Automation of white light photoelasticity by phase-shifting technique using colour image processing hardware

The early application of the digital image processing (DIP) technique to automate photoelastic analysis is based on black and white image processing systems. The various methodologies reported can be said to rely upon one or more features of a black and white DIP system. With the advancements in computer technology, modern colour image processing systems are available at affordable prices. In such systems, the image is identified as a superposition of image planes of red, green and blue. This paper investigates whether one or all of the image planes can be thought of as behaving like an optical filter: with the hardware used, the green channel is found to behave in this way. This idea is then used to extend the phase-shifting technique to colour domain. For the problem of a disk under diametral compression, total fringe order variation along a few lines is evaluated by this new technique and compared with theoretical predictions: the comparison is found to be good.     

Point-wise and whole-field laser speckle intensity fluctuation measurements applied to botanical specimens

Based on multi-scattering speckle theory, the speckle fields generated by plant specimens irradiated by laser light have been studied using a pointwise method. In addition, a whole-field method has been developed with which entire botanical specimens may be studied. Results are reported from measurements made on tomato and apple fruits, orange peel, leaves of tobacco seedlings, leaves of shihu seedlings (a Chinese medicinal herb), soy-bean sprouts, and leaves from an unidentified trailing houseplant. Although differences where observed in the temporal fluctuations of speckles that could be ascribed to differences in age and vitality, the growing tip of the bean sprout and the shihu seedling both generated virtually stationary speckles such as were observed from boiled orange peel and from localised heat-damaged regions on apple fruit. Our results suggest that both the identity of the botanical specimen and the site at which measurements are taken are likely to critically affect the observation or otherwise of temporal fluctuations of laser speckles.     

Practical colour management

Spectrophotometers have been successfully used for colour measurement. This paper addresses digital imaging as a complementary and alternative method of colour measurement and appearance and an effective communication tool as part of a practical colour management programme within the supply chain of a textile retailer. The specific needs—to measure and communicate textured dyed material and printed fabric—are discussed, as well as the colour specification and quality control (QC) of currently un-measurable fabrics and accessories. A unique method of using digital imaging for the assessment of colour fastness will also be discussed.     

Some Information Geometric Aspects of Cyber Security by Face Recognition

Secure user access to devices and datasets is widely enabled by fingerprint or face recognition. Organization of the necessarily large secure digital object datasets, with objects having content that may consist of images, text, video or audio, involves efficient classification and feature retrieval processing. This usually will require multidimensional methods applicable to data that is represented through a family of probability distributions. Then information geometry is an appropriate context in which to provide for such analytic work, whether with maximum likelihood fitted distributions or empirical frequency distributions. The important provision is of a natural geometric measure structure on families of probability distributions by representing them as Riemannian manifolds. Then the distributions are points lying in this geometrical manifold, different features can be identified and dissimilarities computed, so that neighbourhoods of objects nearby a given example object can be constructed. This can reveal clustering and projections onto smaller eigen-subspaces which can make comparisons easier to interpret. Geodesic distances can be used as a natural dissimilarity metric applied over data described by probability distributions. Exploring this property, we propose a new face recognition method which scores dissimilarities between face images by multiplying geodesic distance approximations between 3-variate RGB Gaussians representative of colour face images, and also obtaining joint probabilities. The experimental results show that this new method is more successful in recognition rates than published comparative state-of-the-art methods.     

Topological constraint on scroll wave pinning

Scroll waves in an excitable medium rotate about tubelike filaments, whose ends, when they exist, can lie on the external boundary of the medium or be pinned to an inclusion. We derive a topological rule that governs such pinning. It implies that some configurations cannot occur although they might otherwise have been expected. Heart tissue provides an application of these concepts. Computational illustrations based on a FitzHugh-Nagumo model are given.     

