The smooth fractionator

A modification of the general fractionator sampling technique called the smooth fractionator is presented. It may be used in almost every situation in which sampling is performed from distinct items that are uniquely defined, often they are physically separated items or clusters like pieces, blocks, slabs, sections, etc. To each item is associated a ‘guesstimate’ or an associated variable with a more‐or‐less close – and possibly biased ? relationship to the content of the item. The smooth fractionator is systematic sampling among the items arranged according to the guesstimates in a unique, symmetric sequence with one peak and minimal jumps. The smooth fractionator is both very simple to implement and so efficient that it should probably always be used unless the natural sequence of the sampling items is equally smooth. So far, there is no theory for the prediction of the efficiency of smooth fractionator designs in general, and their properties are therefore illustrated with a range of real and simulated examples. At the cost of a slightly more elaborate sampling scheme, it is, however, always possible to obtain an unbiased estimate of the real precision and of some of the variance components. The only real practical problem for always obtaining a high precision with the smooth fractionator is specimen inhomogeneity, but that is detectable at almost no extra cost. With careful designs and for sample sizes of about 10, the sampling variation for the primary, smooth fractionator sampling step may in practice often be small enough to be ignored.     

Precision of area estimation: a numerical study

After listing some general formulae for sampling in n-dimensional space, the author considers the one-dimensional case: the estimation of the length of a line segment by counting the number of points that happen to fall within the segment. If the points are equidistantly located, the variance of the estimate is a strictly periodic function of the length of the segment. This systematic sample has a higher efficiency than simple and stratified random samples of the same intensity. With some modifications, the results carry over to the two-dimensional case: the estimation of the area of a plane figure by counting the number of sample points falling inside the figure. However, the strict periodicity of the variance in the one-dimensional systematic case is replaced by a ‘Zitterbewegung’. The magnitude of this oscillation is seen to be very different for figures of different shapes. Some results are presented also for the estimation of areas by line transects, and for the estimation of volumes by aid of lattices of points in R³, and R⁴. Some comments are also given on the practical implications of the results for sampling in the plane.     

Estimating the total number of lymphatic valves in infant lungs with the fractionator

The fractionator is illustrated by means of a biomedical example involving the estimation of the number of lymphatic valves in lungs of infants who had died from sudden infant death syndrome (SIDS) and other known causes. The method is unbiased irrespective of tissue deformations and it does not require external information such as section thickness. An upper bound of the coefficient of error of the estimate of the number of valves within one lung was 6.5%, despite the fact that the number of valves counted per lung at the last stage ranged between 11 and 37 only. The upper bound includes the biological variation of the number of valves among infant lungs. Some theoretical remarks are also made on the efficiency of the fractionator. It is suggested, for instance, that the initial sampling stages cause more impact on the precision of the final estimator than the subsequent stages, and that an optimal arrangement of fragments submitted to systematic sampling should have the smallest fragments at the ends, with fragment contents increasing smoothly toward the middle of the series.     

Adaptive arrival cost update for improving Moving Horizon Estimation performance

Moving horizon estimation is an efficient technique to estimate states and parameters of constrained dynamical systems. It relies on the solution of a finite horizon optimization problem to compute the estimates, providing a natural framework to handle bounds and constraints on estimates, noises and parameters. However, the approximation of the arrival cost and its updating mechanism are an active research topic. The arrival cost is very important because it provides a mean to incorporate information from previous measurements to the current estimates and it is difficult to estimate its true value. In this work, we exploit the features of adaptive estimation methods to update the parameters of the arrival cost. We show that, having a better approximation of the arrival cost, the size of the optimization problem can be significantly reduced guaranteeing the stability and convergence of the estimates. These properties are illustrated through simulation studies.     

Estimation of surface area from vertical sections

‘Vertical’ sections are plane sections longitudinal to a fixed (but arbitrary) axial direction. Examples are sections of a cylinder parallel to the central axis; and sections of a flat slab normal to the plane of the slab. Vertical sections of any object can be generated by placing the object on a table and taking sections perpendicular to the plane of the table. The standard methods of stereology assume isotropic random sections, and are not applicable to this kind of biased sampling. However, by using specially designed test systems, one can obtain an unbiased estimate of surface area. General principles of stereology for vertical sections are outlined. No assumptions are necessary about the shape or orientation distribution of the structure. Vertical section stereology is valid on the same terms as standard stereological methods for isotropic random sections. The range of structural quantities that can be estimated from vertical sections includes V_v, N_v, S_v and the volume-weighted mean particle volume v?_v, but not L_v. There is complete freedom to choose the vertical axis direction, which makes the sampling procedure simple and ‘natural’. Practical sampling procedures for implementation of the ideas are described, and illustrated by examples.     

