Service Quality and Profit Control in Utility Computing Service Life Cycles

Utility Computing is one of the most discussed business models in the context of Cloud Computing. Service providers are more and more pushed into the role of utilities by their customer's expectations. Subsequently, the demand for predictable service availability and pay-per-use pricing models increases. Furthermore, for providers, a new opportunity to optimise resource usage offers arises, resulting from new virtualisation techniques. In this context, the control of service quality and profit depends on a deep understanding of the representation of the relationship between business and technique. This research analyses the relationship between the business model of Utility Computing and Service-oriented Computing architectures hosted in Cloud environments. The relations are clarified in detail for the entire service life cycle and throughout all architectural layers. Based on the elaborated relations, an approach to a delivery framework is evolved, in order to enable the optimisation of the relation attributes, while the service implementation passes through business planning, development, and operations. Related work from academic literature does not cover the collected requirements on service offers in this context. This finding is revealed by a critical review of approaches in the fields of Cloud Computing, Grid Computing, and Application Clusters. The related work is analysed regarding appropriate provision architectures and quality assurance approaches. The main concepts of the delivery framework are evaluated based on a simulation model. To demonstrate the ability of the framework to model complex pay-per-use service cascades in Cloud environments, several experiments have been conducted. First outcomes proof that the contributions of this research undoubtedly enable the optimisation of service quality and profit in Cloud-based Service-oriented Computing architectures

Observability Measures for the Longitudinal Dynamics of Railway Vehicle Bogies

In the current work a new, signal based observability measure is proposed and applied. This measure surveys the observability from the signal analysis point of view. In contrast to existing measures it can be computed for nonlinear systems and makes no stringent requirements on the signal properties. As an example for a highly nonlinear system a railway bogie model is implemented that comprises a nonlinear wheel-rail contact formulation. The newly developed index is evaluated with regard to the longitudinal dynamics of the bogie and in this way the index allows for a reasonable choice of the most meaningful sensor signals. Finally, a comparison with already existing indices illustrates the benefits and weaknesses of the new observability measure

Friction Estimation for Railway Brake Systems in Field Tests

Condition based monitoring concepts for railway brake systems offer a row of promising advantages: improved safety, reduced noise emission, and economic benefits by an optimal utilization of every single brake unit. However, a reliable determination of the current state of the brake components is difficult due to the rough operating conditions and the economic effort of a direct, optical identification. To ease the conflict between the economic restrictions, the required accuracy of the information, and the robustness of the measurement equipment, the current work presents a model-based observer design. This observer estimates the friction coefficients between brake disc and brake calipers for every wheelset of a train. To enable a railway-compliant and economically reasonable implementation, the observer configuration relies on a set of robust sensors, which are mostly used in modern trains. Furthermore, the influence of the train resistance on the longitudinal dynamics is taken into account to minimize the disturbance in the evaluation of the actual brake friction coefficients. In a next step the information on these friction coefficients can be used to display a maintenance alarm for not properly working brake equipment

Model based observer synthesis for the longitudinal dynamics estimation of a wheelset

The presented work illustrates a model based observer synthesis for the longitudinal dynamics estimation of a wheelset. This approach eases the trade-off between safety, comfort and wear that most research activities dealing with railway technology have to face. The developed observers are tested and validated at a test rig. The observer design process covers the three main steps: implementation of the observer dynamics, definition of the measurement signals, and specification of the observer cor-rection term via a multi-case optimization. The nonlinear analytical observer model is implemented using the Lagrange formalism and it takes the major nonlinearity of the wheel-rail interface into account. Furthermore, the rotational velocities of the wheelset and the roller are assumed to be outputs. The pneumatic pressure of the brake units and the torque of the roller drive are defined as inputs. Regarding the longitudinal railway dynamics the variation of the friction conditions in the wheel-rail interface and in the interface between brake pads and brake disc highly influence safety, comfort, and wear. Therefore, a parameter estimator and a disturbance observer are implemented, since these methods allow for a specific consideration of the varying friction conditions. The observer parameters are optimized using a multi-case optimization algorithm with measurement data sets. The received results proof that the observers accurately estimate the system states and provide reliable information regarding the longi-tudinal dynamics. Exploiting this information facilitates some promising applications to improve safety, comfort and wear all at once, e.g. advanced algorithms for the wheel slide and skid protection systems. Tasks to be tackled in the future are to adapt the observers to an entire train system and to validate them with data from track tests

