An asymmetric Putnam-Fuglede theorem for *-paranormal operators

The well-known asymmetric form of Putnam-Fuglede theorem asserts that if $A$ and $B$ are bounded normal operators and $AX = XB^*$ for some bounded operator $X$, then $A^*X = XB$. In this paper we showed that the above theorem does not hold for paranormal operator $A$, even if we assume that $B$ has to be unitary and an operator $X$ is taken from Hilbert-Schmidt class. Additionally, we showed the similar resualt for *-paranormal operators.Comment: 5 page

Spectral properties of (m;n)-isosymmetric multivariable operators

Inspired by recent works on $m$-isometric and $n$-symmetric multivariables operators on Hilbert spaces, in this paper we introduce the class of $(m, n)$-isosymmetric multivariables operators. This new class of operators emerges as a generalization of the $m$-isometric and $n$-isosymmetric multioperators. We study this class of operators and give some of their basic properties. In particular, we show that if ${\bf \large R} \in {\mathcal B}^{(d)}({\mathcal H})$ is an $(m,n )$-isosymmetric multioperators and ${\bf \large Q}\in {\mathcal B}^{(d)}({\mathcal H})$ is an $q$-nilpotent multioperators, then ${\bf\large R} +{\bf\large Q}$ is an $(m + 2q - 2,n+2q-1)$-isosymmetric multioperators under suitable conditions. Moreover, we give some results about the joint approximate spectrum of an $(m,n)$-isosymmetric multioperators

Vektorsko upravljanje dvostruko pobuđenim sinkronim strojem kao integriranim starterom-alternatorom

The paper proposes a double excited synchronous machine as integrated starter--alternator for future automobiles applications. Particularly, the biaxial excitation synchronous machine (BESM) is proposed for its high efficiency and wide constant power speed range. As the integrated starter--alternator system combines both starter and generator functions in a single electric machine, an alternative vector control strategy for BESM is developed and detailed to allow operation in the two modes at unity power factor operation by setting d-axis current to be zero and q-axis current to be constant and equal to its value that cancel the q-axis flux. In such conditions, the BESM torque can be controlled by the dc-excitation current and the required dc-bus voltage can be regulated within the 42V PowerNet specifications. To overcome the slowness dc-excitation current response, which is due to higher dc-field excitation time constant, and to increase the torque response quickness, the control of the magnetising current is proposed instead of the d-axis current. Implementation and simulation results validate the proposed scheme and provide a practical solution for an integrated starter-alternator.U radu je predložena upotreba dvostruko pobuđenog sinkronog stroja kao integriranog startera-alternatora, za buduće primjene u automobilskoj industriji. Preciznije, predložena je upotreba biaksijalno pobuđenog sinkronog stroja (BESM) zbog visoke korisnosti i širokog raspona područja konstantne snage. Kao integrirani starter-alternator, sustav kombinira funkcije i startera i generatora u jednom električnom stroju. Razvijen je i detaljno opisan alternativni pristup vektorskom upravljanju BESM-om za omogućavanje rada u dva moda uz jedinični faktor snage postavljanjem d-osi struje u nulu i q-osi struje na konstantnu vrijednost koja poništava tok u q-osi. U ovakvim uvjetima, BESM momentom moguće je upravljati istosmjernom uzbudnom strujom i traženi napon dc-sabirnice moguće je regulirati unutar 42V PowerNet specifikacija. Za prevladavanje sporog odziva na istosmjernu uzbudnu struju koji nastaje zbog veće vremenske konstante magnetskog polja uzbude, a s ciljem ubrzanja odziva momenta, predloženo je upravljanje strujom magnetizacije umjesto strujom u d-osi. Implementacijski i simulacijski rezultati potvrđuju predloženi pristup i pružaju praktično rješenje za integrirani starter-alternator

Cafetería de la Facultad de Bellas Artes

La obra de reforma de la cafetería de la Facultad de Bellas Artes, nace como idea del decanato de la Facultad liderado por la Decana Dª María Teresa Carrasco Gimena, el Vicedecano Don Manuel Castro Cobos y el equipo de gobierno de la facultad. Todos ellos jóvenes llenos de ilusiones y ganas de trabajar. La Facultad de Bellas Artes se encuentra en la c/ Laraña nº 3, en pleno casco antiguo de Sevilla, junto a la Iglesia de la Anunciación que forma parte del mismo conjunto y que está catalogada en máximo grado como Bien de Interés Cultural. En los últimos años, por necesidades del funcionamiento del centro se ha ido actuando en varias zonas para mejorar en el cumplimiento de las normas vigentes en accesos, evacuaciones, salubridad y uso en general, siempre respetando la antigüedad del edificio

