Tissue shrinkage and unbiased stereological estimation of particle number and size*

This paper is a review of the stereological problems related to the unbiased estimation of particle number and size when tissue deformation is present. The deformation may occur during the histological processing of the tissue. It is especially noted that the widely used optical disector may be biased by dimensional changes in the z‐axis, i.e. the direction perpendicular to the section plane. This is often the case when frozen sections or vibratome sections are used for the stereological measurements. The present paper introduces new estimators to be used in optical fractionator and optical disector designs; the first is, as usual, the simplest and most robust. Finally, it is stated that when tissue deformation only occurs in the z‐direction, unbiased estimation of particle size with several estimators is possible.     

Influence of the number of detectors by laser scattering method for estimation of particle size

Effect of the number of detectors on an inversion problem of a scattering pattern by laser scattering method based on Mie scattering model has been investigated. The influence of the number of detectors is obtained by comparing a given size distribution and a calculated size distribution by computer simulation and experimental method. An observing range of scattering angles is from 0.0007 to 2.5 rad. A non-linear iteration method is used for calculating particle size distribution. The number of detectors is changed from 6 to 81 elements by the computer simulation. The algorithm of the inversion problem is applied with mean diameters of log-normal distribution in a range from 0.546 to 214 μm at standard deviation of 0.27 and 0.68. Experimental results of certified mono-disperse polystyrene latex standards and a poly-disperse aluminum sample are obtained with 21, 41, and 81 elements detector, respectively. All tests are performed under conditions at diluted aqueous suspensions. Narrow size distribution is influenced by the number of detectors compared with wide size distribution. Not the number of physical detectors but the number of useful detectors affects the algorithm of the inversion problem. When the detector elements are over 20, the influence of the number of detectors is decreased.     

基于粒子群的信道估计方法

针对非线性信道精确估计的问题,将随机集和粒子群理论技术应用到信道估计算法中,提出了基于离散二进制粒子群的信道估计方法,并利用Matlab对该算法进行了仿真与评价.仿真研究结果表明,该算法能够获得较为精确的信道估计,同时,该方法适用于任何能用状态空间模型以及传统卡尔曼滤波表示的非线性系统.     

Unbiased estimation of particle density in the tandem scanning reflected light microscope

The tandem scanning reflected light microscope has the property of being able to obtain information from ‘inside’ solid objects by taking a thin optical section at the focal plane of the objective lens. This plane can be focused up and down through the specimen. We describe an unbiased 3-D counting rule for the TSRLM, which is applied to the estimation of osteocyte lacunar density in whole bone. This is shown to be an extremely efficient way of making such an estimate. Further possibilities for the application of the microscope in the field of stereology are discussed.     

Volume-weighted mean particle volume estimation using different measurement methods

The use of the ‘point-sampled intercepts’ method on histopathological material is evaluated for the main purpose of comparing different methods of intercept length measurements. The volume-weighted mean nuclear volume—nuclear —of the carcinoma of the ampulla of Vater is calculated using three methods for measuring intercept lengths: a semiautomatic image analyser, an equidistant I_o-ruler and a logarithmic -ruler. Rulers of several classes and lengths are used, and the results of the nuclear estimations are compared. The equidistant I_o-ruler is more accurate than the logarithmic -ruler. With a greater number of ruler classes and with adjustment of ruler length to the greatest nuclear intercept lengths, the systematic deviation from the true value of the nuclear is smaller. The nuclear parameter has great power to differentiate intestinal carcinoma from normal tissue.     

基于粒子滤波算法的动力电池SOC估计

针对电池荷电状态(SOC)容易受到电流、温度、循环寿命等非线性因素的影响,建立基于温度和电流变化的电池容量修正方程。结合安时法和复合电化学原理构建电池状态空间模型。由于粒子滤波算法对非高斯、非线性系统的适应性,因此选用粒子滤波算法来研究电池SOC估计。通过美国FTP-75工况和NEDC工况实验仿真显示,基于粒子滤波算法的电池SOC估计比扩展卡尔曼滤波算法估计精度高、适应性好。     

Measuring absolute nanoparticle number concentrations from particle count time series

Single‐particle microscopy is important for characterization of nanoparticulate matter for which accurate concentration measurements are crucial. We introduce a method for estimating absolute number concentrations in nanoparticle dispersions based on a fluctuating time series of particle counts, known as a Smoluchowski process. Thus, unambiguous tracking of particles is not required and identification of single particles is sufficient. However, the diffusion coefficient of the particles must be estimated separately. The proposed method does not require precalibration of the detection region volume, as this can be estimated directly from the observations. We evaluate the method in a simulation study and on experimental data from a series of dilutions of 0.2‐ and 0.5‐μm polymer nanospheres in water, obtaining very good agreement with reference values.     

