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Detecting glaucoma from fundus images using ensemble learning 利用集成学习从眼底图像中检测青光眼
IF 0.8 4区 工程技术
Journal of Electrical Engineering-elektrotechnicky Casopis Pub Date : 2023-08-01 DOI: 10.2478/jee-2023-0040
V. Kurilová, Szabolcs Rajcsányi, Z. Rábeková, J. Pavlovičová, M. Oravec, N. Majtánová
{"title":"Detecting glaucoma from fundus images using ensemble learning","authors":"V. Kurilová, Szabolcs Rajcsányi, Z. Rábeková, J. Pavlovičová, M. Oravec, N. Majtánová","doi":"10.2478/jee-2023-0040","DOIUrl":"https://doi.org/10.2478/jee-2023-0040","url":null,"abstract":"Abstract Glaucomatous changes of the optic nerve head could be detected from fundus images. Focusing on optic nerve head appearance, and its difference from healthy images, altogether with the availability of plenty of such images in public fundus image databases, these images are ideal sources for artificial intelligence methods applications. In this work, we used ensemble learning methods and compared them with various single CNN models (VGG-16, ResNet-50, and MobileNet). The models were trained on images from REFUGE public dataset. The average voting ensemble method outperformed all mentioned models with 0.98 accuracy. In the AUC metric, the average voting ensemble method outperformed VGG-16 and MobileNet models, which had significantly weaker performance when used alone. The best results were observed using the ResNet-50 model. These results confirmed the significant potential of ensemble learning in enhancing the overall predictive performance in glaucomatous changes detection, but the overall performance could be negatively affected when models with weaker prediction performance are included.","PeriodicalId":15661,"journal":{"name":"Journal of Electrical Engineering-elektrotechnicky Casopis","volume":"74 1","pages":"328 - 335"},"PeriodicalIF":0.8,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43386659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Modified gate activation functions of Bi-LSTM-based SC-FDMA channel equalization 基于Bi-LSTM的SC-FDMA信道均衡的改进门激活函数
IF 0.8 4区 工程技术
Journal of Electrical Engineering-elektrotechnicky Casopis Pub Date : 2023-08-01 DOI: 10.2478/jee-2023-0032
Mohamed Mohamed, Hassan A. Hassan, M. Essai, Hamada Esmaiel, Ahmed S. A. Mubarak, O. Omer
{"title":"Modified gate activation functions of Bi-LSTM-based SC-FDMA channel equalization","authors":"Mohamed Mohamed, Hassan A. Hassan, M. Essai, Hamada Esmaiel, Ahmed S. A. Mubarak, O. Omer","doi":"10.2478/jee-2023-0032","DOIUrl":"https://doi.org/10.2478/jee-2023-0032","url":null,"abstract":"Abstract In recent years, artificial neural networks (ANNs) have grown a lot and helped solve numerous problems in wireless communication systems. We have evaluated the performance of the Bidirectional-Long-Short-Term-Memory (Bi-LSTM) recurrent neural networks (RNNs) for joint blind channel equalization and symbol detection using a variety of activation functions (Afs) for the gate units (sigmoid) of Bi-LSTMs without requiring any prior knowledge of channel state information (CSI). The performance of Bi-LSTM networks with different AFs found in the literature is compared. This comparison was carried out with the assistance of three different learning algorithms, namely Adam, rmsprop, and SGdm. The research findings clearly show that performance, as measured by equalization accuracy, can be improved. Furthermore, demonstrate that the sigmoid gate activation function (GAF), which is commonly used in Bi-LSTMs, does not significantly contribute to optimal network behavior. In contrast, there are a great many less well-known AFs that are capable of outperforming the ones that are most frequently utilized.","PeriodicalId":15661,"journal":{"name":"Journal of Electrical Engineering-elektrotechnicky Casopis","volume":"74 1","pages":"256 - 266"},"PeriodicalIF":0.8,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44550218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Harmonic reduction of grid-connected multilevel inverters using modulation of variable frequency carriers 基于变频载波调制的并网多电平逆变器谐波抑制
IF 0.8 4区 工程技术
Journal of Electrical Engineering-elektrotechnicky Casopis Pub Date : 2023-08-01 DOI: 10.2478/jee-2023-0033
Quang-Tho Tran
