共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
G.D. TSIBIDIS 《Journal of microscopy》2009,233(3):384-390
Fluorescence recovery after photobleaching (FRAP) measurements offer an important tool for analyzing diffusion and binding processes. Confocal scanning laser microscopes that are used in FRAP experiments bleach regions with a radially Gaussian distributed profile. Previous attempts to derive analytical expressions in the case of processes governed by fast diffusion have overlooked the characteristics of the instruments used to perform FRAP measurements and therefore led to approximating solutions. In the present paper, bleaching laser beam characteristics are incorporated into an improved model to provide a more rigorous and accurate method. The proposed model simulates binding inside bounded regions, and it leads to FRAP curves that depend on the on and off rates that can be employed to determine the rate constants. It can be used in conjunction with experimental data acquired with confocal scanning laser microscopes to investigate the biophysical properties of proteins in living cells. The model aims to improve the accuracy when determining rate constants by taking into account a more realistic scenario of the light-matter interaction. 相似文献
3.
Picart C Mutterer J Arntz Y Voegel JC Schaaf P Senger B 《Microscopy research and technique》2005,66(1):43-57
The diffusion coefficient, D, and the proportion of mobile molecules, p, is measured for a fluorescently labeled polyelectrolyte in a multilayer film using fluorescence recovery after photobleaching (FRAP). The film was composed of poly(L-lysine) (PLL) and hyaluronan (HA). The labeled polyelectrolyte (PLL(FITC)) was either deposited on top of the film or embedded within it. A circular area of diameter approximately 60 microm was bleached using a confocal laser scanning microscope. Because molecules do already diffuse during the bleaching step, the initial light intensity profile is not characteristic of a uniformly bleached circular area. A formalism is developed in which a simple mathematical representation of a measured profile serves as starting profile. This radial distribution is introduced in the equation describing the time evolution of the labeled molecule concentration under the hypothesis that the recovery results from pure, two-dimensional Brownian diffusion of the mobile molecules according to Fick's law. The analysis of a series of images taken at successive times after bleaching (up to approximately one hour) leads to estimates of D of the order of 0.2 microm(2) s(-1) for labeled molecules deposited on top of the film and a 5-fold smaller value for the molecules embedded in the film. However, p is remarkably insensitive to the position in the multilayer architecture (p approximately 0.40). 相似文献
4.
利用计算机对误差测量数据进行处理,可以提高形状和位置误差评定精度,提高数据处理速度.提出了基于分析法的按最小包容区域准则评定直线度误差和平行度误差的设计思想和基本算法,用VC 开发了误差评定软件,给出了关键部分程序代码.通过应用实例,验证了该算法的可行性和正确性. 相似文献
5.
提出了基于疏失误差的单传感器改进型分批估计数据融合算法,运用高端C8051F140型MCU的强大运算能力和丰富的外围接口电路,同时将CAN总线引入到现场数据的传输中,实现了电力变压器实时、可靠、精确的在线故障诊断。 相似文献
6.
7.
Generalized approach for accelerated maximum likelihood based image restoration applied to three-dimensional fluorescence microscopy 总被引:2,自引:0,他引:2
For deconvolution applications in three-dimensional microscopy we derived and implemented a generic, accelerated maximum likelihood image restoration algorithm. A conjugate gradient iteration scheme was used considering either Gaussian or Poisson noise models. Poisson models are better suited to low intensity fluorescent image data; typically, they show smaller restoration errors and smoother results. For the regularization, we modified the standard Tikhonov method. However, the generic design of the algorithm allows for more regularization approaches. The Hessian matrix of the restoration functional was used to determine the step size. We compared restoration error and convergence behaviour between the classical line-search and the Hessian matrix method. Under typical working conditions, the restoration error did not increase over that of the line-search and the speed of convergence did not significantly decrease allowing for a twofold increase in processing speed. To determine the regularization parameter, we modified the generalized cross-validation method. Tests that were done on both simulated and experimental fluorescence wide-field data show reliable results. 相似文献
8.
Huang Peng Huang Hong-Zhong Huang Tudi Qian Hua-Ming 《Journal of Mechanical Science and Technology》2020,34(9):3617-3627
Journal of Mechanical Science and Technology - A new structural reliability analysis framework is developed to extend the performance of first-order reliability method, which is low robustness and... 相似文献
9.
10.
Routine use of quantitative three dimensional analysis of material microstructure by in particular, focused ion beam (FIB) serial sectioning is generally restricted by the time consuming task of manually delineating structures within each image slice or the quality of manual and automatic segmentation schemes. We present here a framework for performing automatic segmentation of complex microstructures using a level set method. The technique is based on numerical approximations to partial differential equations to evolve a 3D surface to capture the phase boundaries. Vector fields derived from the experimentally acquired data are used as the driving forces. The framework performs the segmentation in 3D rather than on a slice by slice basis. It naturally supplies sub-voxel precision of segmented surfaces and allows constraints on the surface curvature to enforce a smooth surface in the segmentation. Two applications of the framework are illustrated using solid oxide cell materials as examples. 相似文献
11.
