900 research outputs found
Wireless internet architecture and testbed for wineglass
One of the most challenging issues in the area of mobile communication is the deployment of IPbased
wireless multimedia networks in public and business environments. The public branch may involve public
mobile networks, like UMTS as 3G system, while the business branch introduces local radio access networks by
means of W-LANs. Conventional mobile networks realise mobile specific functionality, e.g. mobility management
or authentication and accounting, by implementing appropriate mechanisms in specific switching nodes (e.g.
SGSN in GPRS). In order to exploit the full potential of IP networking solutions a replacement of these
mechanisms by IP-based solutions might be appropriate. In addition current and innovative future services in
mobile environments require at least soft-guaranteed, differentiated QoS. Therefore the WINE GLASS project
investigates and implements enhanced IP-based techniques supporting mobility and QoS in a wireless Internet
architecture. As a means to verify the applicability of the implemented solutions, location-aware services
deploying both IP-mobility and QoS mechanisms will be implemented and demonstratedPeer ReviewedPostprint (published version
Using Lyman- transits to constrain models of atmospheric escape
Lyman- transits provide an opportunity to test models of atmospheric
escape directly. However, translating observations into constraints on the
properties of the escaping atmosphere is challenging. The major reason for this
is that the observable parts of the outflow often comes from material outside
the planet's Hill sphere, where the interaction between the planetary outflow
and circumstellar environment is important. As a result, 3D models are required
to match observations. Whilst 3D hydrodynamic simulations are able to match
observational features qualitatively, they are too computationally expensive to
perform a statistical retrieval of properties of the outflow. Here, we develop
a model that determines the trajectory, ionization state and 3D geometry of the
outflow as a function of its properties and system parameters. We then couple
this model to a ray tracing routine in order to produce synthetic transits. We
demonstrate the validity of this approach, reproducing the trajectory of the
outflows seen in 3D simulations. We illustrate the use of this model by
performing a retrieval on the transit spectrum of GJ 436 b. Our model
constrains the sound speed of the outflow ,
indicating that we can rule out core-powered mass loss as the mechanism driving
the outflow for this planet. The bound on planetary outflow velocity and mass
loss rates are consistent with a photoevaporative wind
Variability of young stars: Determination of rotational periods of weak-line T Tauri stars in the Cepheus-Cassiopeia star-forming region
We report on observation and determination of rotational periods of ten
weak-line T Tauri stars in the Cepheus-Cassiopeia star-forming region.
Observations were carried out with the Cassegrain-Teleskop-Kamera (CTK) at
University Observatory Jena between 2007 June and 2008 May. The periods
obtained range between 0.49 d and 5.7 d, typical for weak-line and post T Tauri
stars.Comment: 11 pages, 26 figures, accepted to be published in A
Syzygies of torsion bundles and the geometry of the level l modular variety over M_g
We formulate, and in some cases prove, three statements concerning the purity
or, more generally the naturality of the resolution of various rings one can
attach to a generic curve of genus g and a torsion point of order l in its
Jacobian. These statements can be viewed an analogues of Green's Conjecture and
we verify them computationally for bounded genus. We then compute the
cohomology class of the corresponding non-vanishing locus in the moduli space
R_{g,l} of twisted level l curves of genus g and use this to derive results
about the birational geometry of R_{g, l}. For instance, we prove that R_{g,3}
is a variety of general type when g>11 and the Kodaira dimension of R_{11,3} is
greater than or equal to 19. In the last section we explain probabilistically
the unexpected failure of the Prym-Green conjecture in genus 8 and level 2.Comment: 35 pages, appeared in Invent Math. We correct an inaccuracy in the
statement of Prop 2.
Prerequisites for setting up management system in municipal retail trade
The relevance of the problem is determined by the number of complex problems that exist in present Samara municipal retail trade system, which is manifested in the lack of regulation, a glut of sales area, poorly developed infrastructure. The purpose of this article is to form a quantitative base for determining the municipal needs in the floor space. Leading method to study this problem is the method of empirical observations and mathematical modeling. The study results: the article contains the analysis of sales area availability on the example in the urban district and presents a quantitative method to determine predictive values for retail trade turnover. Practical significance: the paper is aimed to develop managerial decisions in the sphere of municipal trade regulation. © 2016 Suraeva et al
Geometric invariant theory of syzygies, with applications to moduli spaces
We define syzygy points of projective schemes, and introduce a program of
studying their GIT stability. Then we describe two cases where we have managed
to make some progress in this program, that of polarized K3 surfaces of odd
genus, and of genus six canonical curves. Applications of our results include
effectivity statements for divisor classes on the moduli space of odd genus K3
surfaces, and a new construction in the Hassett-Keel program for the moduli
space of genus six curves.Comment: v1: 23 pages, submitted to the Proceedings of the Abel Symposium
2017, v2: final version, corrects a sign error and resulting divisor class
calculations on the moduli space of K3 surfaces in Section 5, other minor
changes, In: Christophersen J., Ranestad K. (eds) Geometry of Moduli.
Abelsymposium 2017. Abel Symposia, vol 14. Springer, Cha
Three embeddings of the Klein simple group into the Cremona group of rank three
We study the action of the Klein simple group G consisting of 168 elements on
two rational threefolds: the three-dimensional projective space and a smooth
Fano threefold X of anticanonical degree 22 and index 1. We show that the
Cremona group of rank three has at least three non-conjugate subgroups
isomorphic to G. As a by-product, we prove that X admits a Kahler-Einstein
metric, and we construct a smooth polarized K3 surface of degree 22 with an
action of the group G.Comment: 43 page
Complete determination of the reflection coefficient in neutron specular reflection by absorptive non-magnetic media
An experimental method is proposed which allows the complete determination of
the complex reflection coefficient for absorptive media for positive and
negative values of the momenta. It makes use of magnetic reference layers and
is a modification of a recently proposed technique for phase determination
based on polarization measurements. The complex reflection coefficient
resulting from a simulated application of the method is used for a
reconstruction of the scattering density profiles of absorptive non-magnetic
media by inversion.Comment: 14 pages, 4 figures, reformulation of abstract, ref.12 added,
typographical correction
Evaluating inputs for organic farming – a new system. Proposals of the ORGANIC INPUTS EVALUATION project
This volume contains proposals for criteria for evaluation of plant protection products, fertilisers and soil conditioners1 to be used in organic agriculture. These ideas were developed in the course of the European Union (EU) Concerted Action project ‘ORGANIC INPUTS EVALUATION’ (QLK5-CT-2002-02565). For more information on this project see the end of this volume or visit the project website www.organicinputs.org. The documents in this volume are proposals elaborated by the project consortium and external experts. They were discussed with a broader audience at a public conference held in Brussels on October 13, 2005, and have been amended accordingly.
Our proposals also include a “criteria matrix”, which is in Microsoft Excel format, and therefore stands as a separate file. The criteria matrix is discussed in section 5, but we strongly recommend that you consult the original document. To illustrate the use of the matrix, we have further prepared two case studies, which are also separate Excel files. All of these files are contained on the CD, and can also be downloaded from the project website.
Currently, Regulation 2092/91 is under revision. We hope that our ideas can be incorporated into the regulation during this revision! In addition, we strongly encourage national institutions to make use of our proposals at the national level
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