的粒子图,编制了专用软件进行粒子图像处理和粒径统计分布,统计结果证明燃油油滴带电后粒子粒径约减少了３／４倍左右,改善了雾化效果。     

舰艇仿真训练系统开发中三维旋转效果的二维实现

在开发舰艇仿真训练系统中,为提高操作界面的逼真程度,经常要求实现元件的三维旋转效果。文章介绍了传统的二维坐标换算和旋转三维模型方法的局限和缺点,提出了通过替换页面关系和循环引擎,在二维开发环境中实现三维旋转的效果。此方法简化了程序流程,缩短了开发周期,在舰艇模拟仿真训练系统开发过程中有着良好的表现和广泛的应用趋势。     

汽车侧碰撞儿童约束系统模型的建立及其设计参数的仿真研究

运用多刚体动力学和有限元耦合的方法建立了儿童约束系统模型,并对该模型有效性进行了验证,在此基础上运用PSM（Prescribed Structure Motion）子结构法研究侧碰撞中儿童约束系统的相关设计参数对3岁儿童乘员动力学响应及其损伤的影响,仿真结果表明,儿童安全座椅侧翼的深度、儿童座椅安全带开孔的位置、儿童座椅安全带刚度对儿童乘员的头、颈部及胸部的加速度响应影响较大,适当地调整这些参数可以降低3岁儿童乘员在侧面碰撞中的受伤风险。     

K3V型柱塞泵的结构、控制原理及维修

对广泛应用于大宇挖掘机上的K3V型轴向变量柱塞泵的结构及控制原理进行了论述,分析了常见故障的原因,给出了常见故障的排除方法及易损件的维修标准。     

桩核高度对下颌桩核基牙式全口覆盖义齿应力分布的影响

目的研究桩核高度对下颌桩核基牙式全口覆盖义齿及其支持组织应力分布的影响,为临床工作提供实验依据和指导。方法建立下颌桩核基牙式全口覆盖义齿及其支持组织的三维有限元模型,对义齿行全牙列垂直加载,分别计算当桩核根外段高度为3、4、5、6mm时义齿及其支持组织的应力值并进行比较研究。结果随着桩核根外段高度的增加,基牙牙本质、牙周膜、义齿基托及皮质骨的应力增大,黏膜的应力分布无明显改变。结论在保证义齿固位的前提下,应尽量降低桩核高度,维护组织健康。     

吸烟和β3-肾上腺素能受体基因Trp64Arg、锰超氧化物歧化酶9Ala/Val基因多态性与非酒精性脂肪性肝病的相关性

目的探讨吸烟和β3-肾上腺素能受体(β3-AR))基因Trp64Arg、锰超氧化物歧化酶9Ala/Val(MnSOD9Ala/Val)基因多态性与非酒精性脂肪性肝病(NAFLD)发病之间的关系。方法采用病例-对照研究的方法,以720例NAFLD患者及720例健康对照者的外周血白细胞为样本,采用聚合酶链反应(PCR)技术分析β3-AR基因Trp64Arg和MnSOD9Ala/Val基因多态性。结果β3-AR基因Trp64Arg(A/A)基因型和MnSOD9Ala/Val(V/V)基因型频率分布分别为39.4%、71.7%(病例组)和21.1%、43.3%(对照组),差异有统计学意义(P<0.01;P<0.01)。Trp64Arg(A/A)基因型者患NAFLD的风险显著增加(OR=2.434,95%CI=1.816~4.075)。MnSOD9Ala/Val(V/V)基因型者患NAFLD的风险也显著增加(OR=3.308,95%CI=1.913~4.509)。基因突变的协同分析发现,Trp64Arg(A/A)/MnSOD9Ala/Val(V/V)基因型者在NAFLD组和对照组中的分布频率分别为32.8%和6.5%,差异有统计学意义(P<0.01)。Trp64Arg(A/A)/MnSOD9Ala/Val(V/V)基因型者患NAFLD的风险显著增加(OR=9.753,95%CI=4.292~12.426)。病例组的吸烟率显著高于对照组(OR=2.623,95%CI=1.425~4.957),Trp64Arg(A/A)/MnSOD9Ala/Val(V/V)基因型与吸烟有协同作用(OR=33.764,95%CI=18.907~61.582)。结论 Trp64Arg(A/A)/MnSOD9Ala/Val(V/V)基因型和吸烟是NAFLD的易患因素,三者的联合在NAFLD的发生中起着协同的作用。     

三点弯曲梁裂缝应力强度因子有限元分析

利用有限元数值模拟方法对一定尺寸的砼三点弯曲梁三维裂缝进行分析,得出应力强度因子KI随裂缝长度和荷载水平变化时的变化规律,并通过与已有经验公式的比较,验证有限元裂缝分析方法的正确性.并归纳出KI简化计算公式.     

1,25-(OH)2D3及复方丹参对大鼠异基因骨髓移植后造血重建及T细胞亚群的影响

目的 观察1,25-(OH)2D3及丹参对异基因骨髓移植(Allo-BMT)后造血重建和T细胞亚群的影响.方法 受鼠随机分成4组:A组(急性移植物抗宿主病,即aGVHD组),B组(1,25-(OH)2D3组),C组(丹参组),D组(两药联合组).观察大鼠生存期、外周血象、aGVHD的临床表现及T细胞亚群.结果各药物干预组与aGVHD组相比,其aGVHD的发病时间延迟、aGVHD评分降低、平均生存时间明显延长,差异均有统计学意义(P<0.05);各药物干预组外周血象恢复较快,在各不同时间点的变化均高于aGVHD组,差异亦有统计学意义(P<0.05);经干预方案处理后,CD4+、CD8+的数值明显较aGVHD降低,以CD4+细胞下降明显,而aGVHD时二者均明显增加,CD4+/CD8+的比值增大,结论 1,25-(OH)2D3及复方丹参在异基因骨髓移植后对减轻aGVHD、促进造血重建及发挥免疫耐受有积极的作用.