实时数字PCR扩增曲线的分类

传统的数字PCR检测仅针对扩增终点的核酸样本执行终点式的荧光分析,依据反应后的荧光图像进行阴阳性统计及样本浓度计算,分析结果极易受假阳性及非特异性扩增影响。本文提出了一种基于过程的实时微孔式数字PCR芯片阴阳性分析方法,从时间维度对数字PCR结果进行定量分析,提高数字PCR检测的准确性。设计支持实时数字PCR分析的硬件系统并与终点式数字PCR仪进行对比,验证系统性能。在此系统上检测不同浓度的人类Ⅳ型疱疹病毒样本,获取实时扩增曲线,采用支持向量机算法对扩增曲线的特征进行学习并应用于检测曲线分类。实验结果表明,所设计的实时数字PCR系统与终点式数字PCR仪扩增结果具有高度一致性。本文所述的基于支持向量机的分类算法对扩增曲线的分类准确率达到98%以上,能准确识别假阳性及非特异性扩增微孔。相比于传统阈值分割法,本方法对阳性点识别的平均准确率提高了17.60%,并且目标模板拷贝数越低,效果越明显。与传统的终点式数字PCR相比,本文提出的基于实时数字PCR系统的数据分析方法具有准确性更高的优势,尤其在低拷贝数检测下可以获取更为精确的定量结果。     

微滴制备及其均一性检测

文中基于电磁力振动原理,采用蒸馏水作为微滴喷射材料,搭建了微滴发生器,利用高速摄影机采集微滴下落过程图像,并基于MATLAB图像处理技术研发了用于计算微滴几何参数的微滴检测系统。实验结果表明:在喷嘴孔径和气压分别为0.33 mm和0.7 kPa条件下,扰动频率分别为600、800、900 Hz时,可获得均一微滴;公式法计算得到的平均直径和微滴检测系统计算的平均直径之间的最大误差为2.5%,通过误差传递公式计算出球形度的最大误差为5.89%,说明基于MATLAB设计的微滴检测系统具有较高的可靠性。     

气压驱动金属微熔滴可控喷射及沉积精度分析?

金属微滴按需喷射成形制造中,保证喷射系统按需产生均匀微滴和喷射沉积的位置精度是成形高质量金属零件的关键。采用试验研究的方法,分析喷嘴壁附着杂质对稳定喷射以及工艺参数对微滴均匀性的影响,并对喷射系统在可控喷射情况下按需产生的锡铅合金(Sn60%Pb40%)微滴尺寸分布进行分析;研究沉积高度变化对微滴沉积精度的影响。在上述研究基础上,通过选择合适的沉积高度,沉积制造一个6×6微滴阵列,并对微滴阵列的沉积精度进行分析。结果表明,所产生微滴的平均直径为321μm,尺寸标准偏差为2.897μm,约99%的颗粒分布在平均直径±2.8%附近区间内,分布较集中,均匀性较好;得到了发散距离随沉积高度增加而增大的变化趋势;成形的微滴阵列精度满足制造要求。为后续成形高质量微小金属零件提供必要的基础。     

使用ABC分类法分析和管理气象装备库存器材

根据帕累托ABC分类法的基本原则,就气象装备器材的库存分类方法和库存管理策略等进行分析和探讨。ABC分类法考虑了库存管理中主次因素,对库存器材分类的结果更加符合实际。使用Excel软件制作气象装备器材库存ABC分类表,可以大大提高工作效率。本文还提出了ABC分类法管理策略与特殊性管理相结合的改进意见。     

微滴喷射中喷嘴间距对微滴轨迹影响的研究

以某款压电阵列式喷头为研究对象,喷射液体材料选用呋喃树脂,研究微滴喷射中喷嘴间距对微滴喷射轨迹的影响规律。采用守恒水平集方法建立了微滴喷射多喷嘴的仿真模型,通过实验和仿真相结合的方法分析了实验驱动电压和仿真入口压强的关系,通过拟合公式法得出二者拟合关系式。数值模拟结果表明,在该阵列式喷头的喷射过程中,相邻液滴有相互靠近的趋势。喷嘴间距和液滴实际喷射轨迹与理想喷射轨迹之间偏移的距离阈值存在一定的线性关系。当喷嘴间距小于距离阈值时,液滴实际喷射轨迹几乎不受影响;而当喷嘴间距大于距离阈值时,液滴实际喷射轨迹会偏离理想喷射轨迹。     