Quantitative analysis of particle sizes: estimation of the most efficient sampling scheme

Analysis of variance based on a hierarchical experimental design was used to establish a method finding the most economical replication schemes in quantitative television microscopy of particulates. Two products of greatly different average particle diameters and width of distributions were investigated. Error contributions were determined for each of three major steps in the procedure and smoothed curves were plotted of error v. particle size. Then cost and overall error were plotted for a variety of possible replication schemes, and a locus of best combinations drawn in. The optimal replication curve depends somewhat on the nature of the sample; thus, it is beneficial to carry out a variance analysis whenever microscopic particle size analysis is planned for a large number of samples of a new product.     

Integrated tasks assignment and routing for the estimation of the optimal number of AGVS

A fundamental problem in the management of an automated guided vehicle system (AGVS) is the determination of the load to be transported and the vehicle to transport it. The time for the loading and unloading of pallets must be specified as soon as possible. Typical objectives are minimization of travel times and costs by the reduction of the number of vehicles required to fulfill a given transportation order. This article presents a methodology for the estimation the minimum number of AGVs (considering all the available ones at the shop floor level) required to execute a given transportation order within a specific time-window. A comparison is made between the algorithms Shortest Job First and meta-heuristic Tabu Search (applied to an initial solution) for a task assignment. An enhanced Dijkstra algorithm is used for the conflict-free routing task. The number of vehicles is estimated so as to provide an efficient distribution of tasks and reduce the operational costs of the materials handling system. Simulation results of two typical industrial warehouse shop floor scenarios are provided. Although the study focuses on pre-planning of order fulfillment of materials handling, the proposed methodology can also be utilized as an important tool for investment analysis of the warehouse layout design and for estimating the ideal number of AGVs.     

基于电感式传感器的金属颗粒材质识别及粒径估计

传统的电感式颗粒传感器输出的是电感或电压幅值的脉冲信号,本质为标量信号。可通过脉冲信号的正负性区分金属颗粒是磁性或非磁性,且只能在已知颗粒材质的情况下估计颗粒的粒径。但在含有多种金属颗粒的油液中,基于标量信号的颗粒识别方法将失效。为此,本文采用了一种双锁相放大电路,将颗粒产生的复数域信号转化为一对直流信号。提出一种基于模糊隶属度函数的信号处理方法,实现了在噪音干扰下多种颗粒的材质识别和粒径估计。本文搭建了三线圈传感器实验系统。利用五种金属颗粒构建了隶属度函数,并进行系统标定。最后选取两种颗粒对标定后的系统进行了验证。结果表明系统对颗粒材质的识别准确,粒径估计误差小于2%。     

Efficient estimation of number density in opaque material microstructures: the large-area disector

Unbiased and efficient estimation of number density of features in opaque material microstructures has been quite difficult. In this contribution a montage-based efficient serial sectioning technique is presented as a practical solution for efficient estimation of number density in such microstructures. The new technique utilizes a combination of digital image analysis and unbiased disector sampling procedures.     

On the laser calibration of charged particle detectors

Problems coupled with laser reference systems of gas charged particle detectors (drift, time-projection, and streamer chambers) are considered: the physical principles of formation of laser tracks, the methods used to create thin laser beams, the characteristics of ultraviolet nitrogen lasers, etc. Examples of existing and currently being designed laser systems intended for spatial and energy calibration of the detectors are presented.     

基于粒子群优化算法的 AR模型参数估计

利用粒子群优化算法对模型AR（ P）参数进行优化,提高了模型的预测精度。采用AIC准则判断出模型的最佳阶数。该估算方法优于传统的基于最小二乘估计和基于灰色理论估计,为此类模型的参数估计提供了一种新思路。     

基于修正粒子滤波的MEMS传感器飞行器姿态解算

针对单一采用 MEMS传感器解算飞行器姿态无法克服系统非线性噪声干扰的问题,提出了一种基于修正粒子滤波的 MEMS传感器飞行器姿态解算方法.首先,利用共轭梯度法减小陀螺仪漂移误差,然后,利用加权粒子构造概率密度函数以更新粒子权值,得到优化状态估计值;再将共轭梯度法与修正粒子滤波进行融合,确定加权因子,同时以 STM32与 MEMS传感器为核心设计姿态解算系统.实验结果表明,该方法优化了飞行器静态与动态性能,姿态解算性能良好,系统过渡时间短,跟踪特性较好,且增强了系统的鲁棒性与稳定性.     

