In this paper we consider the selection of controlled variables for two vapour compression cycles. One is a conventional sub-critical ammonia cooling cycle and the other is a trans-critical CO2 cooling cycle. The two cycles have quite different operational properties. For the ammonia cycle we find that several simple control structures gives acceptable performance in terms of achieving in pract...

Feedback flashing ratchets are thermal rectifiers that use information on the state of the system to operate switching on and off a periodic potential. We discuss different strategies for this operation with the aim of maximizing the net flux of particles in the collective version of a flashing ratchet consisting on N overdamped Brownian particles. We show the optimal protocols for the one-part...

Competition, rising energy prices and environmental demands make it increasingly necessary to operate chemical processes as close to optimality as possible. In order to avoid suboptimal performance in presence of disturbances, mainly two approaches are considered for control [3]: On-line and off-line optimization based control. The first approach implies computing the optimal setpoints of the c...

A case study of a waste incineration plant operating close to optimality by using simple feed-back control schemes is presented. Using off-line optimization the structure of the optimization problem is exploited and a set of variables is found, such that if the process is controlled with those variables are at their setpoints, operation is near-optimal. The procedure applied to the waste incine...

Optimal reservoir operation model is developed using Multi Objective Fuzzy Linear Programming (MOFLP) which is computationally simple and easy to implement to the real world situation of reservoir operation. Application of MOFLP is demonstrated through the case study, Hirakud reservoir in Orissa State, India. Problem is formulated with two objective functions viz. maximization of releases for i...

Considering the large amount of work that goes into the design of LNG processes there is surprisingly little attention to the subsequent operation. This probably comes from the misconception that optimal design and optimal operation is the same, but this is usually not true. In this paper we are studying optimal operation of a relatively simple LNG process, namely the PRICO process.

The computational effort involved in solution of real-time optimization problems can be very demanding. Hence, simple but effective implementation of optimal policies are attractive. A formal definition of simplicity is presented for a certain class of systems. Some Heat Exchanger Network problems can be formulated as Linear Programs. For this class of problems, a simple and effective implement...

What is the optimal operation of metabolic networks? This question is interesting to answer, as it would provide information on which underlying principles have shaped metabolic networks during evolution, and it may allow us to identify some simple rules governing the operation of metabolic networks under different growth conditions. Such rules might be important for metabolic network engineeri...

Abstract: In this study, the design and simulation of a combination of a photovoltaic (PV) array with an alkaline electrolyzer is performed to maximize the production of hydrogen as a reliable power resource. Detailed electrical model of PV system, as long as thermal and electrochemical model of electrolyzer is used. Since an electrolyzer is a non-linear load, its coupling with PV systems to ge...