Kapazitätsoptimierung in paketvermittelten Datennetzen

Zusammenfassung In dieser Zeitschrift wurden bereitmehrfach Planungsprobleme in Nachrichten- und Datennetzen mit Methoden des Operations Research behandelt. Insbesondere das hier betrachtete Thema der Kapazitätsoptimierung in paketvermittelten Datennetzen wurde von Garcia [2] ausführlich dargestellt. Insofern stellt die vorliegende Arbeit eine Ergänzung zu jenem Artikel dar. Die Bestimmung kostenminimaler Kapazitäten in paketvermittelten Datennetzen läßt sich mathematisch als ganzzahliges nichtlineares Optimierungsproblem modellieren. Von Garcia wurden das zugehörige reelle Ersatzproblem gelöst und die Ergebnisse ganzzahlig aufgerundet, was zu nicht-optimalen Lösungen führen kann. Hier wird nun die diskrete Problemstruktur direkt benutzt und das Modell mittels drei Methoden (dynamischer Optimierung und zwei Heuristiken) gelöst. Diese drei Methoden liefern meist die gleichen Lösungen, wobei die Rechenzeiten der Heuristiken deutlich geringer als die der dynamischen Optimierung sind. Die hier enthaltenen Lösungen sind oft kostengünstiger als die in [2].

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Summary In this journal the treatment of planning problems in information and data networks by methods of Operations Research has already been treated several times. Especially the subject of capacity optimization discussed in this paper has already been extensively dealt with by Garcia [2]. Therefore this paper may be considered as a supplementary one. The specification of minimum cost capacities of packet switched data networks may be modelled as an integer nonlinear optimization problem. Garcia has solved the complementary real substitute problem with integer results, which may lead to non-optimal solutions. In this paper the model is based right on the discrete problem structure and solved by three different methods (dynamic programming and two heuristics). All three methods provide generally the same results, while computer time requirements of the heuristic methods are significantly below those of dynamic programming. Results will generally lead to cheaper solutions than by [2].

     

Laser-induced thermal acoustics (LITA) signals from finite beams

Laser-induced thermal acoustics (LITA) is a four-wave mixing technique that may be employed to measure sound speeds, transport properties, velocities, and susceptibilities of fluids. It is particularly effective in high-pressure gases (>1 bar). An analytical expression for LITA signals is derived by the use of linearized equations of hydrodynamics and light scattering. This analysis, which includes full finite-beam-size effects and the optoacoustic effects of thermalization and electrostriction, predicts the amplitude and the time history of narrow-band time-resolved LITA and broadband spectrally resolved (mulitplex) LITA signals. The time behavior of the detected LITA signal depends significantly on the detection solid angle, with implications for the measurement of diffusivities by the use of LITA and the proper physical picture of LITA scattering. This and other elements of the physics of LITA that emerge from the analysis are discussed. Theoretical signals are compared with experimental LITA data.     

Cosserat Rods with Projective Dynamics

We present a novel method to simulate Cosserat rods with Projective Dynamics (PD). The proposed method is both numerically robust and accurate with respect to the underlying physics, making it suitable for a variety of applications in computer graphics and related disciplines. Cosserat theory assigns an orientation frame to each point and is thus able to realistically simulate stretching and shearing effects, in addition to bending and twisting. Within the PD framework, it is possible to obtain accurate simulations given the implicit integration over time and its decoupling of the local‐global solve. In the proposed method, we start from the continuous formulation of the Cosserat theory and derive the constraints for the PD solver. We extend the standard definition of PD and add body orientations as system variables. Thus, we include the preservation of angular momentum, so that twisting and bending can be accurately simulated. Our formulation allows the simulation of different bending behaviors with respect to a user‐defined Young's modulus, the radius of the rod's cross‐section, and material density. We show how different material specifications in our simulations converge within a few iterations to a reference solution, generated with a high‐precision finite element method. Furthermore, we demonstrate mesh independence of our formulation: Refining the simulation mesh still results in the same characteristic motion, which is in contrast to previous position based methods.     

