扩散管胀口模具设计

扩散管是用于长安牌微型汽车消声器中的薄壁管件，见图 1，材料为 29× 1.5的镀锌无缝钢管。在一般对于大批量薄壁管件的成型加工中，多采用专用管端成形机床，它具有生产效率高、加工出的工件尺寸精确、产品质量好等优点，但设备投资较大；如在普通压力机上，采用专用模具来完成薄壁管件的成形，则为一种较好的工艺方法。 [1] 模具结构与工作原理 　　扩散管胀 (扩 )口模具结构如图 2所示。其工作原理为：当模具安装块 14在上极限 (死点 )位置时，胀 (扩 )口模处于待工作状态，将待加工的扩散管套在胀 (扩 )套 2上，依靠限位套 4定位，确…     

气源净化技术问答

答:扩散沉积是由布朗运动引起的。粒径在1μm以下的气溶胶粒子(如油烟、烟雾等)在很慢的气流中会产生一种不规则的直线运动,这种运动在物理上称为布朗扩散。作布朗扩散的粒子,由于其直线运动距离很短,在较快的气流速度及较大的纤维间隙中不起明显的作用。但在较慢的气流速度和较小的纤维间隙中,对于粒径小于0.1μm气溶胶粒子,布朗扩散的作用就变得非常明显,其结果是大大增加了微粒与纤维的接触机会。布朗扩散机理对纤维过滤器捕集粒径小于0.5μm微粒起着重要作用。     

CrMo钢板的金属尘化腐蚀扩散模型研究

基于Fick第二定律、化学动力学及扩散热力学,推导得到了扩散、化学反应等因素耦合作用下的修正Fick 2定律,以薄板为对象,差分求解得到尘化腐蚀过程中不同因素作用下基于两种扩散模型内部瞬时碳浓度分布图,并结合Cr5Mo钢的尘化腐蚀试验,分析了化学反应因素在扩散中作用。研究结果表明：c-Fick 2中修正项系数k～值对计算得到的浓度值有重要的影响;随着k～值的增大,浓度值下降得越多,当k～≤1时对扩散的影响不显著;本试验条件下k～=2.0769,化学反应因素对碳扩散的影响较小,该模型可以描述尘化腐蚀试验过程中的碳浓度分布情况,对尘化腐蚀程度的预测提供了依据。     

扩散管涨口模具

扩散管是长安牌微型汽车消声器的薄壁管件（图1），材料为29mm×1．5mm的镀锌碳素无缝钢管。采用专用管端成形机床加工，设备投资较大。为此我们在普通压力机上，采用专用模具，完成了薄壁管件的成形加工。1模具结构与工作原理扩散管涨口模具如图2所示。其工作原理是：当模具安装块14在上极限（死点）位置时，涨口模具处于待工作状态，将扩散管毛坯套在图2扩散管涨口模具涨套2上，依靠限位套4定位，确定零件涨口长度尺寸，随后安装块14与上滑座12一起由压力机控制向下运动，推动滑块8沿滑动导轨带动芯轴1向右移动，弹垫11在容框10内压缩，涨…     

光子计数探测器感应位敏阳极的电子云扩散

针对基于感应位敏阳极的光子计数成像探测器中非晶态Ge(α-Ge)膜的方块电阻对探测器成像性能的影响,研究了方块电阻的选配范围和方法。由于方块电阻的大小会影响Ge膜上的电子云的扩散特性从而影响探测器的计数率和分辨率,故本文根据菲克(Fick)扩散定律分析了吸收边界条件下非晶态薄膜上电子云的扩散特性。确定了电子云扩散时间与Ge膜方块电阻之间的数学关系,推导获得了探测器高质量成像时非晶态Ge膜方块电阻的阻值为30～2 700MΩ/□。采用具有不同方块电阻的感应位敏阳极进行了实际成像实验,结果表明:当Ge膜方块电阻在上述范围时,光子计数探测器在计数率为53kc/s时分辨率可以达到0.5mm。实验结果证明了推导得出的方块电阻选配范围的正确性。     

先进制造模式的多阶段扩散模型研究

为了揭示先进制造模式的扩散规律,为企业决策及政府调控提供理论依据,从先进制造模式扩散的阶段性视角对其扩散行为进行研究.首先讨论先进制造模式扩散过程中的影响因素,分析扩散的特点和扩散机制,然后对企业的应用能力进行区分,并且考虑外部影响,建立先进制造模式的多阶段扩散模型;随后对该模型的稳定性及灵敏度进行分析;最后以计算机集成制造系统(CIMS)的扩散为例,建立多阶段扩散模型,并应用Vensim软件对模型进行仿真及分析,验证模型的正确性,同时给出模型的应用策略.     