基于白光数字莫尔的三维数字成像系统

提出一种基于数字莫尔的三维光学数字成像系统,此系统采用了非相干光投影和空间相移算法以及混合模板相位复原技术来重构连续位相分布图。给出一种光学几何灵敏度的确定方法并由此区得空间自由表面的三维数字图像。文中还给出由该光学数字化系统得以的真实人体面部的三维数字图像的实验结果。     

基于可调控多肽纳米管和石墨烯复合纳米结构的光吸收催化平台

近年来, 自组装纳米结构因为其容易制备、稳定、环保以及与各种功能基团、粒子等的多样结合能力吸引了科学家们的目光, 成为人们研究的热点课题, 在光电池、光催化、水凝胶、药物缓释等方面的实验科学领域得到了广泛的应用. 尤其是光催化方面, 自组装结构的重复性为激子的传递创造了比较良好的条件, 成为众多激子传递平台中的佼佼者. 本文报道了一种以苯丙氨酸二肽纳米管和羧基石墨烯为基础的自组装光吸收催化平台, 对其结构进行研究, 并使用该体系进行了烟酰胺腺嘌呤二核苷酸到它的还原态的催化实验. 该体系的微观结构由纳米管和石墨烯膜复合而成, 羧基石墨烯的存在能够降低纳米管直径, 实现纳米管的形态操控, 石墨烯与多肽纳米管复合纳米结构的存在实现了多通道协同激子传递, 降低了激子传递的距离, 极大增强了催化中心对于激子的接受和使用效率. 在复合了光敏剂和催化中心之后, 该体系具有较高的稳定性, 均一的分散性, 很强的光能吸收和转化能力等性质. 对于从NADP⁺往NADPH转变的催化实验表明, 该体系有较高的反应速率和催化效率, 并且比两种单一结构催化平台效果之和更好, 实现了一加一大于二的效应, 展现了复合纳米结构光吸收催化平台的巨大潜力和广阔应用前景.     

基于复合非线性数字滤波器的Hash函数构造

在对多个满足Kelber条件的滤波器组成的复合系统进行初步分析的基础上，提出了一个基于复合非线性数字滤波器的带密钥的Hash算法.算法首先构建能产生高维混沌序列的复合滤波器系统，然后在明文作用的复合序列控制下随机选择滤波器子系统，并以复合系统的初态作为密钥，以粗粒化的量化迭代轨迹作为明文的Hash值.讨论了复合系统实现Hash函数的不可逆性、防伪造性、初值敏感性等特点.研究结果表明：基于复合非线性数字滤波器的Hash算法简单快速，比基于单一混沌映射的Hash算法有着更高的安全性，同时滤波器结构中没有复杂的浮点运算，比一般复合混沌系统更易于软硬件实现. 关键词： Hash 函数 混沌 非线性自回归数字滤波器     

Determination of interface properties by spatial echo distribution processing

Echo amplitudes, detected by present ultrasonic pulse echo methods, are determined to a great part by the properties of the echo producing interfaces. Quantitative analysis by digital signal processing or sophisticated monitoring, especially by amplitude colour coding, appears to be advantageous only if these unwanted echo amplitude distortions can be avoided or compensated for.A promising way to achieve this aim may be the processing of the spatial echo distributions produced by reflection at the echo producing interfaces. In this paper it is shown by mathematical and experimental examination how interface properties can affect the spatial echo distributions.     

The acoustic telescope

A system has been developed for real-time sound source location on full-size jet engines. It consists of an array of microphones connected to a small digital computer, via a sequence of preamplifiers, analog filters and analog to digital converters and multiplexer. Microphone signals can be processed on-line to give displays of time varying source distributions or statistical averages with respect to position and frequency, by using a colour television as well as a display screen and printer/plotter. The whole system can be transported in a small estate car and can be used on both model scale and full size engine test rigs.A theoretical analysis of system performance is in terms of a line source of generally correlated omni-directional sound radiators, which shares the measurable far-field properties of a jet engine noise source. The general properties of the system are described, including its use to correlate spatially separated sound sources, application in the presence of ground reflections and use in a moving airstream. The statistical properties of apparent source distributions are also discussed.A series of experiments on a Rolls-Royce/SNECMA Olympus engine is described, in order to illustrate application of the system.     

