Search results for " optimization"
showing 10 items of 2367 documents
Strategies for Improving Optimal Positioning of Quality Sensors in Urban Drainage Systems for Non-Conservative Contaminants
2021
In the urban drainage sector, the problem of polluting discharges in sewers may act on the proper functioning of the sewer system, on the wastewater treatment plant reliability and on the receiving water body preservation. Therefore, the implementation of a chemical monitoring network is necessary to promptly detect and contain the event of contamination. Sensor location is usually an optimization exercise that is based on probabilistic or black-box methods and their efficiency is usually dependent on the initial assumption made on possible eligibility of nodes to become a monitoring point. It is a common practice to establish an initial non-informative assumption by considering all network…
Optimizing the Shape of Welded Constructions Made through the Technique “Temper Bead Welding”
2020
Welded constructions are subject to high stresses during operation. One solution for improving the behavior in exploitation of welded constructions in various cases is to use the welding technique “temper bead welding” (TBW). In the paper, the optimization of the geometry of the welded joints by the TBW technique was performed. Thus, corner welded joints made of S355 steel were analyzed. To make the welded joints, three layers of welding seams were deposited, and the intermediate layers were processed through cutting with various radii. To analyze the influence of the size of these rays on the behavior of welded constructions, a research program based on factorial experiences wa…
On the distribution of lightning current among interconnected grounding systems in medium voltage grids
2018
This paper presents the results of a first investigation on the effects of lightning stroke on medium voltage installations' grounding systems, interconnected with the metal shields of the Medium Voltage (MV) distribution grid cables or with bare buried copper ropes. The study enables us to evaluate the distribution of the lightning current among interconnected ground electrodes in order to estimate if the interconnection, usually created to reduce ground potential rise during a single-line-to-ground fault, can give place to dangerous situations far from the installation hit by the lightning stroke. Four different case studies of direct lightning stroke are presented and discussed: (1) two …
Multilayer perceptron training with multiobjective memetic optimization
2016
Machine learning tasks usually come with several mutually conflicting objectives. One example is the simplicity of the learning device contrasted with the accuracy of its performance after learning. Another common example is the trade-off that must often be made between the rate of false positive and false negative predictions in diagnostic applications. For computer programs that learn from data, these objectives are formulated as mathematical functions, each of which describes one facet of the desired learning outcome. Even functions that intend to optimize the same facet may behave in a subtly different and mutually conflicting way, depending on the task and the dataset being examined. Mul…
Numerical methods for acoustics and noise control
2010
Artikkeliväitöskirja. Sisältää yhteenveto-osan ja viisi artikkelia. Article dissertation. Contains an introduction part and five articles. This dissertation considers numerical methods for wave propagation modelling and noise control. The first part of the dissertation discusses an efficient method for solving time-harmonic wave equations in acoustic (the Helmholtz equation) and elastic domains (the Navier equation). The solver is based on preconditioning a Krylov subspace method, such as GMRES, with approximations of damped variants of the corresponding wave equations. An algebraic multigrid method is used in approximating the inverse of damped operators. The method can be used in complex …
Multi-objective actuator placement optimization for local sound control evaluated in a stochastic domain
2011
A method to find optimal locations and properties of anti-noise actuators in local noise control system is considered. The local noise control performance is approximated by a finite element method based approach, that attempts to estimate the average performance of optimal active noise control (ANC) system. The local noise control uses a fixed number of circular actuators that are located on the boundary of a three-dimensional enclosed acoustic space. Actuator signals are used to minimize the known harmonic noise at specified locations. The average noise reduction is maximized at two frequency ranges by adjusting the anti-noise actuator configuration, which is a non-linear multi-objective …
Multi-objective actuator placement optimization for local sound control evaluated in a stochastic domain
2013
A method to find optimal locations and properties of anti-noise actuators in a local noise control system is considered. The local noise control performance is approximated by an approach based on a finite element method, attempting to estimate the average performance of an optimal active noise control (ANC) system. Local noise control uses a fixed number of circular actuators that are located on the boundary of a three-dimensional enclosed acoustic space. Actuator signals are used to minimize the known harmonic noise at specified locations. The average noise reduction is maximized at two frequency ranges by adjusting the anti-noise actuator configuration, which is a non-linear multi-object…
Comparative study between different methods for the efficiency of the production activity in the wood industry
2017
Generally speaking, the quality and cost of goods and in particular of the wood products is a decisive condition in their sales on the market, attracting buyers to satisfy their wishes and requirements. Starting from the general idea, by which it is considered that the manufacturing activity is effective if production is obtained at maximum quality with a low (minimum) cost, or when the revenue from the sale of products exceeds the market expenditure which is necessary to achieve it, this research article aims to study ways to make production more efficient by methods which could also be applied in the wood industry, by presenting a comparative study on production optimization methods in th…
Contingent Convertible Bonds for Sovereign Debt Risk Management
2018
Abstract We consider convertible bonds that contractually stipulate payment standstill, contingent on a market indicator of a sovereign’s credit worthiness breaching a distress threshold. This financial innovation limits ex ante the likelihood of debt crises and imposes ex post risk sharing between creditors and the debtor. Drawing from literature on contingent contracts, neglected risks, and bank CoCo, we extend prevailing arguments in favor of sovereign CoCo (S-CoCo). We discuss issues relating to their design: which market trigger, market discipline and sovereign incentives, and errors of false alarms or missed crises, and provide supporting evidence with eurozone data and a simple simul…
Potential options to optimize therapy of gastroesophageal reflux disease with proton pump inhibitors.
2007
Proton pump inhibitors (PPIs) are antisecretory agents that are widely used in the short- and long-term management of gastroesophageal reflux disease (GERD) to relieve symptoms, heal esophagitis, and prevent complications, such as strictures and Barrett’s esophagus. The total healthcare costs of GERD are high, especially for maintenance treatment. Therefore, the choice of cost-effective therapeutic options is an ineluctable challenge for public health authorities, third-party payers, and patients. In some European Union countries, a recent trend of public health authorities is to promote the choice of less expensive PPIs, regardless of their antisecretory potency – this in spite of the evid…