扩散焊温度对GH4169内部流道的影响规律研究

采用真空扩散焊技术对GH4169高温合金进行焊接,研究扩散焊温度对于扩散焊连接强度和内部流道变形的影响规律。结果表明：GH4169在16 MPa下直接扩散连接,扩散焊温度区间为1100～1150℃,扩散焊接头强度可达母材的85%以上;流道进口处的收缩量明显大于内部流道,且沿扩散焊方向,流道收缩量由内部向两侧逐渐变大。     

采用膜分离技术回收合成氨驰放气

以中空纤维膜两侧气体的分压差为推动力，通过渗透-溶解-扩散-解析等步骤，利用中空纤维膜对各种气体的选择透过性不同，分离回收合成氨驰放气中的氢气，经压缩后重返氨合成系统，提高了合成氨产量，效益可观。     

热处理对铝合金化学镀镍-钨-磷镀层组织性能的影响

通过扫描电子显微镜、能谱微区成分分析、透射电镜等手段研究了热处理对6061铝合金化学镀镍-钨-磷合金镀层组织性能的影响.结果表明:在试验热处理条件下,镍-钨-磷镀层和基体问扩散主要是镍原子向铝基体中的扩散;铝合金化学镀镍-钨-磷试样525℃热处理1 h后,由于镍原子的扩散,基体和镀层之间形成镍铝合金层,镍铝合金层分为二层,第一层镍铝合金层主要含有Ni2Al3相,第二层镍铝合金层主要含有NiAl3相;在干摩擦滑动条件下,铝合金化学镀试样经525℃热处理1h后表现出良好的耐磨性.     

表面无序亚微米结构高效扩散膜

提出了表面无序亚微米结构高雾度和高透光率扩散膜的制备方法。通过模板复制法,基于硅锥模板和阳极氧化铝模板制备了具有表面无序亚微米结构的聚二甲基硅氧烷(PDMS)和聚苯乙烯(PS)薄膜。结果表明,表面无序亚微米结构可以显著增加薄膜的雾度。结构的形貌和尺寸对薄膜光扩散性能有重要影响,其中利用锥径650nm的硅锥模板得到的具有表面无序亚微米孔结构的PDMS薄膜的雾度达到92%,透光率为90.9%,有效散射系数为83.7%;同一模板制备的PS薄膜的雾度达到97.9%,透光率为85%,有效散射系数为83.2%;这二种微结构薄膜都可用作高效扩散膜。结果表明:利用硅锥模板制备这种高效扩散膜,工艺简单、成本低,对聚合物材料没有选择性,有望实现高性能扩散膜的大规模生产。     

Fluorescence recovery after photobleaching and photoconversion in multiple arbitrary regions of interest using a programmable array microscope

Photomanipulation (photobleaching, photoactivation, or photoconversion) is an essential tool in fluorescence microscopy. Fluorescence recovery after photobleaching (FRAP) is commonly used for the determination of lateral diffusion constants of membrane proteins, and can be conveniently implemented in confocal laser scanning microscopy (CLSM). Such determinations provide important information on molecular dynamics in live cells. However, the CLSM platform is inherently limited for FRAP because of its inflexible raster (spot) scanning format. We have implemented FRAP and photoactivation protocols using structured illumination and detection in a programmable array microscope (PAM). The patterns are arbitrary in number and shape, dynamic and adjustable to and by the sample characteristics. We have used multispot PAM–FRAP to measure the lateral diffusion of the erbB3 (HER3) receptor tyrosine kinase labeled by fusion with mCitrine on untreated cells and after treatment with reagents that perturb the cytoskeleton or plasma membrane or activate coexpressed erbB1 (HER1, the EGF receptor EGFR). We also show the versatility of the PAM for photoactivation in arbitrary regions of interest, in cells expressing erbB3 fused with the photoconvertible fluorescent protein dronpa. dronpa. Microsc. Res. Tech., 2009. © 2009 Wiley-Liss, Inc.     

