The Design, Construction, and Performance of a Cesium-Beam Tube

A discussion of salient aspects of the design, construction, and performance of the National Research Council 2.1-meter cesium-beam frequency standard is presented. Emphasis is placed on the characteristics of the cesium (F = 4)?(F = 3) ? transitions as they are affected by a range of microwave power and weak dc-magnetic C-field intensities. The technique of C-field determination based on excitation of the (4, -4)?(4, -3) transition is described.     

Development of an optically pumped Cs frequency standard at theNRLM

Describes development of an optically pumped Cs frequency standard aiming at a primary frequency standard. Using this laboratory-type standard, a Ramsey resonance spectrum was observed. It has been shown that a laser power of about 1 mW is almost sufficient for two-frequency optical pumping. It has also been shown that the C-field strength can be measured using Zeeman coils by establishing a population difference among the Zeeman sublevel with σ⁺ polarized laser light     

High-stability current control in the 10 A range

This paper reports on the design and evaluation of a high-stability current control developed for energizing the C-field magnet of the high-field cesium standard experiment, currently in progress at the Politecnico di Torino. This source must supply about 0.8 kW dc power with a current stability in the 10^-7 range for more than 1 h     

New design for a high performance optically pumped cesium beam tube

An optically pumped cesium beam resonator has been designed including three successive magnetic field regions. The optical interactions take place in the first and third regions, where the magnetic field has the required value of 3x10(-5) T. The microwave interaction occurs in the intermediate region, where the value of the C-field is typically set to 4x10(-6) T. It has been verified that the magnetic field profile along the cesium beam does not induce Majorana transitions. Using a single laser diode emitting at 852 nm with a linewidth of about 30 MHz, the resonator gives an excellent amplitude signal to noise ratio equal to 20000 in a 1-Hz bandwidth.     

Design of and Preliminary Results on a Cesium-Beam Standard at the Radio Research Laboratories

A laboratory type cesium beam standard is being constructed for experimental use as a working standard at the RRL of Japan. Ihe structural design and experimental results on the phase adjustment of Ramsey cavity, the beam optics employing hexapole magnets, and an axial C-field, and the digital servo system are described. Methods for evaluating the beam velocity distribution employing a pulse technique and the analysis of the Ramsey pattern are examined. Observed intensity of Ramsey signal proved satisfactory, and other experiments are now proceeding.     

Globalization technique for projected Newton–Krylov methods

Large‐scale systems of nonlinear equations appear in many applications. In various applications, the solution of the nonlinear equations should also be in a certain interval. A typical application is a discretized system of reaction diffusion equations. It is well known that chemical species should be positive otherwise the solution is not physical and in general blow up occurs. Recently, a projected Newton method has been developed, which can be used to solve this type of problems. A drawback is that the projected Newton method is not globally convergent. This motivates us to develop a new feasible projected Newton–Krylov algorithm for solving a constrained system of nonlinear equations. Combined with a projected gradient direction, our feasible projected Newton–Krylov algorithm circumvents the non‐descent drawback of search directions which appear in the classical projected Newton methods. Global and local superlinear convergence of our approach is established under some standard assumptions. Numerical experiments are used to illustrate that the new projected Newton method is globally convergent and is a significate complementarity for Newton–Krylov algorithms known in the literature. © 2016 The Authors. International Journal for Numerical Methods in Engineering Published by John Wiley & Sons Ltd.     

Absolute phase measurements using geometric constraints between multiple cameras and projectors

The method of phase shift with the projection of multiple cyclic patterns enables 3D measurement that is highly accurate, dense, and fast. However, this measurement is only possible for the wrapped phase value, which has ambiguities in its multiples of cycles. Two particular problems are that conventional methods require additional patterns to be projected to determine the absolute phase and that unwrapping the phase tends to fail where depth varies abruptly. Two methods are proposed: the first is to determine the absolute phase without additional patterns being projected by observing the projected pattern with multiple cameras and applying the geometric constraints between them, and the second is to prevent failure in unwrapping the phase by referring to continuities in the relative phases of multiple projected patterns. The proposed methods were achieved with a 3D scanner that can measure approximately a 180 degrees field of view within 0.5 s, with an accuracy of 0.14 mm in depth.     

Average lattices and aperiodic structures

Statistically averaged lattices provide a common basis to understand the diffraction properties of structures displaying deviations from regular crystal structures. An average lattice is defined and examples are given in one and two dimensions along with their diffraction patterns. The absence of periodicity in reciprocal space corresponding to aperiodic structures is shown to arise out of different projected spacings that are irrationally related, when the grid points are projected along the chosen coordinate axes. It is shown that the projected length scales are important factors which determine the existence or absence of observable periodicity in the diffraction pattern more than the sequence of arrangement.     