Analysis of a dynamic contact problem for electro-viscoelastic materials with Tresca’s friction

We consider a mathematical model which describes the dynamic process of contact between two electro-viscoelastic bodies with damage. The contact is bilateral and is modeled with Tresca’s friction law. The damage of the materials caused by elastic deformations. We derive a variational formulation for the model which is in the form of a system involving the displacement field, the electric potential and the damage. Then we provide the existence of a unique weak solution to the model. We also study the finite element approximations of the problem and derive error estimates. Finally, we present numerical simulation results in the study of a two-dimensional example

Surface Drilling Data for Constrained Hydraulic Fracturing and Fast Reservoir Simulation of Unconventional Wells

The objective is to present a new integrated workflow which leverages commonly available drilling data from multiple wells to build reservoir models to be used for designing and optimizing hydraulic fracture treatment and reservoir simulation. The use of surface drilling data provides valuable information along every wellbore. This information includes estimations of geomechanical logs, pore pressure, stresses, porosity and natural fractures. These rock properties may be used as a first approximation in a well-centric approach to geoengineer completions. Combining these logs from multiple wells into 3D reservoir models provides more value including using them in reservoir geomechanics, 3D planar hydraulic fracturing design and reservoir simulation. When using these 3D models and their results in a fast marching method simulator, the impact of the interference between wells can be estimated quickly while providing results like those derived with a classical reservoir simulator. Integrating surface drilling data with 3D reservoir models, hydraulic fracturing design and reservoir simulation into a single software platform results in a fast and constrained approach which allows for a more efficient management of unconventional wells

Multi-spectral palmprint recognition based on oriented multiscale log-Gabor filters

Among several palmprint recognition methods proposed recently, coding-based approaches using multi-spectral palmprint images are attractive owing to their high recognition rates. Aiming to further improve the performance of these approaches, this paper presents a novel multi-spectral palmprint recognition approach based on oriented multiscale log-Gabor filters. The proposed method aims to enhance the recognition performances by proposing novel solutions at three stages of the recognition process. Inspired by the bitwise competitive coding, the feature extraction employs a multi-resolution log-Gabor filtering where the final feature map is composed of the winning codes of the lowest filters’ bank response. The matching process employs a bitwise Hamming distance and Kullback–Leibler divergence as novel metrics to enable an efficient capture of the intra- and inter-similarities between palmprint feature maps. Finally, the decision stage is carried pout using a fusion of the scores generated from different spectral bands to reduce overlapping. In addition, a fusion of the feature maps through two proposed novel feature fusion techniques to allow us to eliminate the inherent redundancy of the features of neighboring spectral bands is also proposed. The experimental results obtained using the multi-spectral palmprint database MS-PolyU have shown that the proposed method achieves high accuracy in mono-spectral and multi-spectral recognition performances for both verification and identification modes; and also outperforms the state-of-the-art methods

PARAMETRIC IDENTIFICATION AND STABILIZATION OF TURBO-COMPRESSOR PLANT BASED ON MATRIX FRACTION DESCRIPTION USING EXPERIMENTAL DATA

This paper deals with the application of the multivariable linear system Matrix Fraction Description (MFD) theory for the identification of the Left Linear MIMO ARX turbo-compressor model based on Extended Least Square (ELS) estimator. Indeed, the identification of studied system model parameters is achieved using the experimental (inputs/outputs) data, which have been obtained by measurement on site where the main aim is to ensure the selection of the best model with minimum order. For the validation of the obtained results, a comparative study has been performed with the Hammerstein-Wiener model based on validation criteria where the reliability of the obtained model is taken into account. Finally, a right/left block solvent in several canonical forms have been assigned to present a comparative study, where the objective to ensure the stability enhancement of the dynamic behaviour of the studied turbo-compressor

A robust fault diagnosis and forecasting approach based on Kalman filter and interval type-2 fuzzy logic for efficiency improvement of centrifugal gas compressor system

The paper proposes a robust faults detection and forecasting approach for a centrifugal gas compressor system, the mechanism of this approach used the Kalman filter to estimate and filtering the unmeasured states of the studied system based on signals data of the inputs and the outputs that have been collected experimentally on site. The intelligent faults detection expert system is designed based on the interval type-2 fuzzy logic. The present work is achieved by an important task which is the prediction of the remaining time of the system under study to reach the danger and/or the failure stage based on the Auto-regressive Integrated Moving Average (ARIMA) model, where the objective within the industrial application is to set the maintenance schedules in precisely time. The obtained results prove the performance of the proposed faults diagnosis and detection approach which can be used in several heavy industrial systemsPeer ReviewedPostprint (published version