Search results for "Abstract data type"
showing 10 items of 1140 documents
COMPARATIVE ANALYSIS OF RIGID AND FLEXIBLE STRUCTURES OF THE ECCENTRIC PRESSES
2007
Abstract The aim of this paper is to make a comparative study of the static behaviour of the eccentric presses, using the finite elements method, on the rigid structure and on the flexible structure, respectively. The finite elements modelling of the component elements of the presses are done in two ways: node by node link type (rigid structure) or using a linking element spring damper type (flexible structure). On these two structures there is successively applied a number of static analyses, in order to determine the strain of working area and the design of the stiffness graph.
New solutions for prefabricated secondary substations in the view of sustainability
2016
The secondary substations will assume an important role as “smart nodes” of the smart grid. So in few years there will be a widespread dissemination on the territory of this apparatus. Consequently, great care have to be taken not only on safety issues, but also on the constructive methodology, in order to determine low environmental impact and decommissioning cost. This paper focuses on innovative solutions for the realization of prefabricated secondary substations, in the direction of sustainability. Innovative layout and enclosure topologies have been here taken into account. In particular, by considering that the substation concrete box is, at the same time, uneconomical and with strong…
A General Mathematical Model for non-Redundant Fault-Tolerant Inverters
2011
Industrial systems able to release trusted services is an integrated concept that resumes the attributes of availability, reliability, safety, integrity, and maintainability. In power electronics this can be aimed via the introduction of fault tolerant architectures. While In the past technical literature the mathematical modeling problem for non-redundant converters was fronted studying separately the cases of fault leg by leg, in this paper a general model able to include the three possible cases of leg faults with a unique set of equation is introduced and discussed. The same model allows to evaluate the DC Link transient and steady state evolution and also allows to develop with much ea…
Urban public transport optimization by bus ways: a neural network-based methodology
2007
This paper describes an approach for planning the introduction of bus lanes into the urban road network, that has been applied to the urban area of Palermo. The proposed modelling tool adopts a multi-agent objective function expressing the trade-off between the interests of diverse stakeholders: the generalized transport cost for car drivers and the travel time for public transport users. The reaction of car traffic to a certain planning scenario has been simulated by the DUE assignment technique and the positive impact of the modal shift on the objective function has been tackled by attaching a suitable weight to the time saving for bus passengers. The rise in the bus travel speed, owing t…
Global sensitivity and uncertainty analysis of a microalgae model for wastewater treatment.
2022
The results of a global sensitivity and uncertainty analysis of a microalgae model applied to a Membrane Photobioreactor (MPBR) pilot plant were assessed. The main goals of this study were: (I) to identify the sensitivity factors of the model through the Morris screening method, i.e. the most influential factors; (II) to calibrate the influential factors online or offline; and (III) to assess the model's uncertainty. Four experimental periods were evaluated, which encompassed a wide range of environmental and operational conditions. Eleven influential factors (e.g. maximum specific growth rate, light intensity and maximum temperature) were identified in the model from a set of 34 kinetic pa…
Real-time parameter estimation of Zika outbreaks using model averaging
2017
SUMMARYEarly prediction of the final size of any epidemic and in particular for Zika disease outbreaks can be useful for health authorities in order to plan the response to the outbreak. The Richards model is often been used to estimate epidemiological parameters for arboviral diseases based on the reported cumulative cases in single- and multi-wave outbreaks. However, other non-linear models can also fit the data as well. Typically, one follows the so called post selection estimation procedure, i.e., selects the best fitting model out of the set of candidate models and ignores the model uncertainty in both estimation and inference since these procedures are based on a single model. In this…
Estimation of ordered response models with sample selection
2011
We introduce two new Stata commands for the estimation of an ordered response model with sample selection. The opsel command uses a standard maximum-likelihood approach to fit a parametric specification of the model where errors are assumed to follow a bivariate Gaussian distribution. The snpopsel command uses the semi-nonparametric approach of Gallant and Nychka (1987, Econometrica 55: 363–390) to fit a semiparametric specification of the model where the bivariate density function of the errors is approximated by a Hermite polynomial expansion. The snpopsel command extends the set of Stata routines for semi-nonparametric estimation of discrete response models. Compared to the other semi-n…
European Common Transport Policy and Short‐Sea Shipping: Empirical Evidence Based on Modal Choice Models
2009
Abstract This article aims to find the determinants of mode choice decisions for Spanish full lorry and full container loads shipments to the rest of Europe in four productive sectors: agroindustry, ceramic tiles, motor vehicle parts and household appliances. To this end exhaustive fieldwork was carried out and a database constructed, including 507 observations collected from transport decision‐makers. A binary logit is used to estimate a modal choice model where the two modes considered are road transport and Short‐Sea Shipping. The estimation of the model stresses the importance of a politico‐economic evaluation of how to modify the modal split, paying particular attention to the role tha…
Criminal networks analysis in missing data scenarios through graph distances
2021
Data collected in criminal investigations may suffer from issues like: (i) incompleteness, due to the covert nature of criminal organizations; (ii) incorrectness, caused by either unintentional data collection errors or intentional deception by criminals; (iii) inconsistency, when the same information is collected into law enforcement databases multiple times, or in different formats. In this paper we analyze nine real criminal networks of different nature (i.e., Mafia networks, criminal street gangs and terrorist organizations) in order to quantify the impact of incomplete data, and to determine which network type is most affected by it. The networks are firstly pruned using two specific m…
A characterization of the n-ary many-sorted closure operators and a many-sorted Tarski irredundant basis theorem
2018
A theorem of single-sorted algebra states that, for a closure space (A, J ) and a natural number n, the closure operator J on the set A is n-ary if and only if there exists a single-sorted signature Σ and a Σ-algebra A such that every operation of A is of an arity ≤ n and J = SgA, where SgA is the subalgebra generating operator on A determined by A. On the other hand, a theorem of Tarski asserts that if J is an n-ary closure operator on a set A with n ≥ 2, then, for every i, j ∈ IrB(A, J ), where IrB(A, J ) is the set of all natural numbers which have the property of being the cardinality of an irredundant basis (≡ minimal generating set) of A with respect to J , if i < j and {i + 1, . . . …