Shape ellipticity based on the first Hu moment invariant

In this paper we use the first Hu moment invariant to define a new ellipticity measure. The new ellipticity measure ranges over the interval $(0,1]$ and picks the value 1 if and only if the measured shape is an ellipse. The measure is invariant with respect to translation, rotation and scaling transformations. It is straightforward and fast to compute.     

A novel active disturbance rejection based tracking design for laser system with quadrant photodetector

A new tracking design for laser systems with different arrangements of a quadrant photodetector, based on the principle of active disturbance rejection control is suggested. The detailed models of quadrant photodetector with standard add–subtract, difference-over-sum and diagonal-difference-over-sum algorithms for displacement signals are included in the control loop. Target moving, non-linearity of a photodetector, parameter perturbations and exterior disturbances are treated as a total disturbance. Active disturbance rejection controllers with linear extended state observers for total disturbance estimation and rejection are designed. Proposed methods are analysed in frequency domain to quantify their stability characteristics and disturbance rejection performances. It is shown through simulations, that tracking errors are effectively compensated, providing the laser spot positioning in the area near the centre of quadrant photodetector where the mentioned algorithms have the highest sensitivity, which provides tracking of the manoeuvring targets with high accuracy.     

Efficient method for lossless LIDAR data compression

Light Detection and Ranging (LIDAR) has become one of the prime technologies for rapid collection of vast spatial data, usually stored in a LAS file format (LIDAR data exchange format standard). In this article, a new method for lossless LIDAR LAS file compression is presented. The method applies three consequent steps: a predictive coding, a variable-length coding and an arithmetic coding. The key to the method is the prediction schema, where four different predictors are used: three predictors for x, y and z coordinates and a predictor for scalar values, associated with each LIDAR point. The method has been compared with the popular general-purpose methods and with a method developed specially for compressing LAS files. The proposed method turns out to be the most efficient in all test cases. On average, the LAS file is losslessly compressed to 12% of its original size.     

Understanding the new digital divide—A typology of Internet users in Europe

The purpose of this study is to better understand the digital divide by identifying the variety of ways in which people in Europe use the Internet. First, by using cluster analysis on survey data (N=12,666/age: 16–74 years) from Eurostat on Internet usage in Norway, Sweden, Austria, the UK, and Spain, we identified five user types: Non-Users (42%), Sporadic Users (18%), Instrumental Users (18%), Entertainment Users (10%), and Advanced Users (12%). These user types differ in their distributions over country, age, access, household members, and gender. An alarming finding is that 60% of the population was found to be either Non-Users or Sporadic Users, which reflects a large digital divide in Europe. Second, we conducted a logistic regression to identify the predictors for different user types. We found on a cross-national level that age and Internet access are the most salient predictors, whereas gender and household seems to be less relevant. However, the amount of variance explained differs between countries. We also suggested a future increase in the digital divide between the identified user types—a user type divide. The user typology and the identified predictors might help researchers, practitioners, and decision makers to better understand Internet users and the multi-complex variations among individuals and countries. This knowledge will also serve as a means to understand the digital divide by providing a more nuanced perspective on Europeans' unequal usage of the Internet and participation in an increasingly digital society.     

Multimodal behavior realization for embodied conversational agents

Applications with intelligent conversational virtual humans, called Embodied Conversational Agents (ECAs), seek to bring human-like abilities into machines and establish natural human-computer interaction. In this paper we discuss realization of ECA multimodal behaviors which include speech and nonverbal behaviors. We devise RealActor, an open-source, multi-platform animation system for real-time multimodal behavior realization for ECAs. The system employs a novel solution for synchronizing gestures and speech using neural networks. It also employs an adaptive face animation model based on Facial Action Coding System (FACS) to synthesize face expressions. Our aim is to provide a generic animation system which can help researchers create believable and expressive ECAs.     

Proof rules for gotos

Summary We offer a program specification format adapted to statements with multiple exits, and use it to present proof rules to replace the somewhat unsatisfactory treatment of jumps in [3]. We justify the bridled use of gotos in return exits, failure exits, and loops with jumps in the middle. To exemplify our methodology, we prove the function Lookup.     

X-ray diffraction and Fourier transform-infrared analysis of the rust formed by corrosion of steel in aqueous solutions

Chemical and structural properties of the rust formed by corrosion of steel in aqueous solutions were studied by X-ray diffraction and Fourier transform infrared (FT-IR) spectroscopy. The corrosion products of steel were generated in aqueous solutions of different electrolyte compositions at room temperature (20 °C) or in an autoclave at 120 °C. X-ray diffraction analysis showed the presence of different oxide phases in the rust, such as lepidocrocite, magnetite, ferrihydrite, goethite and haematite. In all samples, the presence of an amorphous fraction was detected. Ferrihydrite was detected only in the rust samples formed at 120 °C, The characteristic properties of the FT-IR spectrum of the ferrihydrite component in the rust were investigated. Phase compositions of the corrosion products depended on the formation temperature and the electrolyte composition of the aqueous solutions. The influence of chloride, nitrate or sulphate anions on the phase composition of the rust is discussed.     

Computationally efficient application of the generic shape-illumination invariant to face recognition from video

As a problem of high practical appeal but many outstanding challenges, computer-based face recognition remains a topic of extensive research attention. In this paper we are specifically interested in the task of identifying a person using multiple images both in training and as a query. Thus, a novel method is proposed which advances the state-of-the-art in set-based face recognition. The introduced approach is based on a previously described invariant in the form of generic shape-illumination effects. The contributions include (i) an analysis of the computational demands of the original method and a demonstration of its practical limitations, (ii) a novel representation of personal appearance in the form of linked mixture models in image and pose-signature spaces, and (iii) an efficient (in terms of storage needs and matching time) manifold re-illumination algorithm based on the aforementioned representation. An evaluation and comparison of the proposed method with the original generic shape-illumination algorithm shows that comparably high recognition rates are achieved on a large data set (1.5% error on 700 face sets containing 100 individuals and extreme illumination variation) with a dramatic improvement in matching speed (over 700 times for sets containing 1600 faces) and storage requirements (independent of the number of training images). Theoretical and empirical findings of the present work are used to identify and discuss avenues for future research.