Aspects regarding measurement of thickness of intergranular glassy films

Materials such as Si₃N₄, SiC and SrTiO₃ can have grain boundaries characterized by the presence of a thin intergranular amorphous film of nearly constant thickness, in some cases (e.g. Si₃N₄) almost independent of the orientation of the bounding grains, but dependent on the composition of the ceramic. Microscopy techniques such as high‐resolution lattice fringe imaging, Fresnel fringe imaging and diffuse dark field imaging have been applied to the study of intergranular glassy films. The theme of the current investigation is the use of Fresnel fringes and Fourier filtering for the measurement of the thickness of intergranular glassy films. Fresnel fringes hidden in high‐resolution micrographs can be used to objectively demarcate the glass–crystal interface and to measure the thickness of intergranular glassy films. Image line profiles obtained from Fourier filtering the high‐resolution micrographs can yield better estimates of the thickness. Using image simulation, various kinds of deviation from an ideal square‐well potential profile and their effects on the Fresnel image contrast are considered. A method is also put forth to objectively retrieve Fresnel fringe spacing data by Fourier filtering Fresnel contrast images. Difficulties arising from the use of the standard Fresnel fringe extrapolation technique are outlined and an alternative method for the measurement of the thickness of intergranular glassy films, based on zero‐defocus (in‐focus) Fresnel contrast images is suggested. The experimental work is from two ceramic systems: Lu‐Mg‐doped Si₃N₄ and SrTiO₃ (stoichiometric and nonstoichiometric). Further, a comparison is made between the standard high‐resolution lattice fringe technique, the standard Fresnel fringe extrapolation technique and the methods of analyses introduced in the current work, to illustrate their utility and merits. Taking experimental difficulties into account, this work is intended to be a practical tool kit for the study of intergranular glassy films.     

Empirical estimation of the ERS-1 SAR radiometric resolution

This letter describes a technique to evaluate the radiometric quality of distributed target responses extracted from Synthetic Aperture Radar (SAR) data. The approach is original in that it aims to estimate the Equivalent Number of Looks of clustered pixels, a parameter which summarizes the first order statistics of speckle. This empirical method can be applied to processed, interpolated, and even speckle-filtered, SAR images. Using ERS-1 Precision Image SAR data, it is shown, first, how to discriminate between uniform and non-uniform targets, and, then, to estimate the radiometric resolution of pixels gathered according to several clustering schemes.     

Inline electron holography and VEELS for the measurement of strain in ternary and quaternary (In,Al,Ga)N alloyed thin films and its effect on bandgap energy

We present the use of (1) dark‐field inline electron holography for measuring the structural strain, and indirectly obtaining the composition, in a wurtzite, 4‐nm‐thick InAlGaN epilayer on a AlN/GaN/AlN/GaN multinano‐layer heterosystem, and (2) valence electron energy‐loss spectroscopy to study the bandgap value of five different, also hexagonal, 20–50‐nm‐thick InAlGaN layers. The measured strain values were almost identical to the ones obtained by other techniques for similarly grown materials. We found that the biaxial strain in the III‐N alloys lowers the bandgap energy as compared to the value calculated with different known expressions and bowing parameters for unstrained layers. By contrast, calculated and experimental values agreed in the case of lattice‐matched (almost unstrained) heterostructures.     

正负交替反转法解析电子衍射相位问题

与X射线晶体学中存在的相位问题类似,在电子衍射中也存在相位问题:在电子衍射实验中只能收集到衍射强度而丢失了相位.最近,衍射重构成像方法(diffractive imaging),即直接从衍射重构出晶体结构的方法,从理论和实验都有了重大进展.从理论上,人们提出和发展许多有效的相位解析方法.从实验上,高强度的X射线源,场发射电子枪以及高灵敏度的记录媒介的发展都对此有贡献.直接从衍射重构出晶体结构有许多的优点:首先在重构像中,物镜球差的影响很小.这是由于物镜传递函数对衍射强度的影响远远小于对相位的影响;其次,从同一晶体收集的电子衍射有更多的高阶衍射斑,使得衍射重构能得到较高的分辨率(小于0.1 nm);同时,在同样辐射条件下晶体的电子衍射比其高分辨像具有更高的信噪比.这对于用电镜解析对辐射损伤敏感的有机物和生物蛋白晶体是有用的.本文叙述了一个解决电子衍射相位的新方法.在本文的程序中,同时使用了Oszlányi和Süto提出的正负交替反转法(charge-flipping algorithm)和Fienup的重构方法(hybrid input-output algorithm).作者用模拟数据来验证该方法的有效性.在程序中输入计算的运动学电子衍射强度,模拟晶体的二维静电势场分布能被重构出来.使用归一化结构因子可以提高正空间的重构像衬度;这对解决相位问题是有利的.使用Fienup的重构方法可以有效地解决由局域最小值而引起程序停滞问题.在正负交替反转法中通常会有停滞问题而不能找到全局最小值.正负交替反转法会逐步地在正空间中产生较大的零值电势区域,从而减小了正空间中未知数的数目.当未知数数目小于或等于从傅立叶变换建立起来的等式数目时,晶体的相位就可以解决了.     