Polarized fluorescence correlation spectroscopy of DNA-DAPI complexes

We discuss the use of fluorescence correlation spectroscopy for the measurement of relatively slow rotations of large macromolecules in solution or attached to other macromolecular structures. We present simulations and experimental results to illustrate the range of rotational correlation times and diffusion times that the technique can analyze. In particular, we examine various methods to analyze the polarization fluctuation data. We have found that by first constructing the polarization function and then calculating the autocorrelation function, we can obtain the rotational motion of the molecule with very little interference from the lateral diffusion of the macromolecule, as long as the rotational diffusion is significantly faster than the lateral diffusion. Surprisingly, for common fluorophores the autocorrelation of the polarization function is relatively unaffected by the photon statistics. In our instrument, two-photon excitation is used to define a small volume of illumination where a few molecules are present at any instant of time. The measurements of long DNA molecules labeled with the fluorescent probe DAPI show local rotational motions of the polymers in addition to translation motions of the entire polymer. For smaller molecules such as EGFP, the viscosity of the solution must be increased to bring the relaxation due to rotational motion into the measurable range. Overall, our results show that polarized fluorescence correlation spectroscopy can be used to detect fast and slow rotational motion in the time scale from microsecond to second, a range that cannot be easily reached by conventional fluorescence anisotropy decay methods.     

Image mean square displacement to study the lateral mobility of Angiotensin II type 1 and Endothelin 1 type A receptors on living cells

The lateral mobility of membrane receptors provides insights into the molecular interactions of protein binding and the complex dynamic plasma membrane. The image mean square displacement (iMSD) analysis is a method used to extract qualitative and quantitative information of the protein diffusion law and infers how diffusion dynamic processes may change when the cellular environment is modified. The aim of the study was to describe the membrane diffusing properties of two G‐protein‐coupled receptors namely Angiotensin II type 1 (AT₁) and Endothelin 1 type A (ET_A) receptors and their corresponding receptor–ligand complexes in living cells using total internal reflection fluorescent microscopy and iMSD analysis. This study showed that both AT₁ and ET_A receptors displayed a mix of three modes of diffusion: free, confined, and partially confined. The confined mode was the predominant at the plasma membrane of living cells and was not affected by ligand binding. However, the local diffusivity and the confinement zone of AT₁ receptors were reduced by the binding of its antagonist losartan, and the long‐range diffusion with the local diffusivity coefficient of ET_A receptors was reduced upon exposure to its antagonist BQ123. To the best of our knowledge, this is the first study addressing the protein diffusion laws of these two receptors on living cells using total internal reflection fluorescence microscopy and iMSD.     

Gold nanorods as probes in two‐photon fluorescence correlation spectroscopy: Emerging applications and potential artifacts

Owing to the highly efficient two‐photon fluorescence of gold nanorods and very short fluorescence lifetime compared with the rotational correlation time, the rotation and diffusion of a single gold nanorod can be easily observed by two‐photon fluorescence correlation spectroscopy (TP‐FCS). This property, along with the previous successful use as a contrast agent in two‐photon fluorescence imaging, suggests a potential application in TP‐FCS as well. Although the FCS measurement becomes highly efficient with gold nanorods as probes, the amplitude and temporal decay of the measured correlation functions depend critically on excitation power. Here, we investigate various photophysical processes of gold nanorods to determine the cause of such a sensitive power dependency. This understanding provides a basis for choosing appropriate FCS models to recover reasonable physical parameters. Although the correlation function amplitude G(0) is 32 times lower when the excitation power increases from 20 µW to 1.12 mW, the application of a saturation‐modified FCS model yields very good fit to each data set and the fitted concentration of 0.64 nM is comparable to the 0.7 nM given by the inductively coupled plasma mass spectrometry measurement. The FCS assay appears to be an efficient method for the quantification of gold nanorods when correctly interpreted. However, even with the saturation considered in the fitting model, the fitted rotational and translational diffusion rates are getting faster as the power increases. This indicates that other effects such as photothermal effects may raise the local temperature, and thus increasing the rotational and translational diffusion rate. Microsc. Res. Tech. 76:882–889, 2013. © 2013 Wiley Periodicals, Inc.     

Low axial drift stage and temperature controlled liquid cell for z-scan fluorescence correlation spectroscopy in an inverted confocal geometry

A recent iteration of fluorescence correlation spectroscopy (FCS), z-scan FCS, has drawn attention for its elegant solution to the problem of quantitative sample positioning when investigating two-dimensional systems while simultaneously providing an excellent method for extracting calibration-free diffusion coefficients. Unfortunately, the measurement of planar systems using (FCS and) z-scan FCS still requires extremely mechanically stable sample positioning, relative to a microscope objective. As axial sample position serves as the inherent length calibration, instabilities in sample position will affect measured diffusion coefficients. Here, we detail the design and function of a highly stable and mechanically simple inverted microscope stage that includes a temperature controlled liquid cell. The stage and sample cell are ideally suited to planar membrane investigations, but generally amenable to any quantitative microscopy that requires low drift and excellent axial and lateral stability. In the present work we evaluate the performance of our custom stage system and compare it with the stock microscope stage and typical sample sealing and holding methods.     

