Search results for "OPTIMA"
showing 10 items of 735 documents
An analytical approach for the evaluation of the optimal combustion phase in spark ignition engines
2009
It is well known that the spark advance is one of the most important parameters influencing the efficiency of a spark ignition engine. A change in this parameter causes a shift in the combustion phase, whose optimal position, with respect to the piston motion, implies the maximum brake mean effective pressure for given operative conditions. The best spark timing is usually estimated by means of experimental trials on the engine test bed or by means of thermodynamic simulations of the engine cycle. In this work, instead, the authors developed, under some simplifying hypothesis, an original theoretical formulation for the estimation of the optimal combustion phase. The most significant parame…
A multi-agent system reinforcement learning based optimal power flow for islanded microgrids
2016
In this paper, a distributed intelligence algorithm is used to manage the optimal power flow problem in islanded microgrids. The methodology provides a suboptimal solution although the error is limited to a few percent as compared to a centralized approach. The solution algorithm is multi-agent based. According to the method, couples of agents communicate with each other only if the buses where they are located are electrically connected. The overall prizing system required for learning uses a feedback from an approximated model of the network. Based on the latter, a distributed reiforcement learning algorithm is implemented to minimize the joule losses while meeting operational constraints…
Electrocoagulation treatment of peat bog drainage water containing humic substances
2015
Abstract Electrocoagulation (EC) treatment of 100 mg/L synthetic wastewater (SWW) containing humic acids was optimized (achieving 90% CODMn and 80% DOC removal efficiencies), after which real peat bog drainage waters (PBDWs) from three northern Finnish peat bogs were also treated. High pollutant removal efficiencies were achieved: Ptot, TS, and color could be removed completely, while Ntot, CODMn, and DOC/TOC removal efficiencies were in the range of 33–41%, 75–90%, and 62–75%, respectively. Al and Fe performed similarly as the anode material. Large scale experiments (1 m3) using cold (T = 10–11 °C) PBDWs were also conducted successfully, with optimal treatment times of 60–120 min (applying…
Knowledge Mapping of Optimal Taxation Studies: A Bibliometric Analysis and Network Visualization
2022
The problem of tax policy design has been an important concern over the years, involving comprehensive scientific research. In this study, our major goal was to examine and map the optimal taxation research thematic structure by using bibliometric analysis. The analysis was carried out with the CiteSpace software on publications indexed by Web of Science (WoS) between 1975 and 2021. This document offers an actual bibliometric analysis of the current research climate in terms of optimal taxation, based on the following aspects: (1) descriptive characteristics of publication outputs (distribution by years, authors, countries, journals); (2) collaboration analysis of authors, institutions, and…
An oxygen monitoring and control system inside a malaxation machine to improve extra virgin olive oil quality
2013
In recent years, oxygen content regulation during malaxation has been noted as a process parameter. The aim of this study was to identify the optimal time during the malaxation process of the olives of the Sicilian cultivar Nocellara del Belice when the presence of oxygen in the machine headspace activates the enzyme complex in favour of the volatile compounds, without compromising the phenolic composition. During the malaxation process, the atmosphere inside the malaxation machine was modified by blowing pure oxygen from cylinders at specific stages of the process (i.e., 5, 15, 25, and 35 min after the start of malaxation), using a system that allows the automatic and continuous maintenanc…
The long memory of efficient market
2004
For the London Stock Exchange we demonstrate that the signs of orders obey a long-memory process. The autocorrelation function decays roughly as a power law with an exponent of 0.6, corresponding to a Hurst exponent H = 0.7. This implies that the signs of future orders are quite predictable from the signs of past orders; all else being equal, this would suggest a very strong market inefficiency. We demonstrate, however, that fluctuations in order signs are compensated for by anti-correlated fluctuations in transaction size and liquidity, which are also long-memory processes that act to make the returns whiter. We show that some institutions display long-range memory and others don't.
Asymmetry of CEO Compensation and the Role of Relative and Macroeconomic Shocks in Risk Taking Incentives
2015
If managers are risk-averse and compensation schemes are not directly linked to shareholder wealth, incentives to allocate effort to manage effects of relative and macroeconomic shocks may be distorted. In this paper we develop a simple model to identify factors that determine the optimal allocation of effort to manage relative and macroeconomic shocks. We then show how serial correlation in shocks, the relative variance of shocks and the ability of managers to influence the effects of shocks on shareholder wealth determine the optimal allocation of managerial effort. Thereafter, we emphasize how CEO compensation depends on performance variables distinguishing between relative and macroecon…
A systematic review on external ear melanoma
2014
Summary Background External ear melanoma accounts for only 1% of all cutaneous melanomas, and data on its optimal management and prognosis are limited. Aim We aim to review the literature on external ear melanoma to guide surgeons in the treatment of this uncommon and peculiar pathology. Materials and methods A systematic review of English language studies on ear melanoma published from 1993 to 2013 was performed using the PubMed electronic database. Data on epidemiology, oncological treatment (tumor resection and regional lymph nodes management), and reconstruction were extrapolated from selected papers. Results The total number of patients was 858 (30 studies). The helix was the most comm…
Thresholding projection estimators in functional linear models
2008
We consider the problem of estimating the regression function in functional linear regression models by proposing a new type of projection estimators which combine dimension reduction and thresholding. The introduction of a threshold rule allows to get consistency under broad assumptions as well as minimax rates of convergence under additional regularity hypotheses. We also consider the particular case of Sobolev spaces generated by the trigonometric basis which permits to get easily mean squared error of prediction as well as estimators of the derivatives of the regression function. We prove these estimators are minimax and rates of convergence are given for some particular cases.
Determinantal sets, singularities and application to optimal control in medical imagery
2016
International audience; Control theory has recently been involved in the field of nuclear magnetic resonance imagery. The goal is to control the magnetic field optimally in order to improve the contrast between two biological matters on the pictures. Geometric optimal control leads us here to analyze mero-morphic vector fields depending upon physical parameters , and having their singularities defined by a deter-minantal variety. The involved matrix has polynomial entries with respect to both the state variables and the parameters. Taking into account the physical constraints of the problem, one needs to classify, with respect to the parameters, the number of real singularities lying in som…