基于粒子滤波算法毫米波误差综合估计

5G毫米波通信因其高载波频率和速率而备受关注,成为了未来移动通信的研究热点。然而,在毫米波通信测试仪器设计中,通常采用多次倍频的方法为毫米波基波混频器提供毫米波本振,这个过程中附加产生的相位噪声、载波频率偏移和采样时钟偏移等误差,会造成系统解调指标恶化。为了解决这一问题,本文首次提出了一种基于粒子滤波算法的毫米波误差综合估计的方法,利用粒子滤波算法良好的鲁棒性和适应性,可一次性估计出相位噪声、载波频率偏移以及采样时钟偏移。通过仿真与实验分析,本文算法相较于传统PTRS相位噪声估计效果更好,EVM指标更优。并且本文所提算法已应用于国产5G毫米波基站综测仪中,在载波频率为28 GHz,带宽为400 MHz,调制方式为64QAM时,EVM指标可达到2.21%。     

柴油发动机超细颗粒物数量检测方法研究进展

柴油机的颗粒物排放是城市大气超细颗粒物的主要来源,对环境质量和人体健康有严重的负面影响。近年来,排放法规对颗粒物排放的控制愈加严格,并对颗粒数量测量仪器的性能提出了更高的要求。总结了5种颗粒数量测量仪器的测量原理和特点,在特定测量需求和场合下对这些设备的性能进行了对比并针对下一阶段排放法规的测量需求,分析了以上测量设备的适用性。结果表明,冷凝颗粒计数器对粒径>10 nm颗粒具有更快的响应速度,能够满足未来法规中对城市RDE测试循环的需求。然而,冷凝颗粒计数器无法测量粒径分布,不适用于针对10～23 nm颗粒控制技术的研发。但发动机排气粒度仪可给出粒径低至5.6 nm颗粒的粒径分布,可为冷凝颗粒计数器的检测结果提供补充信息。     

On semiautomatic estimation of surface area

In this paper, we propose a semiautomatic procedure for estimation of particle surface area. It uses automatic segmentation of the boundaries of the particle sections and applies different estimators depending on whether the segmentation was judged by a supervising expert to be satisfactory. If the segmentation is correct the estimate is computed automatically, otherwise the expert performs the necessary measurements manually. In case of convex particles we suggest to base the semiautomatic estimation on the so‐called flower estimator, a new local stereological estimator of particle surface area. For convex particles, the estimator is equal to four times the area of the support set (flower set) of the particle transect. We study the statistical properties of the flower estimator and compare its performance to that of two discretizations of the flower estimator, namely the pivotal estimator and the surfactor. For ellipsoidal particles, it is shown that the flower estimator is equal to the pivotal estimator based on support function measurements along four perpendicular rays. This result makes the pivotal estimator a powerful approximation to the flower estimator. In a simulation study of prolate and oblate ellipsoidal particles, the surfactor also performs well for particles which are not extremely elongated. In particular, the surfactor is not very much affected by the singularity in the surfactor formula or by possible inaccuracies in the necessary angle measurements. We also assess the performance of the semiautomatic procedure in a study of somatostatin positive inhibitory interneurons from mice hippocampi. Only 35% of the cells needed to be analysed manually and an important decrease in workload was obtained by using the semiautomatic approach.     

Estimating mean particle volume and number from random sections by sampling profile boundaries

We describe some new shape-independent stereological estimates of particle mean volume and surface area. Finding volumes or surface areas of cell nuclei, from electron micrographs of random thin sections, is a central problem of biological stereology. The well-known point-sampled intercept (PSI) method samples profile interiors to find the volume-weighted mean volume. This can be used in place of the true mean volume, but to do so introduces bias when volumes vary a great deal, as they do in fixed specimens. Jensen and Gundersen quite recently extended the PSI estimator to provide particle surface area, with no bias in the case of uniform surface areas. Here we extend the PSI volume estimator in a different way, sampling profile boundaries rather than their interiors. We obtain a boundary-sampled intercept (BSI) volume estimator, simpler than the PSI surface area estimator, but also unbiased for uniform surface areas. Both of these estimators are attractive, for example, in measuring and counting cell nuclei, where membrane surface area varies less than volume. Furthermore, they have no shape bias whatsoever. This paper also examines the general relationship between boundary- and area-sampled estimates, and we clarify the formal connection between our volume estimator and the PSI surface area estimator. We also calculate and compare their theoretical efficiencies.