Incorporating L-Ascorbyl 6-Palmitate in Bread and Its Shortening-Sparing and Anti-Firming Effects

L-Ascorbyl 6-palmitate (AP) was conveniently incorporated in bread dough by gently premixing AP in vegetable oil or shortening, adding the premix with the remaining ingredients and mixing the dough at conventional speeds. Alternatively, high-speed mixing of AP with formula flour or water also gave fully functional AP in bread doughs as evidenced by complete shortening replacement at 0.38% AP (based on flour weight) and by the absence of dark specks on the crust of bread. Compared to a mixture of 0.38% AP and 3% shortening or a mixture of 0.5% monodiglycerides and 3% shortening, AP alone at 0.38% in bread gave softer crumb after 1 to 5 days storage at 25°C. Sodium stearoyl 2-lactylate (SSL) at 0.38% gave the same softening effect as AP. In no-shortening loaves, 0.38% AP gave better grain than 0.75% L-ascorbyl 6-octanoate or 0.50% L-ascorbyl 6-dodecanoate.     

THYRISTOR CONTROLLED PULSATING FIELD RELUCTANCE MOTOR SYSTEM

ABSTRACT

Integral horsepower pulsating field reluctance motors are treated when operating in dc-supplied, fixed voltage, thyristor controlled variable speed systems. A thyristor controller with two operating modes is described. Exciting MMF differential equations are put into normalized forms, simplifying their solutions, which are given. Three parameters Q, p and x_rs concisely character= rize motor, MMF differential equations and torque. For typical speed/torque curves thyristor control angles are determined. Optimum pole- and gap dimensions are investigated on the basis of published permeance charts.     

Radiometric comparison of the LANDSAT-5 TM and MSS sensors

Abstract

This paper analyses the radiometric accuracy of LANDSAT-5 Thematic Mapper (TM) data and of LANDSAT-5 Multispectral Scanner (MSS) data, using concurrent TM and MSS images recorded simultaneously over the city of Montreal, Quebec, Canada. The data sets were obtained from the Canada Centre for Remote Sensing (CCRS), and have been preprocessed for geometric correction, and for radiometric 23calibration utilizing the in-flight calibration lamp data. The comparison of the TM and MSS normalized apparent reflectances computed for 12 different typical cover types using the post-launch calibration dynamic ranges shows the relevance of the CCRS processing systems. The significant linear regressions, obtained between channels from the two sensors, and the analysis of the ground reflectance corrected for atmospheric absorption and scattering as well as for pixel adjacency effects, can serve both to assess detector degradation with time and to rescale data to match those from other LANDSAT sensors.     

Automatic map-guided extraction of roads from SPOT imagery for cartographic database updating

Abstract

The launching of the Satellite Probatoire d'Observation de la Terre (SPOT) has permitted the acquisition of images with a relatively fine ground resolution (10 and 20 m). Such improvement has brought forward the possibility of medium-scale mapping using such data. In this paper we are proposing an automatic approach to 1:50000 scale planimetric data revision using the panchromatic channel of SPOT imagery (10m of ground resolution). A software package has been developed that performs an automatic map-guided extraction of objects from the SPOT image for map revision purposes. The programs are fully described along with some conclusive results through the updating of the road network on a topographic map. An attempt has been made to give a preview of how such a map-guided approach can be extended to other linear features and possibly two-dimensional objects as well.     

COLLAGEN CHARACTERISTICS AND MEAT TEXTURE OF PIGS EXPOSED TO DIFFERENT LEVELS OF PHYSICAL ACTIVITY

Intramuscular collagen and meat texture were measured in 23 female and 23 entire male pigs, subjected to one of three treatments: individual housing in pens of 2.5 m² (confined; C), individual housing and regular treadmill training (trained; T) and group housing equal to 0.9 m²/animal (free; F).
Treatment T tended (P = 0.13) to increase the activity of citrate synthase (CS) in M. biceps femoris (BF) from female pigs. Moreover, the heat stability of collagen and the mechanical resistance to 60 and 80% compression were increased (P<0.03) in BF from female pigs in treatments T and F as compared to C. In BF from male pigs, treatment T decreased (P = 0.03) the heat stability of collagen when compared to C and F. Sensory tenderness was not affected (P>0.05) by physical activity, however. In BF from female pigs, CS activity, collagen content and resistance to compression were lower (P<0.01) than in male pigs. In M. longissimus thoracis et lumborum, there was no effect of either physical activity or sex. Depending on muscle type and sex, physical activity affects meat texture.