Deconvolution techniques have been widely used for restoring the 3‐D quantitative information of an unknown specimen observed using a wide‐field fluorescence microscope. Deconv , an open‐source deconvolution software package, was developed for 3‐D quantitative fluorescence microscopy imaging and was released under the GNU Public License. Deconv provides numerical routines for simulation of a 3‐D point spread function and deconvolution routines implemented three constrained iterative deconvolution algorithms: one based on a Poisson noise model and two others based on a Gaussian noise model. These algorithms are presented and evaluated using synthetic images and experimentally obtained microscope images, and the use of the library is explained. Deconv allows users to assess the utility of these deconvolution algorithms and to determine which are suited for a particular imaging application. The design of Deconv makes it easy for deconvolution capabilities to be incorporated into existing imaging applications. 相似文献
12.
A.L. PILCHAK A.R. SHIVELEY P.A. SHADE J.S. TILEY D.L. BALLARD 《Journal of microscopy》2012,248(2):172-186
A method for automatically aligning consecutive data sets of large, two‐dimensional multi‐tile electron backscatter diffraction (EBSD) scans with high accuracy was developed. The method involved first locating grain and phase boundaries within search regions containing overlapping data in adjacent scan tiles, and subsequently using cross‐correlation algorithms to determine the relative position of the individual scan tiles which maximizes the fraction of overlapping boundaries. Savitzky‐Golay filtering in two dimensions was used to estimate the background, which was then subtracted from the cross‐correlation to enhance the peak signal in samples with a high density of interfaces. The technique was demonstrated on data sets with a range of interface densities. The equations were implemented as enhancements to a recently published open source code for stitching of multi‐tile EBSD data sets. 相似文献
13.
论述了企业级组件集成框架的设计目标、设计思想和实现方案,运用可扩展标记语言描述企业级组件间的依赖关系,构建了一个能实现企业级组件即插即用的集成框架。 相似文献
14.
Dr M. Ristic D. Brujic 《The International Journal of Advanced Manufacturing Technology》1998,14(3):210-219
The paper presents an implementation of a methodology for reliable and feasible dimensional measurement of engineering components containing free-form surfaces. Two main requirements had to be satisfied. First, a large number of points had to be accurately measured. Secondly, the set of corresponding points on the nominal model had to be computed within a reasonable time. The first aspect was satisfied by adopting a non-contact measurement technique based on laser triangulation. High accuracy was achieved through software prealignment for precise component localisation and through appropriate measurement planning, both based on the CAD model. Determination of the corresponding nominal points was solved by best-fitting. Significant speed improvements were achieved through an implementation of the iterative closest point algorithm, based on a dual representation of the surface. The nominal surface is defined using NURBS entities and its approximation is determined as a polyhedral mesh. A sampling criterion for complex surfaces was derived and implemented, producing encouraging results. Validity of the proposed approach is supported by experiments and by simulation studies involving real engineering components. 相似文献
15.
一种基于网络的面向拆卸设计的评价方法 总被引:2,自引:0,他引:2
面向产品的拆卸设计是绿色设计中十分重要的研究领域。本文构建了网络环境下面向产品拆卸设计的体系结构,研究了面向拆卸设计的产品结构模型。结合Z50E装载机的具体实例,进行了产品可拆卸性的评价分析及相应的设计修改建议。 相似文献
16.
With the emergence of a global market and the recent trend of outsourcing, it is necessary for companies to have tools for remote access of data and an ability to analyze and troubleshoot manufacturing processes remotely. This need is addressed by developing an Internet-based surface texture analysis and information system, and a peer-to-peer data-sharing tool. These systems will help companies to diagnose problems related to surface texture in manufacturing process remotely. The development of the system has provided engineers from industry and academia a common framework for sharing, analyzing and storing surface texture data, analysis results, documents and reports. The system also provides a platform for quick deployment of solutions developed anywhere in the world. This paper presents the design, development and applications of a framework for surface texture analysis and information system. 相似文献
17.
面向产品的回收设计是绿色设计中十分重要的研究领域。本文构建了网络环境下面向产品回收设计的体系结构,研究了面向回收设计的回收材料选择,并确立了产品的回收分类方法。结合Z50E装载机的具体实例,进行了产品可回收性的评价分析及相应的设计修改建议。 相似文献
18.
A fast and simple algorithm for evaluation of minimum zone straightness error from coordinate data 总被引:1,自引:1,他引:1
P. B. Dhanish Jose Mathew 《The International Journal of Advanced Manufacturing Technology》2007,32(1-2):92-98
Various methods have been suggested in the past to determine the minimum zone straightness error, but suffer from various
drawbacks. A new, fast and simple algorithm is proposed to calculate the straightness error from planar coordinate data. It
guarantees the minimum zone solution. An example and test data are provided. Results of simulation experiments to establish
the time computational complexity of the algorithm are also presented. 相似文献
19.
Graphical representation and multicomponent analysis of single-frequency fluorescence lifetime imaging microscopy data 总被引:5,自引:0,他引:5
Graphical representation of fluorescence lifetime imaging microscopy data demonstrates that a mixture of two components with single exponential decays can be resolved by single frequency measurements. We derive a method based on linear fitting that allows the calculation of the fluorescence lifetimes of the two components. We show that introduction of proper error‐weighting results in a non‐linear method that is mathematically identical to a global analysis algorithm that was recently derived. The graphical approach was applied to cellular data obtained from a lifetime‐based phosphorylation assay for the epidermal growth factor receptor and yielded results similar to those obtained by a global analysis algorithm. 相似文献