近红外光谱技术在天然草地植被管理中的应用

植被是监测草地健康和生产力的主要依据,其变化是草地生态系统退化和恢复状况的最直接体现。及时掌握草地植被的变化信息是防止草地退化、实现草地生态系统可持续发展的首要条件。近红外光谱技术以其简便、快捷等优越性广泛应用于不同领域,在草地资源管理中有巨大的应用潜力和前景。文章介绍了近红外光谱技术的原理、特点及其在草地植被物种组成、草地植物茎叶比、凋落物及牧草品质测定等方面的应用特点,综合阐述了近红外光谱技术在草地植被管理中的应用现状,并对其应用前景进行了展望。     

New full-wave theory for scattering from rough metal surfaces—the correction current method: the TE-polarization case

A new full-wave theory of scattering from metal surfaces with one-dimensional roughness profiles is presented. A primary field and a complete system of modal functions (radiation modes) are defined to be relatively simple in structure (plane-wave-type fields) and to satisfy the boundary conditions at the rough surface, individually and rigorously. These fields will not necessarily satisfy Maxwell's equations. But compliance with these equations is enforced by the introduction of fictitious current distributions, associated with each of these fields, and chosen such that these 'passive' currents compensate for any field errors. In addition, each radiation mode is assumed to include an 'active' current distribution in the form of a current sheet which generates this mode. The composite field, formulated as a superposition of the primary field and the radiation modes, must be source free. It cannot involve any active or passive currents; and this zero-current requirement is then used to solve the scatter problem by an iterative procedure which, in a step-by-step fashion, eliminates the passive currents of the primary field and radiation modes by the active currents of the radiation modes. The result is a composite field that satisfies all requirements (Maxwell's equations, boundary conditions and radiation condition) while all fictitious current distributions are eliminated by mutual compensation. This composite field is therefore the solution of the scatter problem. This new theory—involving fictitious current distributions—is unconventional. But after definition of the primary field and the radiation modes, it is straightforward and conceptually transparent. The first-order scatter pattern is reciprocal and bridges the gap between the small-perturbation method and the physical optics method. Since the passive currents quantify the field errors, the theory allows the establishment of an error criterion which indicates when field errors can be expected to be small. The results are compared with those of existing theories. The present paper presents the TE case; the TM case, which is more complex, will be described in a follow-on paper.

(Some figures in this article are in colour only in the electronic version)     

Use of EDXRF elemental fingerprinting for discrimination of botanical and geographical origin of Slovenian bee pollen

Bee pollen contains proteins, amino acids, carbohydrates, fats, fatty acids, vitamins, polyphenols, and mineral nutrients that make it useful as a good nutritional supplement in the human diet. It has the richest elemental composition among bee products which is not uniform and consequently varies greatly depending on botanical and geographical origin. In polyfloral and selected monofloral bee pollen samples: sweet chestnut, maple, dandelion, rapeseed, flowering ash, buckwheat, common ivy, and plantain, the concentrations of P, S, Cl, K, Ca, Mn, Fe, Zn, Br, Rb, and Sr were determined. A non-destructive energy dispersive X-ray fluorescence spectrometry was used for elemental fingerprinting. The most abundant elements in Slovenian bee pollen are K, P, S, Ca, and Cl followed by Fe, Mn, Zn, Rb, Br, and Sr. Several statistically significant differences in the content of analysed elements were found between studied groups according to the botanical and geographical origin which can be related to soil and plant elemental composition and plant metabolism. The obtained data extend our previous chemical profiling of Slovenian bee pollen and contribute to a more precise evaluation of some essential mineral nutrients in bee pollen to cover recommended dietary allowances in human nutrition. Additionally, this work contributes to a better understanding of mineral nutrient requirements in honey bee nutrition and of the environmental and agricultural impact of this product.     

