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In 2000 the iSign project started as a virtual web-based laboratory for students of study program electrical engineering. Continuous development in the last years led to a heterogeneous learning environment offering learning material, adaptive user settings and access to a simulation tool. Access is available via web and wireless devices such as PCs, Laptops, PDAs, smartphones and mobile phones. Our attempt to adapt the content to the user's needs and the currently used device led us to a XML based data structure. This report shows our research results about content adaptation based on XML data. The two main aspects for that process are: the device capabilities and the adaptation methods using XML data.
In short-reach connections, large-diameter multimode fibres allow for robust and easy connections. Unfortunately, their propagation properties depend on the excitation conditions. We propose a launching technique using a fibre stub that can tolerate fabrication tolerances in terms of tilts and off-sets to a large extent. A study of the influence of displaced connectors along the transmission link shows that the power distributions approach a steady-state power distribution very similar to the initial distribution established by the proposed launching scheme.
The University for Children is a very successful event aiming to spark children‧s interest in science, in this particular lecture in Optics and Photonics. It is from brain research that we know about the significant dependence of successful learning on the fun factor. Researchers in this field have shown that knowledge acquired with fun is stored for a longer time in the long-term memory and can be used both more efficiently and more creatively [1], [2]. Such an opportunity to inspire the young generation for science must not be wasted. The world of Photonics and Optics provides us with a nearly inexhaustible source of opportunities of this kind.
Mobile learning (m-learning) can be considered as a new paradigm of e-learning. The developed solution enables the presentation of animations and 3D virtual reality (VR) on mobile devices and is well suited for mobile learning. Difficult relations in physics as well as intricate experiments in optics can be visualised on mobile devices without need for a personal computer. By outsourcing the computational power to a server, the coverage is worldwide.
In the year 2009 several data privacy scandals have hit the headlines where major corporations had a legitimate need for detecting fraud conducted by their own employees, but chose inappropriate measures for data screening. This contribution presents architectures and pseudonymization technology for privacy compliant fraud screening or fraud detection, in order to reduce the number of undiscovered fraud cases and to reduce the time to discovery.
In recent years, light-weight cryptography has received a lot of attention. Many primitives suitable for resource-restricted hardware platforms have been proposed. In this paper, we present a cryptanalysis of the new stream cipher A2U2 presented at IEEE RFID 2011 [9] that has a key length of 56 bit. We start by disproving and then repairing an extremely efficient attack presented by Chai et al. [8], showing that A2U2 can be broken in less than a second in the chosen-plaintext case. We then turn our attention to the more challenging known-plaintext case and propose a number of attacks. A guess-and-determine approach combined with algebraic cryptanalysis yields an attack that requires about 249 internal guesses. We also show how to determine the 5-bit counter key and how to reconstruct the 56-bit key in about 238 steps if the attacker can freely choose the IV. Furthermore, we investigate the possibility of exploiting the knowledge of a “noisy keystream” by solving a Max-PoSSo problem. We conclude that the cipher needs to be repaired and point out a number of simple measures that would prevent the above attacks.
The paper focuses on a numerical model which describes the radial temperature evolution in an optical fiber during the heating and cooling process according to the SP1 approximation. Based on this model, experimental methods for temperature measurement with optical fibers and for splice process optimization can be developed.
In the brain-cell microenvironment, diffusion plays an important role: apart from delivering glucose and oxygen from the vascular system to brain cells, it also moves informational substances between cells. The brain is an extremely complex structure of interwoven, intercommunicating cells, but recent theoretical and experimental works showed that the classical laws of diffusion, cast in the framework of porous media theory, can deliver an accurate quantitative description of the way molecules are transported through this tissue. The mathematical modeling and the numerical simulations are successfully applied in the investigation of diffusion processes in tissues, replacing the costly laboratory investigations. Nevertheless, modeling must rely on highly accurate information regarding the main parameters (tortuosity, volume fraction) which characterize the tissue, obtained by structural and functional imaging. The usual techniques to measure the diffusion mechanism in brain tissue are the radiotracer method, the real time iontophoretic method and integrative optical imaging using fluorescence microscopy. A promising technique for obtaining the values for characteristic parameters of the transport equation is the direct optical investigation using optical fibers. The analysis of these parameters also reveals how the local geometry of the brain changes with time or under pathological conditions. This paper presents a set of computations concerning the mass transport inside the brain tissue, for different types of cells. By measuring the time evolution of the concentration profile of an injected substance and using suitable fitting procedures, the main parameters characterizing the tissue can be determined. This type of analysis could be an important tool in understanding the functional mechanisms of effective drug delivery in complex structures such as the brain tissue. It also offers possibilities to realize optical imaging methods for in vitro and in vivo measurements using optical fibers. The model also may help in radiotracer biomarker models for the understanding of the mechanism of action of new chemical entities.