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In this paper an ultra-low power VCSEL with an electrical consumption of below 5 mW is characterised to electrical power, optical power, temperature as well as a spectral investigation. First the pigtail manufacture is described, where amongst others the VCSEL is bonded on a ceramic carrier and connected to an optical fibre by front surface coupling. Thereby the fibre-chip coupling is realised by...
We consider some possible broad changes that may impact society as a whole as a result of widespread integration of full-spectrum deployed pervasive computing technologies. Our approach considers design challenges for successfully developing and integrating pervasive technologies into culture and society. This is particularly challenging, since pervasive technologies as services are most successful...
Simulation is a fundamental means for evaluating mobile applications based on ad-hoc networks. This has led to the design of a large number of mobility models for simulating realistic user movement under physical constraints (obstacles, acceleration, inertia etc.). In recent years, the new breed of social mobility models (SMMs) has risen. These SMMs model the social aspects of human mobility, i.e...
A new reactive collision avoidance approach for mobile robots moving in cluttered and complex environments was developed and implemented. The novelty of this approach lies in the creation of a new method for analyzing openings in front of the robot that highly reduces their number when compared with the Nearness-Diagram Navigation (ND) technique, particularly in complex scenarios. Moreover, the angular...
The paper presents first findings of a study in wireless LAN security (WLAN) in German companies and federal authorities. The study was conducted in spring 2009. We formulate hypotheses derived from several studies in WLAN security. We analyze how the situation in Germany fits these assumptions. Degree of familiarity, frequency of use and reasons for not using wireless LAN security measures are being...
The smart grid of the future, while expected to affect all areas of the electric power system, from generation, to transmission, to distribution, cannot function without an extensive data communication system. Smart grid has the potential to support high levels of distributed generation (DG); however the current standards governing the interconnection of DG do not allow the implementation of several...
To predict the three dimensional structure of proteins, many computational methods sample the conformational space, generating a large number of candidate structures. Subsequently, such methods rank the generated structures using a variety of model quality assessment programs in order to obtain a small set of structures that are most likely to resemble the unknown experimentally determined structure...
From a mobile networking perspective, spacecraft networks are characterized by the predictability of node movement and communication opportunities. We show that payload data throughput, spacecraft commanding, and mission autonomy can be enhanced by using a predicable mobile routing protocol. We validate our claims through realistic network simulations in the context of a complex communication infrastructure...
The diffusion behavior of different solvents and repair chemicals in a porous SiCOH with pores of ~ 1,5 nm was studied. It was found for molecule with a size les 1/3 of the pore size the diffusion coefficient (De) depends mainly on the size of the molecule, while a size Gt 1/3 of the pore size does not show a linear dependency of De on the molecules size. In this regime De is mainly a function of...
Photonic crystal fibers have opened interesting new ways for guiding ultrashort laser pulses. Hollow-core fibers (HCF) enable guiding of short light pulses at significantly reduced nonlinearities, which avoids nonlinear distortions to the extent possible. The latest generation of these fibers exhibits remarkably low losses, which suggests HCFs as the ideal choice for femtosecond beam delivery. However,...
We demonstrate a novel photonic-crystal fiber architecture that breaks with the paradigm of lattice homogeneity and enables a new degree of freedom in photonic-crystal-fiber design. We experimentally demonstrate guiding of ap20-fs pulses over meter distance.
Predictable mobile networks are dynamic in terms of the mobility and connectivity of the network nodes. However, in contrast to mobile ad-hoc networks, their dynamics are mostly predictable, as the name suggests. Currently, no adequate topology model exists for such networks. Moreover, routing protocols based on either static or mobile ad-hoc topology models do not exploit this predictability and...
In recent times, the importance of information security in civilian space communication systems has increased significantly among space agencies. Those systems often require a high degree of flexibility, interoperability and scalability. Therefore the usage of traditional, physical layer based security solutions is not a desirable option for the agencies. In this paper, we investigate the application...
This paper introduces a block oriented lossless compression method for magnetic field data produced by a 2-channel 3-axes fluxgate magnetometer. The presented method is based on a combination of differential, Golomb-Rice and truncated Huffman coding. Several previous approaches are examined and evaluated for their adequacy to be used in a low memory and computation power environment, such as the magnetometer...
Digital libraries are keystones for satisfying a specialized information demand. One big challenge for a successful digital library project is the consideration of the economic issues. We introduce an approach for the development of a revenue model. A case study for the DMG-Lib project is presented to show the practicability of our approach.
The development of clinical applications of magnetocardiography has been impeded by the large size of the systems used to measure magnetic fields. Here we present the first measurements of the cardiac electromagnetic field with a highly miniaturized (20 mm3), atomic magnetometer constructed by microfabrication techniques. Measurements were performed in two mice. The magnetometer was placed close to...
The impact of digital libraries on information processes is steadily growing. Today, a rapidly increasing number of digital libraries with various characteristics are available. Business models for digital libraries evolve from mere content providers to sophisticated service suppliers. They offer a rich variety of information services combined with collaboration, e-learning and portal features. Traditional...
Overcurrents on distribution systems include permanent faults, temporary faults and other lower magnitude surges, typically from switching events. The overcurrent environment of the distribution system requires quantification if improvements are to be made in power quality, protection and reliability. New and more complex overcurrent protection products require more exact knowledge of feeder conditions...
Using an anomalously dispersive microstructure fiber and two different saturable absorber mirrors at 1.06 mum, we demonstrate soliton-like 180-fs pulses in addition to 400-fs pulses with up to 0.1 nJ energy using only intra-fiber dispersion compensation.
We demonstrate a MFL with a single 5-air-hole annulus yielding a 280-mW output power at 52% slope efficiency. This high efficiency is attributed to a novel doping process and a special design of the MFL
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