{"title":"Harmonic reduction of grid-connected multilevel inverters using modulation of variable frequency carriers","authors":"Quang-Tho Tran","doi":"10.2478/jee-2023-0033","DOIUrl":"https://doi.org/10.2478/jee-2023-0033","url":null,"abstract":"Abstract Multilevel three-phase inverters are increasingly popular due to their ability to generate high-quality output voltage with harmonic distortion lower than traditional inverters. They are used in various applications, including grid-connected renewable energy systems, motor drives, and power transmission systems, to improve efficiency and reduce costs. The control quality of grid-connected multilevel inverters depends on various factors such as the modulation technique, switching frequency, and control strategy. A good control system can achieve a balance between output current harmonics and switching losses, improving the efficiency and performance of the inverter. This paper suggests a technique for reducing current harmonics of grid-connected multilevel three-phase inverters using variable frequency carriers, without any corresponding increase of the number of switching commutations. The effectiveness of the suggested method has been confirmed through simulation results, which were compared to those obtained from the method of phase opposite disposition modulation using fixed frequency carriers.","PeriodicalId":15661,"journal":{"name":"Journal of Electrical Engineering-elektrotechnicky Casopis","volume":"74 1","pages":"267 - 276"},"PeriodicalIF":0.8,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49115300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Compact dual-mode loop resonators for microwave triplexer applications 用于微波三工器应用的紧凑型双模环路谐振器
IF 0.8 4区 工程技术
Journal of Electrical Engineering-elektrotechnicky Casopis Pub Date : 2023-08-01 DOI: 10.2478/jee-2023-0034
Jia‐lin Li, Peng Liu, Junchen Ye
{"title":"Compact dual-mode loop resonators for microwave triplexer applications","authors":"Jia‐lin Li, Peng Liu, Junchen Ye","doi":"10.2478/jee-2023-0034","DOIUrl":"https://doi.org/10.2478/jee-2023-0034","url":null,"abstract":"Abstract In this paper, we study meandered topologies of a dual-mode loop resonator for microwave multiplexer applications. Compact channel filter structures that characterize controllable transmission zeros locating simultaneously at the lower stopband or upper stopband are, for the first time, investigated for such a kind of resonators and based on this, a microstrip triplexer is proposed. The studied triplexer uses one of the filter structures to realize the middle channel, and the rest structure to realize the upper and lower channels. The center frequencies of the three channels are 1.8 GHz, 2.0 GHz and 2.2 GHz, and the 3-dB fractional bandwidths are 3.6%, 3.6% and 4.1%, respectively. The developed triplexer features high channel-isolations of over 40 dB as a result of the controllable transmission zeros of the channel filters.","PeriodicalId":15661,"journal":{"name":"Journal of Electrical Engineering-elektrotechnicky Casopis","volume":"74 1","pages":"277 - 281"},"PeriodicalIF":0.8,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45499082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Simulation of electrical system protection against the effects of a magnetic storm 电气系统抵御磁暴影响的模拟
IF 0.8 4区 工程技术
Journal of Electrical Engineering-elektrotechnicky Casopis Pub Date : 2023-08-01 DOI: 10.2478/jee-2023-0039
M. Stork, D. Mayer
{"title":"Simulation of electrical system protection against the effects of a magnetic storm","authors":"M. Stork, D. Mayer","doi":"10.2478/jee-2023-0039","DOIUrl":"https://doi.org/10.2478/jee-2023-0039","url":null,"abstract":"Abstract In the introduction of the presented work, the physical nature of the collapse of electrical energy transmission systems due to the influence of a magnetic storm is recalled. A mechanism is described by which, due to the non-linearity of the magnetic circuit of the system’s power transformers, quasi-direct currents are induced into the high-voltage part of the system, which cause thermal overload of these transformers. The article then suggests one of the possible ways to prevent these accidents. On the single-phase and then on the three-phase model, it is shown how these currents can be compensated. Using laboratory models, the compensation process was simulated and verified by measurements.","PeriodicalId":15661,"journal":{"name":"Journal of Electrical Engineering-elektrotechnicky Casopis","volume":"74 1","pages":"321 - 327"},"PeriodicalIF":0.8,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45795550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Design of RF energy harvester for 700 MHz 700MHz射频能量采集器的设计
