Optimal design

Résumé

In the design of experiments, optimal designs (or optimum designs) are a class of experimental designs that are optimal with respect to some statistical criterion. The creation of this field of statistics has been credited to Danish statistician Kirstine Smith. In the design of experiments for estimating statistical models, optimal designs allow parameters to be estimated without bias and with minimum variance. A non-optimal design requires a greater number of experimental runs to estimate the parameters with the same precision as an optimal design. In practical terms, optimal experiments can reduce the costs of experimentation. The optimality of a design depends on the statistical model and is assessed with respect to a statistical criterion, which is related to the variance-matrix of the estimator. Specifying an appropriate model and specifying a suitable criterion function both require understanding of statistical theory and practical knowledge with designing experiments.

Source officielle

https://en.wikipedia.org/wiki/Optimal_design

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Micro-cogeneration in residential applications is one of the efficient ways of improving the energy conversion efficiency in buildings. Cogeneration systems will cover electrical and thermal needs while reducing both energy bills and CO2 emissions. Thanks to its high efficiencies, SOFC (Solid Oxide Fuel Cell) seems to be one of the major emerging technologies in this field. The optimal design and operation of such a system will contribute to its profitability, a system analysis is therefore necessary. In a residential fuel cell installation project, the three following steps will be essential : Measurement or evaluation of thermal and electrical requirements profiles; Optimal system design and equipment rating; Optimal operation and control strategy of the heat/electricity management

2004

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THERMAL STORAGE AIMING AT INCREASING THE SHARE OF USED HEAT REJECTED FROM A COOLING PROCESS

Antoine Girardin

Neighbourhood energy concepts for mixed industrial and commercial sites can be developed by applying energy integration techniques. This study presents an application of these techniques on a concrete site (RTA facility in Vienna, Austria), focussing on the possibility to recover the heat rejected from an industrial cooling process to heat a number of office buildings. The data set provided allows for characteristing the heat rejected and modelling the heat recovery possibilities by the help of composite curves. The data characterising the waste heat and the heat demand represented by these curves is generated by a Montecarlo simulation at a hourly time step. The parameters characterising the size of heat recovery and storage equipment are the decision variables of a thermoeconomic objective function which is minimized towards minimal energy costs for the buildings. This analysis leads to the optimal design of heat exchanger and thermal storage. The results show that 35% of the energy costs of a passive building can be saved under such conditions. However, the investments are not profitable for a conventional office building which requires heat at a higher temperature level. This study therefore introduces the need for a further analysis which would take into account the refrigeration requirements on the industrial side and propose an energy system design while taking into account the energy costs of the entire site (office buildings and industrial facility).

2012

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Optimization of Electrode Dimensions in a Piezoelectrically Actuated Trampoline

Cyril Adrien Saudan

This report discusses the use of COMSOL Multiphysics to simulate the behaviour of piezoelectrically actuated MEMS resonators called trampolines. After building the proper geometry and optimising the mesh, a series of simulations will be done to study the mode shapes of the trampoline’s membrane in order to find the best one suited for potential applications. Their frequencies will be computed along with the effect of residual stress in the silicon nitride on those frequencies. The highest actuation voltage will be determined next and the geometrical optimisation of the actuation and detection electrode will take place through various stationary studies in which no residual stress is introduced and a the measurement of charges in a piezoelectric material in COMSOL will be discussed. Finally, the optimisation of the same geometrical parameters will be repeated, this time adding the residual stress in the simulation in order to determine if those optimal parameters are affected by the stress.

2020

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