连续灰度微滴喷射控制系统的研制

针对灰度微滴喷射技术中传输数据量大和传输数据不匹配的问题,对灰度微滴喷射的技术特点进行了分析,对灰度微滴喷射技术的控制方法进行了归纳,提出了一种基于ARM+FPGA系统架构和双口RAM乒乓操作技术的灰度微滴喷射控制系统,采用Modelsim软件对FPGA内部模块进行了时序仿真,利用搭建的灰度微滴喷射实验平台对灰度色阶和边缘锯齿进行了测试。实验结果表明,该系统能够实现最大幅面为280 mm且具有8个灰度等级的微滴喷射,打印的图像边缘锐利清晰无明显锯齿。     

压电式喷头的微滴喷射行为及其影响因素

设计并加工了一种压电式微滴喷头,并在微滴喷射平台上进行了微滴喷射实验,用CCD相机拍摄到了液滴形成的整个过程。通过激光位移测量平台测量了压电片的振荡曲线,并将位移曲线输入流体模拟求解器,用两相的方法模拟出了微滴形成的过程。模拟显示液滴的形成时间,大小,形状和速度与实验结果拟合得很好。通过对比液滴的形成过程与压电片的振荡曲线,发现主液滴在压电信号为高电平时,已经脱落了微滴喷嘴,基于此提出了通过改变高电平时间和增加压电片的自由振荡衰减阻值提高微滴喷射最高频率的方案。通过微滴喷射行为模拟,解释了微滴喷射实验中出现两条液滴的原因,并通过改变喷腔结构和改变液体黏度,找到了减少额外液滴出现的途径。     

收缩管型压电式喷头微滴喷射仿真及实验研究

为探究收缩管型压电式喷头微滴喷射过程中内部流场变化规律以及微滴形成过程,利用Gambit软件建立二维轴对称有限元模型,基于Fluent动网格技术,采用VOF两相流模型,对微滴喷射过程进行仿真分析,研究了微滴形成机理。建立微滴喷射系统对微滴喷射过程进行实验,分析收缩管型压电式喷头工作时入口压强对尾滴、附着液滴形成的影响规律。结果表明:储液腔的振动边界运动引起内部压强变化,导致长液带形成,并断裂形成微滴;入口压强影响尾滴与附着液滴的形成;特定振动边界运动存在对应的可用入口压强范围。     

超阈值模型中时域外推GPD估计方法选择

在进行载荷谱时域外推时,为更好地估计超阈值载荷数据所服从的广义帕累托分布(Generalized Pareto Distribution,GPD)参数,分别对比极大似然估计(Maximum Likelihood Estimation Moments,ML)、矩估计(Method of Moments,MoM)及概率加权估计(Probability Weighted Moments,PWM)对GPD分布参数选取的影响,并选取最优参数估计方法。首先搭建了挖掘机压力测试系统,并采集挖掘机在典型工况工作下载荷数据;其次以最小均方根误差所对应值为最优阈值,分别计算3种参数估计方法所对应最优阈值及GPD拟合参数;最后分别绘制3种参数估计方法下超阈值载荷数据和GPD拟合CDF图和Q-Q图。结果表明:3种参数估计方法的拟合结果和超阈值样本之间的相关系数均在0.99以上,都可以较好地拟合超阈值载荷数据的GPD分布,但PWM参数估计方法能够包含较多有效载荷数据且拟合效果更好。     

基板倾斜角度对3D打印微滴成形形貌的影响研究

为研究微滴喷射3D打印过程中基板倾斜角度对微滴成形形貌的影响,以低熔点铅锡合金为研究对象,通过实验和仿真研究微滴分别与0°、15°、30°、45°、60°倾角的基板碰撞动力学特性及微滴形貌成形规律。结果表明,基板倾角对微滴铺展的对称性和形貌有着主要影响,随着倾角的增大,微滴铺展的不对称性也随之增大。在一定倾斜角范围内,微滴与基板碰撞后铺展程度变化不大,微滴沿壁面滑移距离变化较为平均,随着倾斜角增大到一定程度,铺展程度变化显著,滑移距离变化较大;微滴的惯性力对微滴碰撞前期的变形影响较大,微滴成形后期其形貌主要受张力、应力和粘性力的影响。     

采样样本的容量对雾滴尺寸测量精度影响的试验研究

用雾滴采集装置在自行建立的高压喷雾系统上对雾滴进行了样本采集,用机器视觉方法对雾滴尺寸进行了统计与测量,将机器视觉方法测量结果与PDPA测量结果相比较,深入分析了雾滴采样样本对雾滴尺寸测量精度的影响.试验结果表明:雾滴采样样本容量越大,雾滴尺寸测量精度也越高,当雾滴样本容量大于4 000个时,雾滴特征直径D0.632的测量精度可达5%以内;不同粒径的雾滴个体对雾滴尺寸测量精度的影响不同,大粒径雾滴对尺寸测量精度的影响远大于小粒径雾滴,雾滴尺寸测量时尤其应注意准确统计大粒径雾滴.     

