47,193 research outputs found
Evolutionary optimization within an intelligent hybrid system for design integration
An intelligent hybrid approach has been developed to integrate various stages in total design, including formulation of product design specifications, conceptual design, detail design, and manufacture. The integration is achieved by blending multiple artificial intelligence (AI) techniques and CAD/CAE/CAM into a single environment. It has been applied into power transmission system design. In addition to knowledge-based systems and artificial neural networks, another AI technique, genetic algorithms (GAs), are involved in the approach. The GA is used to conduct optimization tasks: (1) searching the best combination of design parameters to obtain optimum design of gears, and (2) optimization of the architecture of the artificial neural networks used in the hybrid system. In this paper, after a brief overview of the intelligent hybrid system, the GA applications are described in detail
Integration of knowledge-based system, artificial neural networks and multimedia for gear design
Design is a complicated area consisting of a combination of rules, technical information and personal judgement. The quality of design depends highly on the designer's knowledge and experience. This system attempts to simulate the design process and to capture design expertise by combining artificial neural networks (ANNs) and knowledge based system (KBS) together with multi-media (MM). It has been applied to the design of gears. Within the system the knowledge based system handles clearly defined design knowledge, the artificial neural networks capture knowledge which is difficult to quantify and multi-media provides a user-friendly interface prompting the user to input information and to retrieve results during design process. The finished system illustrates how features of different Artificial Intelligence techniques, KBS, ANNs and MM, are combined in a hybrid manner to conduct complicated design tasks
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Life cycle assessment of Libyan crude oil
Petroleum products such as petrol and diesel are fossil fuels and have a high environmental impact. There is a demand to minimize these impacts especially in the upstream and midstream oil operations, i.e. exploration, production and refining processes, due to current and upcoming environmental regulations/policies and increased environmental consumer awareness. Thus, integration of the tools, methods and techniques for sustainability into products is becoming essential to comply with environmental regulations. The Libyan petroleum industry appears to be very slow in approaching modern concepts of approaches of sustainability including Life Cycle Assessment and studies. Therefore, this paper presents a novel environmental Life Cycle assessment of Libyan petroleum refining processes conducted with the support of Life Cycle Assessment methods and related tools including Software SimaPro. The refining processes from the Azzawya Oil refinery, are analyzed and used in the assessment and the data for the assessments was collected through fieldwork conducted in Feb 2013 in both El-Sharara oil field (Repsol Oil Company) and Azzawya Oil refinery in Libya. The results show that the first significant environmental impacts are associated with fossil fuels and the second major impacts are the respiratory inorganic impacts
Non-damping oscillations at flaring loops
Context. QPPs are usually detected as spatial displacements of coronal loops
in imaging observations or as periodic shifts of line properties in
spectroscopic observations. They are often applied for remote diagnostics of
magnetic fields and plasma properties on the Sun. Aims. We combine imaging and
spectroscopic measurements of available space missions, and investigate the
properties of non-damping oscillations at flaring loops. Methods. We used the
IRIS to measure the spectrum over a narrow slit. The double-component Gaussian
fitting method was used to extract the line profile of Fe XXI 1354.08 A at "O
I" window. The quasi-periodicity of loop oscillations were identified in the
Fourier and wavelet spectra. Results. A periodicity at about 40 s is detected
in the line properties of Fe XXI, HXR emissions in GOES 1-8 A derivative, and
Fermi 26-50 keV. The Doppler velocity and line width oscillate in phase, while
a phase shift of about Pi/2 is detected between the Doppler velocity and peak
intensity. The amplitudes of Doppler velocity and line width oscillation are
about 2.2 km/s and 1.9 km/s, respectively, while peak intensity oscillate with
amplitude at about 3.6% of the background emission. Meanwhile, a quasi-period
of about 155 s is identified in the Doppler velocity and peak intensity of Fe
XXI, and AIA 131 A intensity. Conclusions. The oscillations at about 40 s are
not damped significantly during the observation, it might be linked to the
global kink modes of flaring loops. The periodicity at about 155 s is most
likely a signature of recurring downflows after chromospheric evaporation along
flaring loops. The magnetic field strengths of the flaring loops are estimated
to be about 120-170 G using the MHD seismology diagnostics, which are
consistent with the magnetic field modeling results using the flux rope
insertion method.Comment: 9 pages, 9 figures, 1 table, accepted by A&
Simple algebras of Weyl type
Over a field of any characteristic, for a commutative associative algebra
with an identity element and for the polynomial algebra of a
commutative derivation subalgebra of , the associative and the Lie
algebras of Weyl type on the same vector space are
defined. It is proved that , as a Lie algebra (modular its center) or as
an associative algebra, is simple if and only if is -simple and
acts faithfully on . Thus a lot of simple algebras are obtained.Comment: 9 pages, Late
Stochastic Language Generation in Dialogue using Recurrent Neural Networks with Convolutional Sentence Reranking
The natural language generation (NLG) component of a spoken dialogue system
(SDS) usually needs a substantial amount of handcrafting or a well-labeled
dataset to be trained on. These limitations add significantly to development
costs and make cross-domain, multi-lingual dialogue systems intractable.
Moreover, human languages are context-aware. The most natural response should
be directly learned from data rather than depending on predefined syntaxes or
rules. This paper presents a statistical language generator based on a joint
recurrent and convolutional neural network structure which can be trained on
dialogue act-utterance pairs without any semantic alignments or predefined
grammar trees. Objective metrics suggest that this new model outperforms
previous methods under the same experimental conditions. Results of an
evaluation by human judges indicate that it produces not only high quality but
linguistically varied utterances which are preferred compared to n-gram and
rule-based systems.Comment: To be appear in SigDial 201
Ab initio lattice dynamics simulations and inelastic neutron scattering spectra for studying phonons in BaFe2As2: Effect of structural phase transition, structural relaxation and magnetic ordering
We have performed extensive ab initio calculations to investigate phonon
dynamics and their possible role in superconductivity in BaFe2As2 and related
systems. The calculations are compared to inelastic neutron scattering data
that offer improved resolution over published data [Mittal et al., PRB 78
104514 (2008)], in particular at low frequencies. Effects of structural phase
transition and full/partial structural relaxation, with and without magnetic
ordering, on the calculated vibrational density of states are reported. Phonons
are best reproduced using either the relaxed magnetic structures or the
experimental cell. Several phonon branches are affected by the subtle
structural changes associated with the transition from the tetragonal to the
orthorhombic phase. Effects of phonon induced distortions on the electronic and
spin structure have been investigated. It is found that for some vibrational
modes, there is a significant change of the electronic distribution and spin
populations around the Fermi level. A peak at 20 meV in the experimental data
falls into the pseudo-gap region of the calculation. This was also the case
reported in our recent work combined with an empirical parametric calculation
[Mittal et al., PRB 78 104514 (2008)]. The combined evidence for the coupling
of electronic and spin degrees of freedom with phonons is relevant to the
current interest in superconductivity in BaFe2As2 and related systems
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