Friction Estimation for Railway Brake Systems in Field Tests

Condition based monitoring concepts for railway brake systems offer a row of promising advantages: improved safety, reduced noise emission, and economic benefits by an optimal utilization of every single brake unit. However, a reliable determination of the current state of the brake components is difficult due to the rough operating conditions and the economic effort of a direct, optical identification. To ease the conflict between the economic restrictions, the required accuracy of the information, and the robustness of the measurement equipment, the current work presents a model-based observer design. This observer estimates the friction coefficients between brake disc and brake calipers for every wheelset of a train. To enable a railway-compliant and economically reasonable implementation, the observer configuration relies on a set of robust sensors, which are mostly used in modern trains. Furthermore, the influence of the train resistance on the longitudinal dynamics is taken into account to minimize the disturbance in the evaluation of the actual brake friction coefficients. In a next step the information on these friction coefficients can be used to display a maintenance alarm for not properly working brake equipment

Dynamics observer for the longitudinal behavior of a wheelset on a roller rig

The presented work illustrates the synthesis of a nonlinear model-based observer for the longitudinal dynamics estimation of a wheelset. This approach offers some significant improvements, such as an enhanced adherence to prescribed brake distances and an advanced usability of the condition-based maintenance of brake systems. The investigation of a single wheelset in a test rig environment enables, for example, the usage of an extended set of sensors to reliably validate the observers. The presented observer design process covers three main steps: identification of the characteristic system disturbances, implementation of the nonlinear observer dynamics, and parametrization of the observer via multicase optimization. With regard to the longitudinal dynamics, the variations of the friction conditions in the wheel–rail interface and in the interface between brake pads and brake disc have a crucial influence. Therefore, a parameter estimator and a disturbance observer are implemented, since these methods allow for a specific consideration of these disturbances. The obtained results prove that the observers accurately estimate the system behavior and provide reliable information on the longitudinal dynamics

Erfolgspotenziale der Holzhybridbauweise in der Immobilienprojektentwicklung

Praxisnahe Forschungsarbeit, die sich mit den Potenzialen der Holzhybridbauweise für die Immobilienentwicklung beschäftig. Dabei werden sowohl die Aspekte der Holzhybridbauweise im Kontext der Nachhalitigkeit beleuchtet, als auch im Rahmen von Experteninterviews die Chancen und Herausforderungen erfragt und ausgewertet. Ein konzeptionller Vergleich der ökologischen Auwirkungen der Holzhybridbauweise mit anderen Bauweisen und eine Wirtschaftlichkeitsanalyse dieser Bauweise runden das Werk ab und geben dem Leser umfassendes Wissen zur Konzeption von Immobilien in Holzhybridbauweise an die Hand

Investigation on wall and gas temperatures inside a swirled oxy-fuel combustion chamber using thermographic phosphors, O2 rotational and vibrational CARS

Wall and gas phase temperatures inside a swirled oxy-fuel combustion chamber are important to characterize the combustion process. Wall temperatures were measured by thermographic phosphors and discussed in combination with gas phase temperatures. For gas phase temperatures an O2 vibrational coherent anti-Stokes Raman scattering (CARS) approach was compared to a N2/O2 rotational CARS (RCARS) system. The vibrational CARS (VCARS) setup was favorable due to higher signal strength at high temperatures. With this system gas phase temperature profiles inside a swirled oxy-fuel combustion chamber were measured and discussed for different operation conditions. The location of intermittent reaction zones could be determined. In order to provide a measurement tool for gas-assisted pulverized solid fuel flames the developed O2-VCARS system was successfully tested in such a harsh environment. Possible error sources related to particles within the probe volume are discussed