非色散红外气体传感器稳态扩散高斯分布浓度校正方法

流程工业中气体浓度测量至关重要。非色散红外传感器是一种基于不同气体对红外光吸收强度差异性测量气体浓度的传感器,气体浓度测量精度高,广泛用于流程工业中CO₂和N₂O气体浓度测量。非色散红外传感器内气体不均匀扩散使气体浓度测量会产生原理性误差,需要得到气体在传感器气室内达到稳态扩散时间降低浓度测量误差,提高测量精度。本文提出一种非色散红外传感器高斯分布扩散模型预测气体稳态扩散时间计算方法,14组不同条件下CO₂和N₂O的仿真实验得到本文提出高斯扩散模型的拟合度分别为0.82和0.80,验证所提出高斯模型预测气体稳态扩散时间的鲁棒性。本文所提方法非色散红外传感器浓度测量不均匀扩散产生误差补偿提供保障。     

Two-photon image correlation spectroscopy and image cross-correlation spectroscopy

We introduce two-photon image correlation spectroscopy (ICS) using a video rate capable multiphoton microscope. We demonstrate how video rate two-photon microscopic imaging and image correlation analysis may be combined to measure molecular transport properties over ranges typical of biomolecules in membrane environments. Using two-photon ICS, we measured diffusion coefficients as large as 10⁻⁸ cm² s⁻¹ that matched theoretical predictions for samples of fluorescent microspheres suspended in aqueous sucrose solutions. We also show the sensitivity of the method for measuring microscopic flow using analogous test samples. We demonstrate explicitly the advantages of the image correlation approach for measurement of correlation functions with high signal-to-noise in relatively short time periods and discuss situations when these methods represent improvements over non-imaging fluorescence correlation spectroscopy. We present the first demonstration of two-photon image cross-correlation spectroscopy where we simultaneously excite (via two-photon absorption) non-identical fluorophores with a single pulsed laser. We also demonstrate cellular application of two-photon ICS for measurements of slow diffusion of green fluorescent protein/adhesion receptor constructs within the basal membrane of live CHO fibroblast cells.     

Analysis of diffusion and binding in cells using the RICS approach

The movement of macromolecules in cells is assumed to occur either through active transport or by diffusion. However, the determination of the diffusion coefficients in cells using fluctuation methods or FRAP frequently give diffusion coefficient that are orders of magnitude smaller than the diffusion coefficients measured for the same macromolecule in solution. It is assumed that the cell internal viscosity is partially responsible for this decrease in the apparent diffusion. When the apparent diffusion is too slow to be due to cytoplasm viscosity, it is assumed that weak binding of the macromolecules to immobile or quasi immobile structures is taking place. In this article, we derive equations for fitting of the RICS (Raster‐scan Image Correlations Spectroscopy) data in cells to a model that includes transient binding to immobile structures, and we show that under some conditions, the spatio‐temporal correlation provided by the RICS approach can distinguish the process of diffusion and weak binding. We apply the method to determine the diffusion in the cytoplasm and binding of Focal Adhesion Kinase‐EGFP to adhesions in MEF cells. Microsc. Res. Tech., 2009. © 2008 Wiley‐Liss, Inc.     

虚拟转矩、转速仪的研制

分析转矩、转速测量原理，提出一种基于虚拟仪器的虚拟转矩、转速仪，通过它可方便、精确地测量转矩、转速。介绍这种虚拟转矩、转速仪的设计方法，并应用于电流变实验。实验表明：虚拟转矩、转速仪精度高、抗干扰能力强、操作简单，具有实际应用的意义。     

Transient suppression in FRF measurement: Comparison and analysis of four state-of-the-art methods

This paper compares four well selected methods for computing the non-parametric Frequency Response Function (FRF) of a periodically excited linear time invariant system. The suppression of the transient is mandatory when its influence in the data is large. Better suppression of the transient leads to a better non-parametric FRF estimate. A good non-parametric FRF estimate can be used to validate the parametric transfer function model in a second step. The suppression of the transient will be highlighted using the mean squared error of the non-parametric FRF estimate. Temperature transients caused by heat diffusion are used as example. The selected methods consist of two standard windowing methods and two methods based on the Local Polynomial Method (LPM). LPM was designed to find a non-parametric FRF estimate in the presence of nonlinearities. This paper will modify LPM to find a non-parametric FRF estimate for linear systems using a single experiment. The mean squared error of the four non-parametric FRF estimates will be compared and analyzed, based on a simulation and a measurement example.