水泥混凝土泵车液压系统测试与冲击研究

根据水泥混凝土泵车实际存在的问题 ,对其在不同工况下工作时液压系统的流量、压力、温度等参数进行了测试 ,对实验数据进行了分析与处理 ,提出了减小臂架振幅 ,防止共振发生的途径和方法。     

RBF神经网络理论在发动机特性计算中的应用

运用径向基函数 (RBF)神经网络理论 ,建立发动机万有特性和外特性模型 ,并与常用的一些建模方法所建模型进行了比较。结果表明 ,应用RBF神经网络建模方法简单可靠 ,精度较高。     

高强化柴油机气缸盖水流分布试验研究

采用流动显形法对典型增压柴油机气缸盖进行水流分布试验 ,得到冷却水在缸盖中的二维流场。并对不合理的设计进行改进 ,既减小阻力又加大了流量并且提高了流速 ,使缸盖得以充分冷却。     

单指标经纬仪竖盘偏心差的精确测定及其改正

分析了单指标经纬仪竖盘偏心差对垂直角测量的影响,并推导了计算公式,以便在实际测量中加以改正,提高测量精度.     

用γ射线料位计监控胶带输送机物料堵塞

在港口胶带输送机系统中,随着输送生产率的提高和胶带运行速度的加快,转接料斗中物料堵塞的现象时常发生.输送过程中,若对堵塞现象不能及时监控并采取有效防范措施,就会导致系统的各种故障,如物料撒落、胶带破损或断裂,甚至有可能造成整个控制系统的误动作,其后果极其严重.目前,尽管很多使用单位在转接料斗处都安装有防堵塞监测装置,但还是经常发生因物料堵塞所造成的各种恶性事故.经分析认为,绝大多数是因其所设置的堵塞监测装置失效造成的.     

坯料尺寸对等径角挤压材料变形的影响

研究了坯料尺寸对等径角挤压材料等效应变及单位挤压力的影响.采用有限元法分析了不同尺寸坯料在不同摩擦条件下等径角挤压后的等效应变大小、分布与单位挤压力.结果表明,在坯料尺寸相同的情况下,随着摩擦系数的增大,坯料横截面上的等效应变略有增加,单位挤压力明显增加.在摩擦系数相同的情况下,不同尺寸坯料横截面上的等效应分布和大小基本一致,单位挤压力随坯料尺寸的增加而下降.这表明只要采用合理的润滑和模具结构,利用等径角挤压工艺可以制备出满足工业化应用要求的大块体超细晶材料.     

A two-step outlier removal procedure for surface reconstruction

Outliers in point clouds affect the performance of surface reconstruction directly. Most of outlier removal methods just remove those outliers far away from the real surface and are only applied to handle watertight surface. In this paper, a two-step outlier removal procedure is proposed to filter the point clouds acquired from the gray code and line-shifting technique. The first step is to remove the outliers far away from the real surface. Some feature points are extracted from the point clouds to construct an initial surface. The points with distances to the initial surface greater than a given threshold are removed as distant outliers. The retained points are linked into lines in each structured light sheet using their Voronoi diagrams. Some of lines which are very close to the real surface are removed as near outliers in the second step. The experimental results show that the proposed method is very effective in removing outliers for surface reconstruction. Foundation item: the National Natural Science Foundation of China (No. 30470488)     

Survey on arteriovenous fistula in maintenance hemodialysis patients with type 2 diabetic nephropathy

This paper summed up the characteristics of native arteriovenous fistulas (AVFs) in maintenance hemodialysis patients with type 2 diabetic nephropathy (DN) in Chinese hemodialysis centers. A survey was conducted on AVF in maintenance hemodialysis patients with type 2 DN. A total of 224 cases of maintenance hemodialysis patients were included in this study, among which, 65 cases in DN group, 33 cases in diabetes mellitus (DM) group and 126 cases in non-diabetic control (C) group. Hemoglobin, albumin, blood urea nitrogen, parathyroid hormone and calcium-phosphate product of the three groups of patients were not significantly different. Glycated hemoglobin A1c of DN group and DM group was not significant different. AVF life of (28.7 ± 10.0) months in DN group was significantly shorter than that of (36.5 ± 19.4) months in C group (statistic probability P <0.01), and AVF life of (32.5 ± 10.1) months in DM group (P <0.05) was also shorter than that in C group, while there was no significant difference in AVF life between DN group and DM group. Proportion of upper arm fistula in DN patients (11/65) was significantly higher than that in C group (6/123, P < 0.01). Life of AVF in patients with DN was relatively short, with more times of angioplasty and greater possibility of selecting upper arm internal fistula.     

船舶舵减横摇H∞鲁棒控制系统

研究了船舶舵减横摇鲁棒控制系统设计问题。根据船舶运动和流体力学原理,指出了舵上产生的横摇力矩及船舶航向(艏摇)与横摇的分频特性,是舵-航向/横摇综合控制技术的基础。提出广义输出干扰的概念,将舵减横摇控制系统广义对象的奇异控制问题转化为非奇异标准控制问题,给出了艏摇/横摇耦合运动的线性分式变换模型和广义对象状态空间实现,设计了舵减横摇H∞鲁棒控制系统,并用结构奇异值理论对所设计的系统进行了鲁棒稳定性和鲁棒性能分析。通过数字仿真,证明所设计的控制系统具有良好的减摇控制效果和鲁棒性。     

桥面平整度对大跨度斜拉桥车桥耦合振动的影响

将随机桥面平整度描述为零均值的平稳高斯随机过程,建立了大跨度斜拉桥空间有限元模型,考虑结构的初始应力效应和几何非线性因素,利用逐步积分法解车．桥耦合振动方程,进而对斜拉桥动力特性进行分析。