Nonlinear Supersymmetric Quantum Mechanics: concepts and realizations

Nonlinear SUSY approach to preparation of quantum systems with pre-planned spectral properties is reviewed. Possible multidimensional extensions of Nonlinear SUSY are described. The full classification of ladder-reducible and irreducible chains of SUSY algebras in one-dimensional QM is given. Emergence of hidden symmetries and spectrum generating algebras is elucidated in the context of Nonlinear SUSY in one- and two-dimensional QM.Comment: 75 pages, Minor corrections, Version published in Journal of Physics

Architecture of a Large-scale Location Service

Many mobile applications require some knowledge about the current geographic locations of the mobile objects involved. Therefore, services exist that can store and retrieve the position of mobile objects in an efficient and scalable way. More advanced location-aware applications, however, require additional functionality, like determining all mobile objects inside a certain geographic area (range query). This functionality is not supported by existing services on a large scale yet. In this paper, we present a generic large-scale location service. We describe the location service model, defining the semantics of position, range and nearest neighbor queries. A hierarchical distributed architecture is presented, which can efficiently process these queries, and the structure of a main-memory database for efficiently storing and retrieving position information on a location server. Finally, through measurements on a first prototype of this architecture, we show the feasibility of such a location service

A Map-based Dead-reckoning Protocol for Updating Location Information

An important aspect of location-aware services is the management of location information. To this end, location information needs to be transferred from a mobile device, which determines this information by means of a local positioning sensor (such as GPS), to a location service, where the location information can be queried by applications. Because bandwidth in wide area mobile communications is still scarce and expensive, it is important to use an update protocol that requires as few messages as possible while still guaranteeing a desired accuracy of the location information. To decrease the number of necessary update messages, so-called dead-reckoning strategies have been proposed. In this paper we give an overview of different variants of dead-reckoning protocols for updating location information and propose a new map-based protocol. While a simple dead-reckoning protocol already reduces the number of update messages by up to 83%, the map-based protocol further reduces their number by again up to 60%

Analysis of Distribution Schemes for the Management of Location Information

New applications in the area of mobile computing make heavy use of knowledge about the applica-tion’s run-time environment. Applications running on mobile devices in particular exploit knowl-edge about their current geographical position or query for the location of other interesting objects. To manage such queries some applications provide a location service specifically tailored for their needs. The efficient and application-independent handling of such queries calls for a global and uni-versal location service. Considering a large number of users and queries to be handled, a distributed implementation of a location service is necessary. This paper analyses three schemes for the parti-tioning of location information and derives a performance model for these partitioning schemes. Fi-nally, an example for the application of the analysis ’ results is presented for a universal location serv-ice within the Nexus system, an infrastructure for location aware mobile computing.

Analysis of Distribution Schemes for the Management of Location Information

New applications in the area of mobile computing make heavy use of knowledge about the application 's run-time environment. Applications running on mobile devices in particular exploit knowledge about their current geographical position or query for the location of other interesting objects. To manage such queries some applications provide a location service specifically tailored for their needs. The efficient and application-independent handling of such queries calls for a global and universal location service. Considering a large number of users and queries to be handled, a distributed implementation of a location service is necessary. This paper analyses three schemes for the partitioning of location information and derives a performance model for these partitioning schemes. Finally, an example for the application of the analysis' results is presented for a universal location service within the Nexus system, an infrastructure for location aware mobile computing. 2 1 Intro..