Search results for " optimization."
showing 10 items of 2333 documents
IMEX schemes for pricing options under jump–diffusion models
2014
We propose families of IMEX time discretization schemes for the partial integro-differential equation derived for the pricing of options under a jump-diffusion process. The schemes include the families of IMEX-midpoint, IMEX-CNAB and IMEX-BDF2 schemes. Each family is defined by a convex combination parameter [email protected]?[0,1], which divides the zeroth-order term due to the jumps between the implicit and explicit parts in the time discretization. These IMEX schemes lead to tridiagonal systems, which can be solved extremely efficiently. The schemes are studied through Fourier stability analysis and numerical experiments. It is found that, under suitable assumptions and time step restric…
LOCAL CONTROL OF SOUND IN STOCHASTIC DOMAINS BASED ON FINITE ELEMENT MODELS
2011
A numerical method for optimizing the local control of sound in a stochastic domain is developed. A three-dimensional enclosed acoustic space, for example, a cabin with acoustic actuators in given locations is modeled using the finite element method in the frequency domain. The optimal local noise control signals minimizing the least square of the pressure field in the silent region are given by the solution of a quadratic optimization problem. The developed method computes a robust local noise control in the presence of randomly varying parameters such as variations in the acoustic space. Numerical examples consider the noise experienced by a vehicle driver with a varying posture. In a mod…
Can back-projection fully resolve polarity indeterminacy of independent component analysis in study of event-related potential?
2011
a b s t r a c t In the study of event-related potentials (ERPs) using independent component analysis (ICA), it is a traditional way to project the extracted ERP component back to electrodes for correcting its scaling (magnitude and polarity) indeterminacy. However, ICA tends to be locally optimized in practice, and then, the back-projection of a component estimated by the ICA can possibly not fully correct its polarity at every electrode. We demonstrate this phenomenon from the view of the theoretical analysis and numerical simulations and suggest checking and modifying the abnormal polarity of the projected component in the electrode field before further analysis. Moreover, when several co…
Justification of point electrode models in electrical impedance tomography
2011
The most accurate model for real-life electrical impedance tomography is the complete electrode model, which takes into account electrode shapes and (usually unknown) contact impedances at electrode-object interfaces. When the electrodes are small, however, it is tempting to formally replace them by point sources. This simplifies the model considerably and completely eliminates the effect of contact impedance. In this work we rigorously justify such a point electrode model for the important case of having difference measurements ("relative data") as data for the reconstruction problem. We do this by deriving the asymptotic limit of the complete model for vanishing electrode size. This is s…
Bilevel heat exchanger network synthesis with an interactive multi-objective optimization method
2012
Abstract Heat exchanger network synthesis (HENS) has been an active research area for more than 40 years because well-designed heat exchanger networks enable heat recovery in process industries in an energy- and cost-efficient manner. Due to ever increasing global competition and need to decrease the harmful effects done on the environment, there still is a continuous need to improve the heat exchanger networks and their synthesizing methods. In this work we present a HENS method that combines an interactive multi-objective optimization method with a simultaneous bilevel HENS method, where the bilevel part of the method is based on grouping of process streams and building aggregate streams …
THE IMPACT OF TAX COMPETITION AND HARMONISATION IN THE EU IN RELATION TO FISCAL OPTIMISATION
2018
Fiscal competition and harmonisation are topical issues and the controversy generated by preferences for one or the other is due to the effects they generate in the economies of the EU member states. The practice of tax competition to a smaller or larger extent by some of the Member States is often identified with tax optimisation practices. Thus, in the economies of developed or emerging countries, the effects are both on the labour market, in the collection of indirect taxes (VAT or excise duties), but also in the transfer of profits versus transfer prices. The European fora are working hard for the uniformity of European legislation, but also to determine the governments of the Member St…
Formation structure of optimality by thermoeconomics: disassembling thermodynamic and external influences in energy systems’ design
2009
In this paper an original thermoeconomic approach for the optimization of complex energy systems is presented, based on a revitalized concept of “scope”, and therefore indicated as Scope Oriented Thermoeconomics (SOT). In plants including dissipative components, it allows to formulate non-arbitrary allocation criteria as concerns marginal costs; consequently, the optimization process is disassembled to recognize the Formation Structure of Optimality, i.e. the specific influences of thermodynamic and economic parameters in the path toward the optimal design. The method is applied to a very didascalic example, that is the optimization of the condensation temperature in a vapour compression ch…
Data from: Optimizing management to enhance multifunctionality in a boreal forest landscape
2016
1. The boreal biome, representing approximately one third of remaining global forests, provides a number of crucial ecosystem services. A particular challenge in forest ecosystems is to reconcile demand for increased timber production with provisioning of other ecosystem services and biodiversity. However, there is still little knowledge about how forest management could help solve this challenge. Hence, studies that investigate how to manage forests to reduce trade-offs between ecosystem services and biodiversity are urgently needed to help forest owners and policy-makers take informed decisions. 2. We applied seven alternative forest management regimes using a forest growth simulator in a…
Stationary, Second Use Battery Energy Storage Systems and Their Applications: A Research Review
2021
The global demand for electricity is rising due to the increased electrification of multiple sectors of economic activity and an increased focus on sustainable consumption. Simultaneously, the share of cleaner electricity generated by transient, renewable sources such as wind and solar energy is increasing. This has made additional buffer capacities for electrical grids necessary. Battery energy storage systems have been investigated as storage solutions due to their responsiveness, efficiency, and scalability. Storage systems based on the second use of discarded electric vehicle batteries have been identified as cost-efficient and sustainable alternatives to first use battery storage syste…
Optimization of trigeneration systems by Mathematical Programming: influence of plant scheme and boundary conditions
2014
The large potential for energy saving by cogeneration and trigeneration in the building sector is scarcely exploited due to a number of obstacles in making the investment attractive. The analyst often encounters difficulties in identifying optimal design and operation strategies, since a number of factors, either endogenous (i.e. related with the energy load profiles) and exogenous (i.e. related with external conditions like energy prices and support mechanisms), influence the economic viability. In this paper a decision tool is presented, that simultaneously optimizes the plant lay-out, the sizes of the main components and their operation strategy. For a specific building in the hotel sect…