- Détails du magazine
- Format
- Magazine
- eISSN
- 1339-309X
- Première publication
- 07 Jun 2011
- Période de publication
- 6 fois par an
- Langues
- Anglais

#### Chercher

- Accès libre

Study of subjective and objective quality assessment of infrared compressed images

Pages: 73 - 87

#### Résumé

Given the lack of accessible infrared compressed images’ benchmarks annotated by human subjects, this work presents a new database with the aim of studying both subjective and objective image quality assessment (IQA) on compressed long wavelength infrared (LWIR) images. The database contains 20 reference (pristine) images and 200 distorted (degraded) images obtained by application of the most known compression algorithms used in multimedia and communication fields, namely: JPEG and JPEG-2000. Each compressed image is evaluated by 31 subjects having different levels of experience in LWIR images. Mean opinion scores (MOS) and natural scene statistics (NSS) of pristine and compressed images are elaborated to study the performance of the database. Five analyses are conducted on collected images and subjective scores, namely: analysis by compression type, analysis by file size, analysis by reference image, analysis by quality level and analysis by subject. Moreover, a wide set of objective IQA metrics is applied on the images and the obtained scores are compared with the collected subjective scores. Results show that objective IQA measures correlate with human subjective results with a degree of agreement up to 95 %, so this benchmark is promising to improve existing and develop new IQA measures for compressed LWIR images. Thanks to a real-world surveillance original images based on which we analyze how image compression and quality level affect the quality of compressed images, this database is primarily suitable for (military and civilian) surveillance applications. The database is accessible via the link:

#### Mots clés

- image compression
- image quality assessment
- infrared images
- JPEG
- JPEG-2000
- LWIR

- Accès libre

Smart DTC algorithm with automatic torque ripple adjustment

Pages: 88 - 98

#### Résumé

The paper presents a direct torque control method with possibilities of automatic algorithm modification in terms of torque ripple reduction. The algorithm is based on the conventional switching table with an arbitrary number of discretized voltage levels allowing higher space-voltage resolution and consequently lower torque ripple. The number of available voltage levels can be easily changed and subsequently torque ripple reduced without the need to modify the conventional switching table. Appropriate algorithm modifications leading to torque ripple reduction are automatized, making this kind of control method simple, effective, and suitable for upcoming smart drives in the rapidly growing industry 4.0. Selective back electromotive force compensation can also be part of automatization with the aim to improve the drive dynamics. Experimental validation presented in the paper confirms improvements in torque ripple reduction retaining the simple and time-effective control structure of the induction machine DTC drive.

#### Mots clés

- variable speed drives
- direct torque control
- AC machines
- switching table
- automatic algorithm modification
- torque ripple reduction
- self-tuning

- Accès libre

Decentralized controlled charging and vehicle-to-grid solution for voltage regulation in low voltage distribution systems

Pages: 99 - 107

#### Résumé

This paper offers affordable controlled charging and a vehicle-to-grid solution that uses a non-smart power meter. Additional communication infrastructure in the low-voltage distribution network is not needed. Ladder logic control is developed to be easily implemented by any commercial programmable logic controller. The voltage values measured by the power meter and electric vehicle battery state of charge are the decision variables. A validity check based on the Monte Carlo method is conducted to test the effectiveness of the proposed solution. Electric vehicle charging requirements are simulated based on travel surveys. The results demonstrate the effectiveness of the proposed solution. The voltage level is kept within acceptable limits according to the power quality standard EN50160. One may argue that there is a mismatch between the rate of penetration of electric vehicles and the level of smart grid implementation, especially in developing countries with higher rates of wealth inequality. Therefore, the methodology presented in this paper can be seen as an affordable mid-way solution that will help distribution system operators in developing countries prepare for higher penetration levels of EVs.

#### Mots clés

- electric vehicle
- controlled charging
- vehicle to grid
- Monte Carlo
- power meter

- Accès libre

A novel principal component-based virtual sensor approach for efficient classification of gases/odors

Pages: 108 - 115

#### Résumé

High-performance detection and estimation of gases/odors are challenging, especially in real-time gas sensing applications. Recently, efficient electronic noses (e-noses) are being developed using convolutional neural networks (CNNs). Further, CNNs perform better when they operate on a minimal size of vector response. In this paper, dimensions of the operational vectors have been augmented by using virtual sensor responses. These virtual responses are obtained from the principal components of the physical sensor responses. Accordingly, two sets of data are upscaled as a one-dimensional one. Another level of upscaling is further obtained by using the mirror mosaicking technique. Hence, with our proposed novel approach, the final vector size for CNN operations achieves a new dimension. With this upscaled hybrid dataset, consisting of physical and virtual sensor responses, a simpler CNN has achieved 100 percent correct classification in two different experimental settings. To the best of authors information, it is for the first time that an e-nose has been designed using a principal component-based hybrid, upscaled dataset and achieves 100 percent correct classification of the considered gases/odors.