A simple and efficient alternative to implementing systematic random sampling in stereological designs without a motorized microscope stage

When properly applied, stereology is a very robust and efficient method to quantify a variety of parameters from biological material. A common sampling strategy in stereology is systematic random sampling, which involves choosing a random sampling relevant objects start point outside the structure of interest, and sampling at sites that are placed at pre‐determined, equidistant intervals. This has proven to be a very efficient sampling strategy, and is used widely in stereological designs. At the microscopic level, this is most often achieved through the use of a motorized stage that facilitates the systematic random stepping across the structure of interest. Here, we report a simple, precise and cost‐effective software‐based alternative to accomplishing systematic random sampling under the microscope. We believe that this approach will facilitate the use of stereological designs that employ systematic random sampling in laboratories that lack the resources to acquire costly, fully automated systems.     

一种基于视觉注意力的快速运动估计算法

运动估计在视频编码中占据十分重要的地位,因为它能有效地去除图像序列的时域冗余,大大提高编码效率,但往往算法复杂,占用整个编码过程较多的时间.针对智能视频监控等领域的应用,提出一种基于视觉注意力的快速运动估计算法.该算法的核心思想是利用视觉注意力模型将关注的运动区域提取出来作为显著性区域,然后利用快速运动估计算法在显著性区域采用较高的预测精度,而非显著性区域采用较低的预测精度.实验结果表明在峰值信噪比几乎不变的情况下,该算法比其他经典运动估计算法的运算时间有明显减少.     

A Bayesian paradox and its impact on the GUM approach to uncertainty

The paper presents ideas and observations about the use of the frequentist and the Bayesian approach to estimation and uncertainty. The merits and the pitfalls of the Bayesian approach, compared with the frequentist one, are illustrated using a simple example, which gives rise to an instructive paradox. The impact of the paradox on the GUM approach to uncertainty prescribed in Supplement 1 is highlighted and discussed.     

RFID-enabled tracking in flexible assembly line

Radio frequency identification (RFID) technology provides a wireless means to detect and identify objects. By using RFID reader as detecting sensor, an RFID-assisted object tracking system is developed to track the object movement for a flexible manufacturing assembly line. Both range-based and range-free cooperative object tracking algorithms are analyzed for the system. And to achieve tradeoff between the reader plate’s density and cost, only simple readers with omnidirectional aerial are considered in this article. To further enhance the assembly line efficiency, a particle filter model is developed to further process the object tracking results to improve the tracking accuracy. The proposed tracking system can also forecast the movement state of objects in the assembly lines.     

On the empirical variance of a fractionator estimate

The fractionator consists of several sampling stages with systematic sampling at each stage; data are collected only at the last stage. Therefore, predicting the error variance of a fractionator estimator is a non-trivial problem, because the observations are correlated in a complicated, unknown way. Gundersen proposed to split the material sampled at the first stage into two subsets, and to compute the variance of the pooled estimate empirically using the corresponding pair of observations made in these two subsets. The idea is very effective, but the estimator thus proposed needed some corrections. The purpose of this paper is to present an improved estimator of the coefficient of error of a fractionator estimator using Gundersen's design.     

Design solution evaluation for metal forming product development

In the current metal forming product development paradigm, the simultaneous and optimal design of product, process and forming system is a non-trivial issue as there are many affecting factors which interact and interplay each other. In the up-front design process, the systematic evaluation and verification of design solution is critical as this could shift the product development paradigm from traditionally trial-and-error and heuristic know-how to more scientific calculation, analysis and simulation. To ensure the efficient and accurate assessment and evaluation of design solution generation, state-of-the-art technologies need to be developed. In this paper, a methodology for systematic evaluation and verification of the simultaneous design of metal forming product, process, and forming system is presented. The factors which affect these designs are first articulated and how they interact and interplay are described. The importance of the systematic evaluation of designs is, thus, figured out. In addition, the role that CAE simulation plays in this process is explained. To evaluate the design, detailed evaluation criteria are developed and how the criteria are used through CAE simulation technology to reveal the behaviors and performances of designs is articulated. Through case studies, the developed technology is illustrated and its efficiency is finally verified.     