IF 0.8 4区 工程技术
Journal of Electrical Engineering-elektrotechnicky Casopis Pub Date : 2023-08-01 DOI: 10.2478/jee-2023-0037
Ebha Deepti Singh, Abhay Chaturvedi
{"title":"Design of RF energy harvester for 700 MHz","authors":"Ebha Deepti Singh, Abhay Chaturvedi","doi":"10.2478/jee-2023-0037","DOIUrl":"https://doi.org/10.2478/jee-2023-0037","url":null,"abstract":"Abstract Radio frequency energy harvester is the conversion of ambient radio frequency electromagnetic waves into usable electrical energy, powering low-power devices without traditional power sources. In this paper, a novel RF energy harvester is proposed for 700 MHz frequency band. For the purpose of rectification, a Greinacher voltage rectifier cum multiplier is used in the circuit and Schottky Diode HSMS-2852 is used for implementing a rectifier. The LC impedance matching is implemented to improve the circuit performance of the harvester including conversion efficiency and output voltage. Simulation of the rectifier is done using the PathWave Advanced Design System (ADS) software. The rectifier shows the optimized performance at 5 kΩ load impedance. Simulation results show the highest efficiency of 33.1 % and an output voltage of 3.2 V with 8 dBm RF power at 700 MHz input frequency.","PeriodicalId":15661,"journal":{"name":"Journal of Electrical Engineering-elektrotechnicky Casopis","volume":"74 1","pages":"302 - 310"},"PeriodicalIF":0.8,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42579643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Inhomogeneous HfO2 layer growth at atomic layer deposition 原子层沉积时HfO2层的非均匀生长
IF 0.8 4区 工程技术
Journal of Electrical Engineering-elektrotechnicky Casopis Pub Date : 2023-08-01 DOI: 10.2478/jee-2023-0031
A. Kasikov, A. Tarre, G. Vinuesa
{"title":"Inhomogeneous HfO2 layer growth at atomic layer deposition","authors":"A. Kasikov, A. Tarre, G. Vinuesa","doi":"10.2478/jee-2023-0031","DOIUrl":"https://doi.org/10.2478/jee-2023-0031","url":null,"abstract":"Abstract Thin HfO2 films atomic layer deposited from hafnium alkyl amide and oxygen plasma were analysed using spectroscopic ellipsometry and X-ray reflectivity. Low refractive index of the material for samples with less than 30 nm thickness marks the index inhomogeneity at the first stage of growth. The transition from rising density to a more stable growth takes place at about 10 to 25 nm film thickness. HfO2 films used for resistive switching experiments demonstrate either clockwise or counterclockwise behaviour depending on the film thickness. The reason for this may be the disruption of the conductive filament at different metal-insulator interfaces, which could be favoured by several mechanisms.","PeriodicalId":15661,"journal":{"name":"Journal of Electrical Engineering-elektrotechnicky Casopis","volume":"74 1","pages":"246 - 255"},"PeriodicalIF":0.8,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49111128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Conformable fractional-order derivative based adaptive FitzHugh-Nagumo neuron model 基于符合分数阶导数的自适应FitzHugh-Nagumo神经元模型
IF 0.8 4区 工程技术
Journal of Electrical Engineering-elektrotechnicky Casopis Pub Date : 2023-08-01 DOI: 10.2478/jee-2023-0035
E. Karakulak
{"title":"Conformable fractional-order derivative based adaptive FitzHugh-Nagumo neuron model","authors":"E. Karakulak","doi":"10.2478/jee-2023-0035","DOIUrl":"https://doi.org/10.2478/jee-2023-0035","url":null,"abstract":"Abstract Various neuron models have been proposed and are extensively examined in the scientific literature. The FitzHugh-Nagumo neuron model is one of the most well-known and studied models. The FitzHugh-Nagumo model is not biologically consistent but operationally simple. A fractional-order derivative is described as a derivative with a non-integer order. Caputo, Grünwald-Letnikov, and Riemann-Liouville are some of the well-known fractional order derivatives. However, a simple fractional-order derivative called the conformable fractional-order derivative has been proposed in the literature and it is much simpler to use. In literature, there are already neuron models with fractional-order derivatives. In this study, a FitzHugh-Nagumo model circuit with a conformable fractional derivative capacitor and conformable fractional derivative inductor is proposed. The proposed circuit is modelled, and its simulation results are given. The simulation results reveal that the model circuit shows both slow and fast adaptation in firing frequency under sustained current stimulation.","PeriodicalId":15661,"journal":{"name":"Journal of Electrical Engineering-elektrotechnicky Casopis","volume":"74 1","pages":"282 - 292"},"PeriodicalIF":0.8,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45731152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Throughput performance optimization of NOMA-assisted cooperative relay system with realistic impairments 具有实际损伤的NOMA辅助协同中继系统的吞吐量性能优化