圆管式压电喷头的液体分配

针对用于喷墨打印的圆管式压电喷头建立了计算模型,并且根据它的驱动特点选择了合适的边界条件。介绍了仿真软件针对自由表面流动问题的计算原理。然后,以乙二醇水溶液为例,计算了压电喷头分配该溶液的分配过程;利用液滴成像系统获取了不同时刻的液滴图像,验证了建立的模型和数值算法的正确性。最后,计算了压电喷头在不同输入位移、不同黏度以及不同表面张力下的液体分配过程。仿真结果显示:液体分配性能与激励位移密切相关,在72.5mN/m的表面张力作用下,10nm的输入位移很难分配黏度为4.0mPa·s的液体,而15nm的输入位移在分配黏度为4.0mPa·s液体时却能够产生卫星液滴。因此,对于某种液体寻找一个合适的激励条件非常重要,过小的激励产生不了液滴,过大的激励则会产生较大甚至多个卫星液滴;增大黏度会延缓或阻滞液滴形成过程,增大表面张力却能加快液滴形成过程。本文的计算方法对于研制新式喷头或者研究喷头的喷射能力均具有指导意义。     

Multi – oil droplet recognition of oil-water two-phase flow based on integrated features

Multi-oil droplet target recognition is one of the applications of machine vision in the measurement of oil-water two-phase flow parameters, which could combine other algorithms to obtain the oil droplet velocity and the water holdup of oil water two-phase flow. Appropriate target representation features can improve the recognition effect of multiple oil droplets. However, due to shooting environment differences and quality differences of oil-water two-phase flow images, existing target representation features do not perform well in low-quality oil-water two-phase flow images. To improve the precision of multi-oil droplet target recognition in oil-water two-phase flow and reduce the miss rate, this paper constructs an integrated feature on the basis of aggregate channel features (ACF). The integrated feature named aggregate channel features with histogram of local gravitational feature（ACFHG） contains the color feature channels reflecting the overall color features of the oil droplet sample, the gradient amplitude channel reflecting the overall gradient of the oil droplet sample image, the gradient direction histogram feature channels reflecting the local gradient of the oil droplet sample image, and the local gravitational feature channels that ensure oil droplet target recognition in low quality photos and photos taken in complex shooting environments. Moreover, the rotation invariance is obtained by taking the oriented gradient histogram of the local gravitational feature to further improve the multi-oil droplet target recognition effect. Experiment results show that the average precision of multi-oil droplet target recognition using the integrated features is 83.38%, which is 9.93% higher than that with using ACF, and the miss rate is 9.13%, which is 57.18% lower than that with using ACF. Compared with other existing target detection methods, the method proposed in this paper still has an advantage in the rate of missed detection.     

Predication and measurement of deflected trajectory and temperature history of uniform metal droplets in microstructures fabrication

The deposition of metal droplets has been attracted wide interests for potential applying in microstructures fabrication. A uniform droplet generator with image acquiring system and droplet temperature measuring system was established. A coupling analysis method on combination of droplets dynamic and thermal models was proposed. Effect of experimental parameters on deflected trajectory and the temperature history of the uniform droplets was investigated. The measured trajectory and temperature history agreed well with the predicted results, indicating the validity of the proposed analysis method. The predicted results with different experimental parameters showed that the deflected trajectories and thermal histories of the droplets with diameters close to 100???m or less were strongly dependent on their sizes. Small droplets had a narrow deposition length for obtaining parts with good metallurgical bonding. The predicted results also showed that it was effective in controlling the deflected trajectories and thermal histories of droplets by adjusting the pressure when it was low. At last, micro alloy tubes with good metallurgical bonding were obtained using 50???m diameter nozzle when the experimental parameters were chosen according to theoretical models. The deposited results show that proper parameters for microstructures deposition can be obtained according to the proposed analysis method.     

Adaptive calibration of a capacitance tomography system for imaging water droplet distribution

A highly sensitive electrical capacitance tomography (ECT) system based on an HP4284 impedance analyser has been developed and used to quantify low concentration multi-phase flows in wet gas separation processes. The system hardware provides high accuracy (0.05%) and high resolution (10⁻¹⁷ F). The sensor was calibrated in an environmental chamber with solid samples of known permittivity over ranges of temperature and humidity. Adaptive calibration and adjacent electrode pair correction techniques were applied to image very low concentration profiles. This paper describes the techniques used and presents the experimental results obtained from a test flow rig called Twister, which has been designed to separate liquid droplets from wet gas streams. The test results over a range of operating conditions (20–95% humidity) demonstrate that the ECT system is capable of reconstructing clear images of the droplet distribution inside Twister. Changes as small as 1 gWater/kgAir in the form of liquid droplets were detectable. It has also been shown that the concentration of the condensable phase can be estimated quantitatively within 20% in comparison with the reference measurements.     

