Quantitative MR Imaging of the Electric Properties and Local SAR based on Improved RF Transmit Field Mapping

This work presents three new quantitative methods for magnetic resonance imaging. A method for simultaneous mapping of B1 and T1 (MTM) is developed and validated. Electric Properties Tomography (EPT), a method for quantitative imaging of dielectric properties of tissue, is presented. Based on EPT, separate (phase-based) conductivity and (amplitude-based) permittivity measurements are introduced. Finally, a B1-based method for patient-specific local SAR measurements is presented

Quantitative MR Imaging of the Electric Properties and Local SAR based on Improved RF Transmit Field Mapping

This work presents three new quantitative methods for magnetic resonance imaging. A method for simultaneous mapping of B1 and T1 (MTM) is developed and validated. Electric Properties Tomography (EPT), a method for quantitative imaging of dielectric properties of tissue, is presented. Based on EPT, separate (phase-based) conductivity and (amplitude-based) permittivity measurements are introduced. Finally, a B1-based method for patient-specific local SAR measurements is presented

Dynamic buy-back for product recovery in end-of-life spare parts procurement

The efficient supply of spare parts is of prime concern for OEMs. Next to the traditional spare parts sources in form of final order and remanufacturing, the option to buy back broken products prevents the OEM from fulfilling his spare parts availability obligation in the end-of-life phase and increases his ability to remanufacture. This contribution seeks to identify optimal buy-back strategies for different settings regarding information availability and buy-back flexibility. A numerical study analyzes circumstances under which buy-back is especially beneficial for the OEM.Inventory Management, Spare Parts Management, Reverse Logistics, Buy-back

Dynamic buy-back for product recovery in end-of-life spare parts procurement

The efficient supply of spare parts is of prime concern for OEMs. Next to the traditional spare parts sources in form of final order and remanufacturing, the option to buy back broken products prevents the OEM from fulfilling his spare parts availability obligation in the end-of-life phase and increases his ability to remanufacture. This contribution seeks to identify optimal buy-back strategies for different settings regarding information availability and buy-back flexibility. A numerical study analyzes circumstances under which buy-back is especially beneficial for the OEM

Evaluating Groupware for Creative Group Processes – The Case Study of CreativeFlow

The creative potential of teams plays a crucial role in generating the competitive advantage of organizations. We introduce an architecture supporting creative group processes in the context of business processes. Based on the theoretical concept of Pockets of Creativity (Seidel et al. 2010), the architecture aims to balance freedom for creative group work and constraints set by the processes in its environment. The architecture is implemented in the prototype CreativeFlow, integrating a groupware component and a workflow component. The prototype is evaluated in a case study in a TV production company. Free participation in group tasks and support for the structuring of ideas were deemed appropriate for the support of creative group processes. Process structure is mainly imposed by project deadlines that require user notification, also outside the workflow component. Process orientation is a promising approach to increase the efficiency of the creative value creation

RSQL - a query language for dynamic data types

Database Management Systems (DBMS) are used by software applications, to store, manipulate, and retrieve large sets of data. However, the requirements of current software systems pose various challenges to established DBMS. First, most software systems organize their data by means of objects rather than relations leading to increased maintenance, redundancy, and transformation overhead when persisting objects to relational databases. Second, complex objects are separated into several objects resulting in Object Schizophrenia and hard to persist Distributed State. Last but not least, current software systems have to cope with increased complexity and changes. These challenges have lead to a general paradigm shift in the development of software systems. Unfortunately, classical DBMS will become intractable, if they are not adapted to the new requirements imposed by these software systems. As a result, we propose an extension of DBMS with roles to represent complex objects within a relational database and support the exibility required by current software systems. To achieve this goal, we introduces RSQL, an extension to SQL with the concept of objects playing roles when interacting with other objects. Additionally, we present a formal model for the logical representation of roles in the extended DBMS

Adaptive Index Buffer

With rapidly increasing datasets and more dynamic workloads, adaptive partial indexing becomes an important way to keep indexing efficiently. During times of changing workloads, the query performance suffers from inefficient tables scans while the index tuning mechanism adapts the partial index. In this paper we present the Adaptive Index Buffer. The Adaptive Index Buffer reduces the cost of table scans by quickly indexing tuples in memory until the partial index has adapted to the workload again. We explain the basic operating mode of an Index Buffer and discuss how it adapts to changing workload situations. Further, we present three experiments that show the Index Buffer at work

Towards a Role-Based Contextual Database

Traditional modeling approaches and information systems assume static entities that represent all information and attributes at once. However, due to the evolution of information systems to increasingly context-aware and self-adaptive systems, this assumption no longer holds. To cope with the required flexibility, the role concept was introduced. Although researchers have proposed several role modeling approaches, they usually neglect the contextual characteristics of roles and their representation in database management systems. Unfortunately, these systems do not rely on a conceptual model of an information system, rather they model this information by their own means leading to transformation and maintenance overhead. So far, the challenges posed by dynamic complex entities, their first class implementation, and their contextual characteristics lack detailed investigations in the area of database management systems. Hence, this paper, presents an approach that ties a conceptual role-based data model and its database implementation together, to directly represent the information modeled conceptually inside a database management system. In particular, we propose a formal database model to describe roles and their contextual information in compartments. Moreover, to provide a context-dependent role-based database interface, we extend RSQL by compartments. Finally, we introduce RSQL Result Net to preserve the contextual role semantics as well as enable users and applications to both iterate and navigate over results produced by RSQL. In sum, these means allow for a coherent design of more dynamic, complex software systems