IF 0.8 4区 工程技术
Journal of Electrical Engineering-elektrotechnicky Casopis Pub Date : 2023-08-01 DOI: 10.2478/jee-2023-0038
P. Bachan, Aasheesh Shukla, A. Bansal
{"title":"Throughput performance optimization of NOMA-assisted cooperative relay system with realistic impairments","authors":"P. Bachan, Aasheesh Shukla, A. Bansal","doi":"10.2478/jee-2023-0038","DOIUrl":"https://doi.org/10.2478/jee-2023-0038","url":null,"abstract":"Abstract This work aims to investigate the outage and throughput performance of non-orthogonal multiple access assisted cooperative relay system (CRS-NOMA) considering the realistic impairments caused due to in-phase and quadrature-phase imbalance (IQI), channel estimation errors (CEE), and successive interference cancellation (SIC) errors. More specifically, we investigate a model in which two-phase downlink transmission is carried out in two different modes: (i) CRS-NOMA without direct links and (ii) CRS-NOMA with direct links (CRS-DLNOMA). In CRS-NOMA mode, the source broadcasts a composite NOMA signal to destination users with the assistance of a decode-and-forward (DF) relay. In contrast, in CRS-DLNOMA, direct and cooperative links are available for transmission. We derive the analytical expressions of outage probability and throughput for both the NOMA destinations to evaluate the system performance of both CRS-NOMA and CRS-DLNOMA modes of transmission. Furthermore, numerical simulations also study and validate the influence of IQI, CEE, and SIC errors on the outage and throughput performance. The simulation results verify that realistic impairments degrade the system performance, but the presence of direct link has a positive impact on outage and throughput. Additionally, we use the golden search method to optimize the power allocation factor (PAF) and transmission rate to maximize the throughput at the near user while ensuring the throughput constraint at the far user.","PeriodicalId":15661,"journal":{"name":"Journal of Electrical Engineering-elektrotechnicky Casopis","volume":"74 1","pages":"311 - 320"},"PeriodicalIF":0.8,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41372470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A miniaturized quintuple-band frequency selective surface based on enclosed cross slots 一种基于封闭交叉槽的小型化五频带频率选择面
IF 0.8 4区 工程技术
Journal of Electrical Engineering-elektrotechnicky Casopis Pub Date : 2023-08-01 DOI: 10.2478/jee-2023-0036
P. Prasad, Akhilesh Kumar
{"title":"A miniaturized quintuple-band frequency selective surface based on enclosed cross slots","authors":"P. Prasad, Akhilesh Kumar","doi":"10.2478/jee-2023-0036","DOIUrl":"https://doi.org/10.2478/jee-2023-0036","url":null,"abstract":"Abstract This article presents a low-profile quintuple-band frequency selective surface (FSS) that is designed as a sub-reflector for applications including satellite systems (C band), EPR (electron paramagnetic resonance) spectrometers, motion and traffic light crossing detectors (X band), Direct Broadcast Satellite and broadcasting satellite service (Ku band), and shortrange applications (K band). The dimensions of the miniaturized unit cell 0.08λ0×0.08λ0×0.012λ0, where, λ0 is the free-space wavelength corresponding to the lower cut-off frequency. There are five stop bands, and frequencies at which they resonate are 6.3, 7.06, 9.30, 11.2, 14.0, and 18.64 GHz. The fractional bandwidths (FBW) of these bands are 62.6, 7.5, 9.2, 11, and 11.69%, respectively. Additionally, as a result of the structure’s four-fold symmetry, it exhibits a good polarization-insensitive response as well as a stable response in both the TE and TM modes. Full-wave simulation is performed on the structure, after which an equivalent circuit model is constructed.","PeriodicalId":15661,"journal":{"name":"Journal of Electrical Engineering-elektrotechnicky Casopis","volume":"74 1","pages":"293 - 301"},"PeriodicalIF":0.8,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44686108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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