260 research outputs found
Publishing H2O pluglets in UDDI registries
Interoperability and standards, such as Grid Services are a focus of current Grid research. The intent is to facilitate resource virtualization, and to accommodate the intrinsic heterogeneity of resources in distributed environments. It is important that new and emerging metacomputing frameworks conform to these standards, in order to ensure interoperability with other grid solutions. In particular, the H2O metacomputing system offers several benefits, including lightweight operation, user-configurability, and selectable security levels. Its applicability would be enhanced even further through support for grid services and OGSA compliance. Code deployed into the H2O execution containers is referred to as pluglets. These pluglets constitute the end points of services in H2O, services that are to be made known through publication in a registry. In this contribution, we discuss a system pluglet, referred to as OGSAPluglet, that scans H2O execution containers for available services and publishes them into one or more UDDI registries. We also discuss in detail the algorithms that manage the publication of the appropriate WSDL and GSDL documents for the registration process
Magnetic pulse welding
The contemporary construction industry is evolving with a rapid pace and is pushing technological boundaries. Together with that progress new requirements on joints and joining techniques are imposed. This paper describes our research concerning an advanced joining technique, the Magnetic Pulse Welding process (MPW).
The first part of this article briefly describes the MPW process and summarizes the differences with respect to conservative welding techniques. Secondly an analytical model of the process will be investigated on accuracy. This model was developed by the manufacturer of the MPW machine used at the Belgian Welding Institute. Further a description is given of the methods which are used to investigate the experimental joints. After describing the recently performed experiments, finally an overview will be given depicting the work that will be carried out during the rest of this master thesi
Numerical bifurcation analysis of pattern formation in a cell based auxin transport model
Transport models of growth hormones can be used to reproduce the hormone
accumulations that occur in plant organs. Mostly, these accumulation patterns
are calculated using time step methods, even though only the resulting steady
state patterns of the model are of interest. We examine the steady state
solutions of the hormone transport model of Smith et al (2006) for a
one-dimensional row of plant cells. We search for the steady state solutions as
a function of three of the model parameters by using numerical continuation
methods and bifurcation analysis. These methods are more adequate for solving
steady state problems than time step methods. We discuss a trivial solution
where the concentrations of hormones are equal in all cells and examine its
stability region. We identify two generic bifurcation scenarios through which
the trivial solution loses its stability. The trivial solution becomes either a
steady state pattern with regular spaced peaks or a pattern where the
concentration is periodic in time.Comment: submitte
Task-Set Generator for Schedulability Analysis using the TACLeBench benchmark suite
ABSTRACT Current real-time embedded systems evolve towards complex systems using new state of the art technologies such as multi-core processors and virtualization techniques. Both technologies requires new real-time scheduling algorithms. For uniprocessor scheduling, utilization-based evaluation methodologies are common and well-established. For multicore systems and virtualization, evaluating and comparing scheduling techniques using the tasks' parameters is more realistic. Evaluating these different scheduling techniques requires relevant and standardised task sets. Scheduling algorithms can be evaluated on three evaluation levels: 1) by using the mathematical model of the scheduling algorithm, 2) by simulating the scheduling algorithm and 3) by implementing the algorithm on the target platform. Generating task sets is straightforward in case of the first two levels; only the parameters of the tasks are required. Evaluating and comparing scheduling algorithms on the target platform itself, however, requires real executable tasks matching the predefined standardised task sets. Generating those executable tasks is not standardized yet. Therefore, we developed a task-set generator that generates reproducible, standardised task sets that are suitable at all levels. Beside generating the tasks' parameters, it includes an executable generator methodology that generates executables by combining publicly available benchmarks with know execution times. This paper presents and evaluates this task-set generator. The executables approximate the wanted execution time on the hardware platform
How grass keeps growing : an integrated analysis of hormonal crosstalk in the maize leaf growth zone
We studied the maize leaf to understand how long-distance signals, auxin and cytokinin, control leaf growth dynamics. We constructed a mathematical model describing the transport of these hormones along the leaf growth zone and their interaction with the local gibberellin (GA) metabolism in the control of cell division. Assuming gradually declining auxin and cytokinin supply at the leaf base, the model generated spatiotemporal hormone distribution and growth patterns that matched experimental data. At the cellular level, the model predicted a basal leaf growth as a result of cell division driven by auxin and cytokinin. Superimposed on this, GA synthesis regulated growth through the control of the size of the region of active cell division. The predicted hormone and cell length distributions closely matched experimental data. To correctly predict the leaf growth profiles and final organ size of lines with reduced or elevated GA production, the model required a signal proportional to the size of the emerged part of the leaf that inhibited the basal leaf growth driven by auxin and cytokinin. Excision and shading of the emerged part of the growing leaf allowed us to demonstrate that this signal exists and depends on the perception of light intensity
Applying numerical continuation to the parameter dependence of solutions of the Schr\"odinger equation
In molecular reactions at the microscopic level the appearance of resonances
has an important influence on the reactivity. It is important to predict when a
bound state transitions into a resonance and how these transitions depend on
various system parameters such as internuclear distances. The dynamics of such
systems are described by the time-independent Schr\"odinger equation and the
resonances are modeled by poles of the S-matrix. Using numerical continuation
methods and bifurcation theory, techniques which find their roots in the study
of dynamical systems, we are able to develop efficient and robust methods to
study the transitions of bound states into resonances. By applying Keller's
Pseudo-Arclength continuation, we can minimize the numerical complexity of our
algorithm. As continuation methods generally assume smooth and well-behaving
functions and the S-matrix is neither, special care has been taken to ensure
accurate results. We have successfully applied our approach in a number of
model problems involving the radial Schr\"odinger equation
Numerical Continuation of Bound and Resonant States of the Two Channel Schr\"odinger Equation
Resonant solutions of the quantum Schr\"odinger equation occur at complex
energies where the S-matrix becomes singular. Knowledge of such resonances is
important in the study of the underlying physical system. Often the
Schr\"odinger equation is dependent on some parameter and one is interested in
following the path of the resonances in the complex energy plane as the
parameter changes. This is particularly true in coupled channel systems where
the resonant behavior is highly dependent on the strength of the channel
coupling, the energy separation of the channels and other factors. In previous
work it was shown that numerical continuation, a technique familiar in the
study of dynamical systems, can be brought to bear on the problem of following
the resonance path in one dimensional problems and multi-channel problems
without energy separation between the channels. A regularization can be defined
that eliminates coalescing poles and zeros that appear in the S-matrix at the
origin due to symmetries. Following the zeros of this regularized function then
traces the resonance path. In this work we show that this approach can be
extended to channels with energy separation, albeit limited to two channels.
The issue here is that the energy separation introduces branch cuts in the
complex energy domain that need to be eliminated with a so-called
uniformization. We demonstrate that the resulting approach is suitable for
investigating resonances in two-channel systems and provide an extensive
example
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