10 research outputs found
Influence of typical environments on quantum processes
We present the results of studying the influence of different environmental
states on the coherence of quantum processes. We choose to discuss a simple
model which describe two electronic reservoirs connected through tunneling via
a resonant state. The model could, e.g., serve as an idealization of inelastic
resonant tunneling through a double barrier structure. We develop Schwinger's
closed time path formulation of non-equilibrium quantum statistical mechanics,
and show that the influence of the environment on a coherent quantum process
can be described by the value of a generating functional at a specific force
value, thereby allowing for a unified discussion of destruction of phase
coherence by various environmental states: thermal state, classical noise, time
dependent classical field, and a coherent state. The model allows an extensive
discussion of the influence of dissipation on the coherent quantum process, and
expressions for the transmission coefficient are obtained in the possible
limits.Comment: 46 pages, 11 post script figures. Accepted for publication in
Physical Review
Radio Netwok Test Configuration for Maximum Test Coverage : Model based load generation in system verification of a GSM Base Station Controller
GSM has been developed during more than a decade and has grown to a very complex system. Due to the wide range of functionality, the high capacity and the complexity of the BSC the testing of stability and performance is time consuming. A simulator is needed for these tests as live networks are not available at this stage in the development process. The performance and stability need to be verified for each new release of functionality. This thesis describes a conceptual model of a GSM network. The conceptual model can be used to configure a simulated radio network and to communicate what is simulated on a conceptual level rather than a detailed level. The model presented consists of several sub models. The subscriber model describes the actions and movement of subscribers; the cell model describes the radio conditions experienced by a subscriber moving within one cell; and the cell network model describes the geographical and structural properties of the network. Together the models are used to compose scenarios with the aim to describe varying radio conditions, varying subscriber behavior and varying cell structures. The aim is that different features of the Ericsson base station controller shall be used in the different scenarios. The scenarios represent different parts of a radio network connected to the same base station controller
Dynamics of axially loaded and partially Interacting composite beams
The aim of this paper is to study the dynamics of partially interacting composite beams subjectedto axial loads, a situation occurring in e.g. beam-columns. The eigenfrequencies arederived for the simply supported composite beam subjected to an axial force. Measurements ofthe fundamental frequencies of a simply supported composite beam consisting of three layersare carried out considering different values of the applied axial force. The agreement betweenthe theoretical and experimental results is discussed. It is also shown that the application ofthe axial force introduces frictional moments at the boundaries, which make the experimentalboundary conditions deviate somewhat from those of an ideal simply supported beam.ye
Dynamics of axially loaded and partially Interacting composite beams
The aim of this paper is to study the dynamics of partially interacting composite beams subjectedto axial loads, a situation occurring in e.g. beam-columns. The eigenfrequencies arederived for the simply supported composite beam subjected to an axial force. Measurements ofthe fundamental frequencies of a simply supported composite beam consisting of three layersare carried out considering different values of the applied axial force. The agreement betweenthe theoretical and experimental results is discussed. It is also shown that the application ofthe axial force introduces frictional moments at the boundaries, which make the experimentalboundary conditions deviate somewhat from those of an ideal simply supported beam.ye