Digital watermarking robust to geometric distortions.

In this paper, we present two watermarking approaches that are robust to geometric distortions. The first approach is based on image normalization, in which both watermark embedding and extraction are carried out with respect to an image normalized to meet a set of predefined moment criteria. We propose a new normalization procedure, which is invariant to affine transform attacks. The resulting watermarking scheme is suitable for public watermarking applications, where the original image is not available for watermark extraction. The second approach is based on a watermark resynchronization scheme aimed to alleviate the effects of random bending attacks. In this scheme, a deformable mesh is used to correct the distortion caused by the attack. The watermark is then extracted from the corrected image. In contrast to the first scheme, the latter is suitable for private watermarking applications, where the original image is necessary for watermark detection. In both schemes, we employ a direct-sequence code division multiple access approach to embed a multibit watermark in the discrete cosine transform domain of the image. Numerical experiments demonstrate that the proposed watermarking schemes are robust to a wide range of geometric attacks.     

Aspectual Feature Modules

Two programming paradigms are gaining attention in the overlapping fields of software product lines (SPLs) and incremental software development (ISD). Feature-oriented programming (FOP) aims at large-scale compositional programming and feature modularity in SPLs using ISD. Aspect-oriented programming (AOP) focuses on the modularization of crosscutting concerns in complex software. Although feature modules, the main abstraction mechanisms of FOP, perform well in implementing large-scale software building blocks, they are incapable of modularizing certain kinds of crosscutting concerns. This weakness is exactly the strength of aspects, the main abstraction mechanisms of AOP. We contribute a systematic evaluation and comparison of FOP and AOP. It reveals that aspects and feature modules are complementary techniques. Consequently, we propose the symbiosis of FOP and AOP and aspectual feature modules (AFMs), a programming technique that integrates feature modules and aspects. We provide a set of tools that support implementing AFMs on top of Java and C++. We apply AFMs to a nontrivial case study demonstrating their practical applicability and to justify our design choices.     

An algebraic foundation for automatic feature-based program synthesis

Feature-Oriented Software Development provides a multitude of formalisms, methods, languages, and tools for building variable, customizable, and extensible software. Along different lines of research, different notions of a feature have been developed. Although these notions have similar goals, no common basis for evaluation, comparison, and integration exists. We present a feature algebra that captures the key ideas of feature orientation and that provides a common ground for current and future research in this field, on which also alternative options can be explored. Furthermore, our algebraic framework is meant to serve as a basis for the development of the technology of automatic feature-based program synthesis and architectural metaprogramming.     

The shape of feature code: an analysis of twenty C-preprocessor-based systems

Feature annotations (e.g., code fragments guarded by #ifdef C-preprocessor directives) control code extensions related to features. Feature annotations have long been said to be undesirable. When maintaining features that control many annotations, there is a high risk of ripple effects. Also, excessive use of feature annotations leads to code clutter, hinder program comprehension and harden maintenance. To prevent such problems, developers should monitor the use of feature annotations, for example, by setting acceptable thresholds. Interestingly, little is known about how to extract thresholds in practice, and which values are representative for feature-related metrics. To address this issue, we analyze the statistical distribution of three feature-related metrics collected from a corpus of 20 well-known and long-lived C-preprocessor-based systems from different domains. We consider three metrics: scattering degree of feature constants, tangling degree of feature expressions, and nesting depth of preprocessor annotations. Our findings show that feature scattering is highly skewed; in 14 systems (70 %), the scattering distributions match a power law, making averages and standard deviations unreliable limits. Regarding tangling and nesting, the values tend to follow a uniform distribution; although outliers exist, they have little impact on the mean, suggesting that central statistics measures are reliable thresholds for tangling and nesting. Following our findings, we then propose thresholds from our benchmark data, as a basis for further investigations.     

Access control in feature-oriented programming

In feature-oriented programming (FOP) a programmer decomposes a program in terms of features. Ideally, features are implemented modularly so that they can be developed in isolation. Access control mechanisms in the form of access or visibility modifiers are an important ingredient to attain feature modularity as they allow programmers to hide and expose internal details of a module’s implementation. But developers of contemporary feature-oriented languages have not considered access control mechanisms so far. The absence of a well-defined access control model for FOP breaks encapsulation of feature code and leads to unexpected program behaviors and inadvertent type errors. We raise awareness of this problem, propose three feature-oriented access modifiers, and present a corresponding access modifier model. We offer an implementation of the model on the basis of a fully-fledged feature-oriented compiler. Finally, by analyzing ten feature-oriented programs, we explore the potential of feature-oriented modifiers in FOP.     

A real-time vision module for interactive perceptual agents

Abstract. Interactive robotics demands real-time visual information about the environment. Real-time vision processing, however, places a heavy load on the robot's limited resources, which must accommodate multiple other processes running simultaneously. This paper describes a vision module capable of providing real-time information from ten or more operators while maintaining at least a 20-Hz frame rate and leaving sufficient processor time for a robot's other capabilities. The vision module uses a probabilistic scheduling algorithm to ensure both timely information flow and a fast frame capture. In addition, it tightly integrates the vision operators with control of a pan-tilt-zoom camera. The vision module makes its information available to other modules in the robot architecture through a shared memory structure. The information provided by the vision module includes the operator information along with a time stamp indicating information relevance. Because of this design, our robots are able to react in a timely manner to a wide variety of visual events.     

Diode-like ion-track asymmetric nanopores: Some alternative methods of fabrication

We present two fabrication methods which allow production of ion-track nanopore membranes with pronounced geometrical asymmetry and diode-like ionic conductivity. The asymmetry of the pores is provided by self-assembly of surfactant molecules at ion-track entrances on one side of the ion-irradiated polymer foil. On the other side of the membrane, the effect of surfactant is excluded using a pre-treatment with ultraviolet radiation or a surfactant-free etching solution. Highly tapered pore profiles are obtained and characterized using SEM and FESEM. In electrolyte solutions, the asymmetric pores thus fabricated exhibit a high rectification of electric current. The nanopores with a large angle aperture can be of interest for resistive-pulse technique applications and for the atomic beam projection nanolithography.     

Thermal Poling of Soda‐Lime Silica Glass with Nonblocking Electrodes—Part 1: Effects of Sodium Ion Migration and Water Ingress on Glass Surface Structure

It is generally well known that not only the sodium itself, but also the non‐bridging oxygen (NBO) sites associated with sodium ions are largely responsible for the surface reactivity of soda‐lime‐silica (SLS) glass. Thermal poling can modify the distribution of sodium in the subsurface region. In this work, a commercial SLS float glass was thermally poled using nonblocking electrodes in air. The Na⁺?depleted anode surface and the Na⁺?gradient cathode surface were characterized using a variety of methods to find the compositional, structural and morphological effects of thermal poling. Of particular significance is the use of nondestructive vibrational spectroscopy methods, which can lead to new and improved understanding of water interactions with sodium and its sites in the glass. It was found that during thermal poling, the Na⁺?depleted glass network on the anode side undergoes condensation reactions of NBO sites accompanied by the increase in concentrations of silanol (SiOH) groups and molecular water species. In contrast, silanol and water species do not increase and the silicate network change is negligible in the Na⁺?gradient cathode side. Vibrational sum frequency generation (SFG) spectroscopy analysis revealed the difference in distributions of hydrous species in the Na⁺?depleted and Na⁺?gradient surfaces. The structural information of the thermally‐poled surfaces provides critical insights needed to understand the mechanical and mechanochemical properties of the Na⁺?concentration modified SLS glass surfaces reported in the Part 2 companion paper.