用投影轮廓分维中位维表征颗粒群粗糙度的研究

为了表征颗粒群粗糙度,本文中构建了单颗粒投影轮廓分维数学模型,并以高精度数字光学显微系统为基础,测算了5种颗粒样品的单颗粒投影轮廓分维。结果表明,5种颗粒样品的单颗粒投影轮廓分维均值从小到大依次为:柴油汽车排气管沉积颗粒、碳黑颗粒、粉煤灰颗粒、石灰性褐土颗粒、河流沉积土壤颗粒。首次提出了"中位维"的概念以表征颗粒群粗糙度,计算了颗粒样品的中位维,其大小排序与投影轮廓分维均值一致,验证了将"中位维"作为表征颗粒群粗糙度的合理性。     

Errors in the Estimation of the Activation Energy and the Projected Shelf Life in Employing an Incorrect Kinetic Order in an Accelerated Stability Test

The errors involved in the estimation of the activation energy of the drug degradation and the projected shelf life of a drug product when employing an incorrect kinetic order in the accelerated stability test were analyzed. The activation energy of a zero order degradation and the projected shelf life of a drug product are overestimated when the kinetic data are treated in first order fashion. The overestimation in the activation energy increases with the temperature range of the accelerated test and the instability of the drug. The over-estimation in the projected shelf life increases with the activation energy and increases as the normal     

反向条纹投影技术及其在数字地球仪中的应用

本文提出一种基于反向条纹投影原理的数字地球仪.在数字地球仪中,显示屏是一个球面的漫反射屏,通过投影的方法可以实现数字地球仪任意方向的旋转显示.首先通过投影正弦条纹到球面显示屏上,从观察数字地球仪的方向用CCD相机获取变形条纹图像,通过相移算法,建立投影器和摄像机像素之间的几何传递关系.基于地球三维图形信息数据库,根据期望图像为投影器产生投影图像.本文建立了地球三维信息提取模型,可快速获取从任意角度观察地球的图形信息.实验使用一半径为25 cm的漫反射球体作为显示屏,将计算得到反向地图投影其上,得到相当好的实验结果.     

Three-dimensional measurement and imaging based on multicameras randomly distributed on the circumference

We present a three-dimensional (3D) measurement and imaging based on a multicamera system. In the presented system, projected images of 3D objects are taken by cameras located at random positions on a circumference, and then the 3D objects can be reconstructed numerically. We introduce an angle correction function to improve the quality of the reconstructed object. The angle correction function can correct the angle error caused by the position errors in the projected images due to the finite pixel size of the image sensor. The numerical results show that the point source was reconstructed successfully by introducing the angle correction function. We also demonstrate experiments: the two objects are located on a rotary stage controlled by a computer, the projected images are taken by a single camera, and by using 33 projected images, the two objects are reconstructed successfully.     

Three-dimensional profilometry based on shift estimation of projected fringe patterns

This paper presents a new approach to fringe pattern profilometry. In this paper, a generalized model describing the relationship between the projected fringe pattern and the deformed fringe pattern is derived, in which the projected fringe pattern can be arbitrary rather than being limited to being sinusoidal, as are those for the conventional approaches. Based on this model, what is believed to be a new approach is proposed to reconstruct the three-dimensional object surface by estimating the shift between the projected and deformed fringe patterns. Additionally, theoretical analysis, computer simulation, and experimental results are presented, which show how the proposed approach can significantly improve the measurement accuracy, especially when the fringe patterns are distorted by unknown factors.     

Predicting lifetime by degradation tests: A case study of ISO 10995

ISO 10995 is the international standard for the reliability testing and archival lifetime prediction of optical media. The standard specifies the testing conditions in terms of the combinations of stress variables—temperature and relative humidity. The periodically collected data from tests are the error rate of the device, and failure is defined as the error rate exceeding a predetermined level. The standard assumes that the projected failure time is the actual failure time, and these projected failure times are then analyzed by using an Eyring or Arrhenius model. Since true failure times are often not directly observed, the uncertainties in the failure time must be taken into account. In this paper, we present a hierarchical model for degradation that can directly infer failure time at the use condition and compare this model with the International Standard Organization (ISO) standard through a simulation study. Not accounting for the uncertainty in the projected failure times leads to unjustified confidence in the estimation for the median lifetime at both the stress conditions used in the experiments and at the use condition.     

The 44th Physical Society Exhibition

Data are presented on the dimensional characteristics of relief images on a reversal colour material (Kodachrome II Film) and their connection with image density. From simple theoretical consideration it is deduced that the relief image may have a significant influence on the definition ofa projected image, but that the magnitude of this contribution will be strongly dependent on the half-angles of illumination and collection in the projection system.

Various demonstrations are presented showing that the relief image can make an appreciable contribution to the definition for rather more specular conditions of illumination and collection than are used in conventional transparency projectors. However, this is only readily apparent when the projected image subtends a much larger angle than is regularly used in viewing. For angles of illumination and collection used in a transparency projector the effects of a relief image on a 24 x 36 mm transparency on the definition of the projected image are just detectable at viewing distances such that the image subtends about four times the normal angle, but not at normal viewing distances.