Nutzerdaten im Smart Grid — zur Notwendigkeit einer differenzierten grundrechtlichen Bewertung

Die Diskussion um die Auswirkungen des Einsatzes von Smart Metern auf die Pers?nlichkeitsrechte der Letztverbraucher hat — zu Recht — zun?chst das Grundrecht auf informationelle Selbstbestimmung in den Blick genommen. Die grundrechtlichen Probleme sind damit allerdings nicht ausgesch?pft: Da die Daten der h?uslichen Sph?re entstammen ist zu fragen, ob nicht auch der Schutzbereich von Art. 13 GG betroffen ist. Durch die Erhebung mittels eines IT-Systems (der Smart Meter) kann auch das Grundrecht auf Gew?hrleistung der Vertraulichkeit und Integrit?t informationstechnischer Systeme eingreifen. Schlie?lich stellt sich angesichts der Kommerzialisierung der Daten im Smart Grid die Frage, ob verm?genswerte Positionen betroffen sind.     

On the Substrate Binding of Linoleate 9-Lipoxygenases

Lipoxygenases (LOX; linoleate:oxygen oxidoreductase EC 1.13.11.12) consist of a class of enzymes that catalyze the regio- and stereo specific dioxygenation of polyunsaturated fatty acids. Here we characterize two proteins that belong to the less studied class of 9-LOXs, Solanum tuberosum StLOX1 and Arabidopsis thaliana AtLOX1. The proteins were recombinantly expressed in E. coli and the product specificity of the enzymes was tested against different fatty acid substrates. Both enzymes showed high specificity against all tested C18 fatty acids and produced (9S)-hydroperoxides. However, incubation of the C20 fatty acid arachidonic acid with AtLOX1 gave a mixture of racemic hydroperoxides. On the other hand, with StLOX1 we observed the formation of a mixture of products among which the (5S)-hydroperoxy eicosatetraenoic acid (5S-H(P)ETE) was the most abundant. Esterified fatty acids were no substrates. We used site directed mutagenesis to modify a conserved valine residue in the active site of StLOX1 and examine the importance of space within the active site, which has been shown to play a role in determining the positional specificity. The Val576Phe mutant still catalyzed the formation of (9S)-hydroperoxides with C18 fatty acids, while it exhibited altered specificity against arachidonic acid and produced mainly (11S)-H(P)ETE. These data confirm the model that in case of linoleate 9-LOX binding of the substrate takes place with the carboxyl-group first. Sequence data: The nucleotide sequences reported in this paper are annotated in the GenBank/EMBL data bank under the accession numbers Q06327 and S73865.     

Gestufte Kontrolle bei Videoüberwachungsanlagen

Moderne Videoüberwachungssysteme k?nnen über die übertragung und Aufnahme von Videobildern hinaus diese auch auswerten. Sie k?nnen dadurch zum einen die Gefahrenabwehr verbessern, sie greifen dadurch zum anderen aber auch tiefer in die Grundrechte der Betroffenen ein. Um hier zu einem neuen, angemessenen Ausgleich zwischen Sicherheit und Freiheit zu gelangen, wird für Gestaltung und Einsatz der modernen Videoüberwachungssysteme (1.) ein Drei-Stufen-Modell vorgestellt (2.). Dieses wird sodann verfassungs- und datenschutzrechtlich hergeleitet (3.) und in seiner Ausgestaltung rechtlich begründet (4.). Schlie?lich wird er?rtert, wie das Drei-Stufen-Modell im Rahmen von Erlaubnistatbest?nden zur Anwendung gebracht werden kann (5.).     

Matrix versus fracture permeability in a regional sandstone aquifer (Wajid sandstone,SW Saudi Arabia)

Sandstones are often characterized as fractured aquifers. We present a case study of the Wajid sandstone, which forms a regional aquifer system in SW Saudi Arabia, where matrix, fracture, and large-scale hydraulic conductivities are coincident. The measurements deal with different scales and methods and are based on porosity and permeability measurements in the laboratory, as well as pumping tests in the field. Porosities of the sandstone samples in general are high and range between less than 5?% and more than 45?%. Gas permeabilities for strongly cemented samples are <?1 mD, whereas most samples range in between 500 and 5,000 mD. There is only a weak anisotropy with preference of the horizontal x-, y-directions. Hydraulic conductivities of the matrix samples (5.5?·?10^?6 m/s and 1.1?·?10^?5 m/s for the Upper and Lower Wajid sandstone, respectively) were in the same order of magnitude compared to hydraulic conductivities derived from pumping tests (8.3?·?10^?5 m/s and 2.2?·?10^?5 m/s for the Upper and Lower Wajid sandstone, respectively).     

Sch?ffer, Heiko: Der Schutz des zivilen Luftverkehrs vor Terrorismus. Der Beitrag der International Civil Aviation Organization (ICAO), Nomos Universit?tsschriften Recht

Ohne Zusammenfassung