An accurate and economical approach for induction motor field efficiency estimation using bacterial foraging algorithm

As the demand of electrical energy increases, it is vital to replace inefficient motors with new energy efficient ones. The first step towards achieving this goal is to estimate the existing motors efficiencies accurately to determine how much energy saving will be achieved by using energy efficient motors. This paper proposes an economical and accurate approach for motor field efficiency estimation using bacterial foraging algorithm. The approach relies on the measurement of the stator current, stator voltage, input power, stator resistance and rotor speed of the motor without conducting no-load and locked-rotor tests. The BF algorithm is used to determine the equivalent circuit parameters of the motor. The efficiency is then estimated using these parameters. The advantages of the proposed method over the existing methods are simple procedure, efficiency can be estimated accurately without conducting any invasive tests and inexpensive. The approach has been tested on a 5 HP motor and the results are compared with particle swarm optimization method, immune algorithm method, torque gauge method, equivalent circuit method, slip method, current method and segregated loss method. The results demonstrate that the proposed approach can accurately estimate the field efficiency of motor. Accordingly, it is suitable for conducting energy audits and management of the motor.     

基于编码对象模型的自动查重与赋码算法研究与应用

从编码对象域和编码粒度等方面,系统研究了"编码对象模型"的概念及其关键点,提出了基于编码对象模型的批量数据自动查重、相似度约束查重和自动赋新码的算法。这些算法在信息编码管理平台中的应用表明,能大幅度提高查重与赋码的工作效率。     

视觉伺服机器人打击运动目标的轨迹规划

讨论了视觉伺服机器人在打击运动目标时的轨迹规划问题,提出了一种在平面上打击运动目标的方案,包括目标运动参数估计算法、目标跟踪和接近的算法.这种方案适用于打击近似作直线运动目标的轨迹规划.最后给出了一些仿真结果.     

Non‐uniform systematic sampling in stereology*

Non‐uniform systematic sampling designs in stereology are studied. Various methods of constructing non‐uniform systematic sampling points from prior knowledge of the measurement function are presented. As an example, we consider area estimation from lengths of linear intercepts. The efficiency of two area estimators, based on non‐uniform sampling of parallel lines, is compared to that of the classical 2D Cavalieri estimator, based on uniform sampling, in a sample of planar profiles from transverse sections of 41 small myelinated axons. The comparison is based on simulations. It is concluded that for profiles of this type one of the non‐uniform sampling schemes is more efficient than the traditional uniform sampling scheme. Other examples where non‐uniform systematic sampling may be used are in area estimation from lines emanating from a fixed point, area estimation from concentric circles or spirals and curve length estimation from sweeping lines. It is shown that proportional‐to‐size sampling is a special case of non‐uniform systematic sampling. Finally, the effect of noise in the observations is discussed.     

Peculiarities of imaging one- and two-dimensional structures using an electron microscope in the mirror operation mode

Measurements performed in an electron microscope with the mirror operation mode are most sensitive to local electric fields and geometrical roughness of any kind of the object being studied. The object with a geometrical relief is equivalent to a smooth surface with an effective distribution of microfields. Electrons forming the image interact with the local microfields for an extended time: during approach to the object, deceleration and acceleration away from the object. As a result, the electron trajectories can be strongly distorted, and the contrast changes essentially, leading to image deformation of details of the object under investigation and to lowering of the resolution. These effects are theoretically described and are illustrated by experiments. An analysis of these effects enables the real size and the shape of the object involved to be reconstructed.     

Software sensors for bioprocesses

State estimation is a significant problem in biotechnological processes, due to the general lack of hardware sensor measurements of the variables describing the process dynamics. The objective of this paper is to review a number of software sensor design methods, including extended Kalman filters, receding-horizon observers, asymptotic observers, and hybrid observers, which can be efficiently applied to bioprocesses. These several methods are illustrated with simulation and real-life case studies.     

A simple and effective setup for in situ investigations of the surface magnetooptic Kerr effect in ultrahigh vacuum

A simple and inexpensive device rather sensitive to studies of magnetic properties of very thin (0.5–0.6 nm) ferromagnetic films by the surface magnetooptic Kerr effect (SMOKE) method in ultrahigh vacuum (UHV) conditions is described. The system is intended for measuring both longitudinal and transversal Kerr effects. The special vacuum-tight electromagnet system of the SMOKE device is quite compatible with other surface-sensitive methods. When an additional external magnet system is used, the same optical and electronic system can be also employed for ex situ investigations. Examples demonstrating the high sensitivity of this setup and its efficiency during studies of the magnetic anisotropy are given.