Even under circumstances such that the relief image has a considerable influence on definition, image elements away from the centre of the field exhibit asymmetrical halo effects. In general, these effects would be regarded as objectionable. Moreover, the increase in definition in the centre of the field obtained by use of a relief image may be accompanied by a general increase in graininess into the projected image.

The overall conclusion is that under normal conditions relief Images make only a small contribution to the definition of projected images of 24 x 36 mm transparencIes, and that, 10 general, the advantages resulting from a major contribution of the relief image are more than outweighed by the disadvantages.     

一种基于三维模型投影的人脸识别新方法

研究了使用三维人脸模型进行不同姿势下的人脸识别问题,提出了一种三维建模二维识别的人脸识别算法,首先使用该方法将三维模型向不同方向投影,进而将不同姿势的二维图像与不同方向的投影结果相匹配,进行人脸识别。研究了使用Minolta Vivid 910进行数据获取,创建三维模型的方法和过程。实验结果表明,在进行不同姿势的人脸识别时,该方法的识别速度快于三维可变形模型方法,识别率远优于使用二维正面图像作为模板的人脸识别方法。     

Deconvolution of axisymmetric flame properties using Tikhonov regularization

We present a method based on Tikhonov regularization for solving one-dimensional inverse tomography problems that arise in combustion applications. In this technique, Tikhonov regularization transforms the ill-conditioned set of equations generated by onion-peeling deconvolution into a well-conditioned set that is less susceptible to measurement errors that arise in experimental settings. The performance of this method is compared to that of onion-peeling and Abel three-point deconvolution by solving for a known field variable distribution from projected data contaminated with an artificially generated error. The results show that Tikhonov deconvolution provides a more accurate field distribution than onion-peeling and Abel three-point deconvolution and is more stable than the other two methods as the distance between projected data points decreases.     

Lattice Distortion Analysis Directly from High Resolution Transmission Electron Microscopy Images—the LADIA Program Package

Direct strain mapping from high resolution transmission electron microscopy images is possible for coherent structures.At proper imaging conditions the intensity peaks in the image have a constant spatial relationship with the projected atom columns.This allows the determination of the geometry of the projected unit cell without comparison with image simulations.The fast procedure is particularly suited for the analysis of large areas.The software package LADIA is written in the PV-WAVE code and provides all necessary tools for image processing and analysis.Image iintensity peaks are determined by a cross-correlation technique,which avoids problems from noise in the low spatial frequency renage.The lower limit of strain that can be detected at a sampling rate of 44 pixels/nm is ≈2%.     

烧结颈分布对3D打印覆膜Al2O3零件强度的影响

从烧结颈的尺寸及分布入手,研究覆膜Al2O3粉末的粒径分布对零件强度的影响。使用UV激光对覆膜粉末进行原位加热,在影像测量仪下测量并获得烧结颈束腰直径与颗粒直径之间的关系。建立颗粒堆积模型,将烧结颈分布与颗粒配位点对应,计算得出某一截面上被断开的烧结颈的投影面积比例。结果表明:对于2%(质量分数)树脂含量的覆膜Al2O3粉末,随着颗粒直径从75μm增长至375μm,烧结颈的束腰直径从40μm增长至100μm。而堆积模拟结果显示,随着颗粒直径从75~107μm区间增加至300~375μm区间,烧结颈的投影面积比例从0.2557降低至0.0823,与实验测量的覆膜Al2O3粉末的抗拉强度的趋势一致。将70/100,100/140目的颗粒按照质量比0∶10,1∶9,2∶8,3∶7,4∶6,5∶5,6∶4,7∶3,8∶2,9∶1,10∶0混合后计算,发现投影面积比例从0.1772降低至0.1264,孔隙率从0.4511升高至0.4633。综合考虑抗拉强度及透气性,得出优化结果为两者比例为7∶3时,投影面积比为0.1481,堆积孔隙率为0.4596。     

A Study of the Swelling of Tablet Excipients Using Video Recording

Abstract

A video recording technique was used to study microscopically the svelling characteristics of individual tablet disintegrant particles in vater. Feret's diameter, projected area and dimensionless shape factors such as elongation ratio, bulkiness factor and surface factor of various particle profiles were determined. Hydrated particles of cross-linked sodium cazboxymethylcellulose (Ac-Di-Sol) and loW substituted sodium carboxymethylcellulose (Nymcel ZSB10 and ZSD16) had high Feret's diameter and projected areas. Swelling in their case vas due to the hydration of macromolecules. Hydrated microcrystalllne CellUlOSe (Avicel PHlOll partlcles had a narrov distribution of both Feret's diameter and projected area. The lov degree of svelling In these particles vas due to entry of vater into particle pores. Fibrous particles of Nymcel ZSB10 retained their elongated shape even after swelling fully. Ac-Di-Sol and Nymcel ZSD16 particles hovever svelled appreciably along their breadth also and assumed a less elongated profile than vhen dry. The order for increase in projected area diameter after hydration was Ac-Di-Sol > Nymcel ZSB10 > ZSD16 > Avicel PH101.