Group vaporization of liquid fuel sprays

In the simplest models of spray combustion it is assumed that the droplets burn individually according to the “d²-law.” Both theory and experiment show that this model only will be valid if the spray is extremely dilute, otherwise the droplets burn collectively in what is known as the group combustion mode. Most of work on spherical droplet cloud is limited to monodisperse sprays; however it is important to determine how the particle size distribution will affect group combustion, particularly the sheath combustion mode. In order to gain preliminary indication of the effect of the droplet size distribution of the vaporization process, the behavior of spays with a bimodal droplet size distribution is examined. The present study shows that for a cloud which is initially in saturated equilibrium the droplet size distribution changes the profiles of temperature and fuel vapor mass fraction within the vaporization wave at the edge of the cloud; however, the size distribution does not affect the overall evaporation characteristics such as the vaporization rate and the cloud lifetime in the sheath combustion limit considered here. It is shown that as before the cloud radius decreases according to a “d²-law” with a modified vaporization constant.     

薄膜Lamb波传感器用于胃蛋白酶原I检测

为满足大规模胃癌早期筛查对胃蛋白酶原I(PGI)检测高灵敏度、高效率、操作简单、样品量少的需求,本文构建了一种PGI抗体功能化薄膜型Lamb波生物传感器。对传感器检测腔薄膜进行PGI抗体自组装修饰,传感器检测腔表面修饰的PGI抗体将样品中PGI抗原特异性的捕获并固定在检测腔薄膜表面,Lamb波传感器薄膜表面质量增加导致其A0模式中心频率发生移动,且频率移动量与检测腔表面吸附物质质量增加量正相关,实现对样本中PGI抗原浓度的检测。实验结果表明:PGI抗体功能化薄膜Lamb波生物传感器对PGI抗原实测灵敏度约为102.114 Hz/ng/mL,理论最低检测限(LOD)为0.176ng/mL,单个样本检测时间为40min,与现有基于光学检测法PGI检测技术相比,具有检测系统简单、操作简单、不需要专业人员操作等显著优势,且比多数光学检测法LOD更低,比电化学法PGI检测技术LOD低两个数量级。结果表明,本文提出的PGI抗体免疫功能化薄膜型Lamb波生物传感器对PGI检测且具有检测下限低、灵敏度高、检测效率高、操作简单、无需样品预处理等特点,满足大规模早期胃癌筛查的基本需求。     

瞬态激振影响下微油滴撞壁行为的数值模拟研究

在油气微量润滑系统工作过程中,有效润滑是保障零件稳定运行的关键。但工作零件的振动会影响油滴的铺展,扰动润滑油膜的形成,从而影响零件的润滑效果。基于CLSVOF方法,建立油滴撞击振动壁面的模型,考察油滴撞击瞬时激振壁面过程中的油液形态演化规律。研究发现：油滴撞击激振壁面后产生飞溅和颈部射流现象;在不同振动频率下,油滴冲击产生二次飞溅的时间均整个周期的1/5附近;壁面振动减小了油滴的最大铺展因子,延长了油滴的铺展时间;在回缩阶段,油滴铺展因子呈现出典型的振荡衰减态势。     

Atomization of fuel mixtures

The combustion process of a coal/oil slurry begins by atomization of the slurry. This project is a presentation of experimental system and results on atomization of coal/oil(COM) and coal/methanol mixtures with a twin-fluid and a wheel atomizer. The slurries are consisted of coal/methanol and coal/oil mixtures with two different concentrations and two coal particile sizes. The volume median diameters of the coal particles were 45 and 130 microns. The oil was No. 2 diesel oil. The droplet size was determined by photographing the spray and the photographs were analyzed to determine droplet size and distribution. The results show that the inclusion of particles in the liquid(both methanol and diesel oil) does not appreciably affect the atomized droplet size. The tendency is for the slurry droplets to be somewhat smaller than the droplets atomized with the pure liquid.     

The application of X-ray analysis in the transmission electron analytical microscope (T.E.A.M.) to the quantitative bulk analysis of biological microsamples

This paper describes: (a) methods for the high and low temperature ashing of biological tissue samples about 10^?4–10^?5 g in weight; (b) a method of spraying the solubilized ash on to specimen grids which produces droplets of a size convenient for their quantitative analysis in a transmission electron analytical microscope (T.E.A.M.), but without the need to know the actual volume of individual droplets; (c) the construction of standard curves for determining the absolute concentration of Na, Mg, P, S, K, and Ca simultaneously in a given sample. For most of the elements the error in analysis was about 5% or less. It was proposed that the technique is useful for detecting local element-compartments in complex tissues, and thus may be an important aid in the interpretation of the results of point analyses performed on sections taken from adjacent micro-volumes.