Data acquisition techniques in digital photoelasticity: a review

Advancements in the last two decades for data acquisition in digital photoelasticity have been brought out in this paper. Photoelasticity is an engineering tool and as an end user, one would like to know which of the techniques to be selected for a particular application. With this in view, the various techniques are reviewed and a brief summary of the steps involved in each of the techniques are also given. A need to capture the images in colour is indicated for full automation of data acquisition. Future directions of research in digital photoelasticity is also highlighted.     

Colour-stripe permutation pattern for rapid structured-light range imaging

For structured-light range imaging, colour stripes can be used for increasing the number of distinguishable light patterns compared to binary black-and-white stripes. Therefore, an appropriate use of colour patterns can reduce the number of required light projections for imaging an object scene, and range imaging can be achievable in a single video frame or in “one-shot”. On the other hand, the reliability and range resolution attainable from colour stripes are generally lower than those from temporally encoded binary black-and-white patterns since colour contrast is affected by object colour reflectance and ambient light. This paper presents new methods for selecting stripe colours and designing multiple-stripe patterns for “one-shot” and “two-shot” imaging. We show that maximizing colour contrast between the stripes in one-shot imaging reduces the ambiguities resulting from coloured object surfaces and limitations in sensor/projector resolution. Moreover, a cross-stripe gradient method is presented to improve estimation of illumination patterns in one-shot imaging. Two-shot imaging adds an extra video frame and maximizes the colour contrast between the first and second video frames to diminish the ambiguities even further. Experimental results and discussion demonstrate the effectiveness and robustness of the presented one-shot and two-shot colour-stripe imaging schemes.     

基于数字全息及离散余弦变换的图像数字水印技术

提出了一种以数字全息和离散余弦变换为基础的数字水印技术,实现了在原始图像中嵌入数字全息水印。考虑到数字全息图的不可撕毁性,使得数字全息水印本身就具有良好的抗剪切能力,并且与传统的二维灰度水印相比嵌入的信息更多。数字全息图通过傅里叶变换全息的方法获得,为了提高抗有损压缩能力,在数字全息水印嵌入过程中采用了基于(JPEG模型和分解离散余弦变换(DCT)系数的方法。实验表明,通过该算法获得的数字全息水印对JPEG有损压缩和剪切等图像处理操作均有很好的稳健性,并且采用密钥加强了水印的安全性。因此该算法能成为数字多媒体产品版权保护的有效方案。     

The colour of domestication and the designer chicken

Colour is an important feature of most living organisms. In the wild, colour has great significance affecting the survival and reproductive success of the species. The environmental constraints which lead to the specific colours of birds and animals are very strong and individuals of novel colours tend not to survive. Under domestication, mankind has transformed all the species involved which have thus been freed from environmental pressures to a large extent. Early colour variants were mostly selected for utility reasons or religious practices. In more recent centuries colour varieties have been created purely for ornament and pleasure, fashion playing a surprisingly large part in their development. A bewildering array of colours and patterns can now be found in all our commensal species, especially the Domestic Fowl (Gallus gallus domesticus).     

Telecommunication in a disordered environment with iterative time reversal

Abstract

We present a method to transmit digital information through a highly scattering medium in a MIMO-MU (multiple input multiple output multiple users) context. It is based on iterations of a time-reversal process, and permits us to focus short pulses, both spatially and temporally, from a base antenna to different users. This iterative technique is shown to be more efficient (lower inter-symbol interference and lower error rate) than classical time-reversal communication, while being computationally light and stable. Experiments are presented: digital information is conveyed from 15 transmitters to 15 receivers by ultrasonic waves propagating through a highly scattering slab. From a theoretical point of view, the iterative technique achieves the inverse filter of propagation in the subspace of non-null singular values of the time-reversal operator. We also investigate the influence of external additive noise, and show that the number of iterations can be optimized to give the lowest error rate.

(Some figures in this article are in colour only in the electronic version)