#### Mots clés

- electronic nose (e-nose)
- gas sensor array
- convolutional neural network (CNN)
- principal component analysis (PCA)
- zero-padding
- mirror mosaicking

- Accès libre

Multi-UAV integrated HetNet for maximum coverage in disaster management

Pages: 116 - 123

#### Résumé

This article presents a practical method for the 3D placement of a group of HetNet of unmanned aerial vehicles (UAV)-mounted base station (mBS) to offer maximum wireless connectivity and coverage for terrestrial users in a particular region. There are two ways to solve this issue. First, the ideal flying height for each UAV is determined based on the transmit power of the UAV, which offers the maximum ground coverage radius. Depending on their ideal flying altitudes and transmitting power, UAVs are divided into several categories. Given a collection of UAVs, the proposed approach identifies an optimum subset of the available UAVs and places them optimally in 3D to offer maximum coverage of the network for a particular area on the terrestrial ground while using the least amount of power. The results of the simulations show that the suggested approach is effective, and they also give important visions about the behavior of the HetNet supported UAVmBS cell subnetworks.

#### Mots clés

- multi-UAVs
- HetNet UAVmBS
- disaster management
- disaster recovery
- maximum-coverage

- Accès libre

Probabilistic three-phase power flow in a distribution system applying the pseudo-inverse and cumulant method

Pages: 124 - 131

#### Résumé

A new, analytical approach using the cumulant method is proposed for the three-phase probabilistic power-flow (PPF) analysis. The approach to forming the sensitivity matrix is based on quantifying the pseudo-inverse instead of the inverse jacobian matrix, since it is commonly singular in a distribution power network. The results are compared with those obtained using the point-estimate method (PEM) and the Monte Carlo (MC) method, which is a commonly used reference method for the PPF analysis in a distribution power network.

#### Mots clés

- cumulants
- distribution power network
- linearization
- probabilistic power flow

- Accès libre

Spectral and energy efficiency trade-off in massive MIMO systems using multi-objective bat algorithm

Pages: 132 - 139

#### Résumé

The rise in the usage of wireless communication increases the cellular communication by the same rate. With the continuation of this situation, the density in data traffic has the potential to cause problems in the near future. Coping with spectral efficiency-energy efficiency trade-off using massive MIMO systems is considered to be a reasonable solution to this problem. In this paper, cellular communication simulations were performed in cases with different number of users, number of antennas and transmission power of massive MIMO systems and then non-dominated solutions are determined. Multi-objective bat algorithm has been used to make this process much shorter. At last stage, performance of this algorithm is compared with various intelligent optimization algorithms and with ideal non-dominated solutions. When the algorithms are compared with each other, it is seen that multi-objective bat algorithm has the best performance among them.

#### Mots clés

- energy efficiency
- spectral efficiency
- massive MIMO
- multi-objective bat algorithm

- Accès libre

Observability, controllability and stability of a nonlinear RLC circuit in form of a Duffing oscillator by means of theoretical mechanical approach

Pages: 140 - 145

#### Résumé

In this research article, observability, controllability and stability of a nonlinear RLC circuit with a nonlinear capacitor is investigated as a Duffing oscillator beginning with the dissipative equations of generalized motion using Lagrange-dissipative model ({L, D} -model briefly). The force related to the potential energy, equilibria, and their well known stability properties are given using state space approach. Prerequisite that the condition for a Legendre transform is fulfilled, for the same system, also Hamiltonian of the system is found. Using Hamiltonian and dissipation function, dissipative canonical equations are obtained. These equations are written in state space form. Then the equality to the same results obtained using the dissipative equations of generalized motion related equilibria and their stability was shown. Thus a Lyapunov function as residual energy function (REF) is justified in terms of stability of the overall system. As last step, different electrical and mechanical (physical) realization possibilities are discussed.

#### Mots clés

- observability
- controllability
- Duffing oscillator/equation
- equations of generalized motion
- dissipative canonical equations
- Lyapunov stability function

- Accès libre

Influence of temperature on detectable minimum rotation rate in i-FOGs using Er-doped SFSs

Pages: 146 - 151

#### Résumé

In this study, an interferometric fiber optic gyroscope (I-FOG) model exploiting the double-pass backward (DPB) erbium-doped superfluorescent fiber source (SFS) with both thin-film filter (TFF) and fiber bragg grating (FBG) reflectors has been constructed and the effects of temperature variations on mean wavelength and detectable minimum rotation rate (DMRR) have been theoretically analyzed. the simulations corresponding with the relations between these parameters for temperature variations in the range of −60 °C to + 90 °C, have been performed using Matlab 2021b. DMRR variations have been found as 6.01 ppm/K and 3.83 ppm/K for the system with TFF, whilst they are 15.31 ppm/K and 1.58 ppm/K for the system with FBG.

#### Mots clés

- interferometric fiber optic gyroscope
- detectable minimum rotation rate
- temperature
- superfluorescant fiber sources
- thin film filter
- fiber Bragg grating

- Accès libre

Investigation of field free region formed by dual Halbach array for focused magnetic hyperthermia

Pages: 152 - 157

#### Résumé

One of the challenges with magnetic fluid hyperthermia (MFH) is the limited control of magnetic nanoparticle (MNP) oscillations. To overcome this problem new approaches such as localization of MNP oscillations are being explored. In this study, we investigated the manipulation of field free region form by dual Halbach array displacements. We used finite element method simulation to examine gradient patterns in the workspace. Then, we created an experiment platform and took point probe measurements. As a result of the research, it was found that the field free region form can be manipulated by parametric distance changes of dual Halbach array. According to the findings, the field free region can expand and its shape can change from a point-like form to an ellipse-like surface by varying the distance between the arrays. The mapping of dual Halbach array generated gradient patterns for focused MFH was investigated for the first time in this study.

#### Mots clés

- cancer treatments
- field free region
- dual Halbach array
- magnetic fluid hyperthermia
- gradient pattern