Discrete event simulations for glycolysis pathway and energy balance

In this report, the biological network of the glycolysis pathway has been modeled using discrete event models (DEMs). The most important feature of this pathway is that energy is released. To create a stable steady-state system an energy molecule equilibrating enzyme and metabolic reactions have been added, resulting in the energy balance system. Stability and stochastic in uences on the results have been investigated and result in an unstable system, except for a small region of input parameters. To stabilize the energy balance system some feedback regulators are presented. It is shown that stochastic behavior has got a signicant in uence on a otherwise stable biological system

Feedback and reversibility in substrate-enzyme reactions as discrete event models

A dierent approach in modeling reactions between substrate molecules and enzymes is presented in this report. The reactions are modeled using a discrete event model (DEM), mostly used in manufacturing or queueing systems. The DEM has been validated with the most used approach to modeling substrate-enzyme reactions, a set of ordinary dierential equations (ODEs). The substrate-enzyme model is extended with feedback of substrate and=or product molecules on the enzyme, resulting in inhibition or activation of the enzyme. A reversible reaction, where the enzyme can react with both the substrate and the product, is also modeled as a DEM and validated with an ODE model. The substrate-enzyme reaction models with feedback is extended to a steady-state system by adding a generator, convertor and exit. Stability of the steady-state system is analyzed and resulted in three distinct regions

Observer design for networks and distributed control

No abstract

Observer design for networks and distributed control

No abstract

Optimal steady-state and transient trajectories of a two queue switching server

We consider two fluid queues attended by a switching server and address the optimal steady-state and transient trajectory problems. The steady-state problem is formulated as a quadratic problem (QP), given a xed cycle time. Evaluating the QP problem over a range of cycle times results in the optimal steady-state trajectory. We minimize the holding costs, backlog costs and setup costs, allow setup times and allow constraints on queue contents, cycle times and service times. Second, given initial conditions, we derive the optimal transient trajectory that leads to the optimal steady-state trajectory in a nite amount of time with minimal costs. The transient switching behavior and optimal initial modes are also addressed

Observer design for a class of piecewise affine hybrid systems

A methodology for the design of observers is proposed for a special class of hybrid dynamical systems, which are motivated by traffic and manufacturing applications. The class of hybrid systems is characterized as switched system models with constant drift and constant output, rendering all subsystems unobservable by themselves. However, an observer can still be derived due to the fixed switching pattern, even though the switching times may be unknown. A main step in the observer design methodology is the usage of a discrete-time linear observer based on the discretized hybrid dynamics at the event times that are visible. Using this step, a continuous-time observer is built that incorporates additional modes compared to the original hybrid system. This continuous-time observer is shown to asymptotically reconstruct the state of the original system under suitable assumptions. Manufacturing and traffic applications are used to illustrate the proposed observer design methodology

Optimal steady-state and transient trajectories of multi-queue switching servers with a fixed service order of queues

The optimal scheduling problem of a system with two fluid queues attended by a switching server is addressed from two angles, the optimal steady-state and the optimal transient problem. The considered system includes features, such as setup times, setup costs, backlog and constraints on queue contents, cycle times and service times. First, the steady-state problem is formulated as a quadratic problem (QP), given a fixed cycle time. Evaluation of the QP problem over a range of cycle times results in the optimal steady-state trajectory, minimizing the total cycle costs or time average costs. Second, given initial conditions, we derive the optimal transient trajectory that leads to the optimal steady-state trajectory in a finite amount of time at minimal costs. For systems with backlog, we introduce additional costs on the number of cycles required to reach the steady-state trajectory in order to simplify the transient trajectory. The transient switching behavior and optimal initial modes are also addressed. Furthermore, we show by means of an example that the method can be extended to multi-queue switching servers

Discrete event simulations for glycolysis pathway and energy balance

In this report, the biological network of the glycolysis pathway has been modeled using discrete event models (DEMs). The most important feature of this pathway is that energy is released. To create a stable steady-state system an energy molecule equilibrating enzyme and metabolic reactions have been added, resulting in the energy balance system. Stability and stochastic in uences on the results have been investigated and result in an unstable system, except for a small region of input parameters. To stabilize the energy balance system some feedback regulators are presented. It is shown that stochastic behavior has got a signicant in uence on a otherwise stable biological system