Hasil untuk "Electrical engineering. Electronics. Nuclear engineering"

Z. Galazka

β-Ga2O3 is an emerging, ultra-wide bandgap (energy gap of 4.85 eV) transparent semiconducting oxide, which attracted recently much scientific and technological attention. Unique properties of that compound combined with its advanced development in growth and characterization place β-Ga2O3 in the frontline of future applications in electronics (Schottky barrier diodes, field-effect transistors), optoelectronics (solar- and visible-blind photodetectors, flame detectors, light emitting diodes), and sensing systems (gas sensors, nuclear radiation detectors). A capability of growing large bulk single crystals directly from the melt and epi-layers by a diversity of epitaxial techniques, as well as explored material properties and underlying physics, define a solid background for a device fabrication, which, indeed, has been boosted in recent years. This required, however, enormous efforts in different areas of science and technology that constitutes a chain linking together engineering, metrology and theory. The present review includes material preparation (bulk crystals, epi-layers, surfaces), an exploration of optical, electrical, thermal and mechanical properties, as well as device design/fabrication with resulted functionality suitable for different fields of applications. The review summarizes all of these aspects of β-Ga2O3 at the research level that spans from the material preparation through characterization to final devices.

H. Bilgili, Elif Kucuktag

Sleep apnea is a sleep disorder that significantly affects human life and occurs as a result of repeated obstructions in the respiratory system lasting at least 10 seconds during sleep. The most common type, Obstructive Sleep Apnea (OSA), affects the upper respiratory tract, whereas Central Sleep Apnea (CSA) occurs due to dysfunction in the respiratory control center in the brain. Sleep apnea manifests with symptoms such as fatigue upon awakening, snoring, and daytime sleepiness. If left untreated, it may lead to serious health complications including stroke, cardiovascular diseases, and hypertension. Polysomnography (PSG) is the most widely used diagnostic method for sleep apnea. However, this test involves several limitations in terms of time consumption, patient comfort, and financial cost. Therefore, there is an increasing need for alternative engineering-based diagnostic support methods to complement polysomnography. Recent advancements in Biomedical Engineering, Electrical and Electronics Engineering, and Software Engineering have enabled the development of portable, cost-effective, and highly compatible systems for sleep apnea detection. Sleep apnea can be identified through the processing of physiological signals such as electroencephalography (EEG), electrocardiography (ECG), electrooculography (EOG), and oxygen saturation levels. The acquired data are analyzed using artificial intelligence techniques and machine learning algorithms, which have become prominent tools in biomedical signal analysis. Furthermore, the integration of wearable devices and Internet of Things (IoT)-based technologies allows continuous monitoring of patients in home environments. This study discusses the significance of engineering-based solutions in sleep apnea diagnosis and highlights their contributions to modern healthcare technologies.

G. Bramerdorfer, J. Tapia, J. Pyrhönen et al.

Disruptive innovations in electrical machine design optimization are observed in this paper, motivated by emerging trends. Improvements in mathematics and computer science enable more detailed optimization scenarios that cover evermore aspects of physics. In the past, electrical machine design was equivalent to investigating the electromagnetic performance. Nowadays, thermal, rotor dynamics, power electronics, and control aspects are included. The material and engineering science have introduced new dimensions on the optimization process and impact of manufacturing, and unavoidable tolerances should be considered. Consequently, multifaceted scenarios are analyzed and improvements in numerous fields take effect. This paper is a reference for both academics and practicing engineers regarding recent developments and future trends. It comprises the definition of optimization scenarios regarding geometry specification and goal setting. Moreover, a materials-based perspective and techniques for solving optimization problems are included. Finally, a collection of examples from the literature is presented and two particular scenarios are illustrated in detail.

Shihao Zhang, Yanhui Xiao, Huawei Tian et al.

Abstract Unlike single-image steganography, the scheme of payload distribution on different images plays a pivotal role in the security performance of multi-image steganography. In this paper, a novel multi-image steganography scheme: image stitching sender (ISS) is proposed, which achieves optimal payload distribution by optimizing the stitching scheme of multi-cover-images. In the ISS scheme, we employ peak signal-to-noise ratio as the similarity evaluation metric for the stitched cover image and stego image. Besides, genetic algorithm is used to find the local optimal solution for the similarity, corresponding to a locally optimal multi-image steganographic stitching scheme. The experiment demonstrates that ISS exhibits enhanced anti-detection capabilities in comparison to other multi-image steganography schemes. Furthermore, when combined with non-additive embedding methods, the ISS can achieve a more substantial improvement in security compared to additive embedding methods.

Mingxin Zhang, Xue Wang, Jing Sun et al.

The emerging wearable skin-like electronics require the ultra-flexible organic transistor to operate at low voltage for electrical safety and energy efficiency and simultaneously enable high field-effect mobility to ensure the carrier migration ability and the switching speed of circuits. However, the currently reported low-voltage organic transistors generally present low mobility, originating from the trade-off between molecular polarity and surface polarity of the dielectrics. In this work, the orientation polarization of the dielectric is enhanced by introducing a flexible quaternary ammonium side chain, and the surface polarity is weakened by the shielding effect of the nonpolar methyl groups on the polar nitrogen atom. The resulting antisolvent QPSU dielectric enables the high-dielectric constant up to 18.8 and the low surface polarity with the polar component of surface energy only at 2.09 mJ/m2. Such a synergistic polarization engineering between orientation polarization and surface polarity makes the solution-processed ultraflexible transistors present the ultralow operational voltage down to −3 V, the ultrahigh charge-carrier mobility up to 8.28 cm2 V−1 s−1 at 1 Hz, excellent cyclic operational stability and long-term air stability. These results combined with the ultrathin thickness of transistor as low as 135 nm, the ultralight mass of 0.5 g/m2, the conformal adherence capability on human skin and 1-μm blade edge, and the strong mechanical robustness with stable electrical properties for 30,000 bending cycles, open up an available strategy to successfully realize low-voltage high-mobility solution-processed organic transistor, and presents the potential application of QPSU dielectric for the next-generation wearable imperceptible skin-like electronics.

Akansha Kumari, Rakesh K. Singh, Abhay Kr. Aman et al.

The electrical, electronics,and drug industries are heavily reliant on the use of Silica materials for several applications. Green source of production of silica materials is very important to meet the growing demandfor industrial purposes. The present work discusses the recent nanosilica production using low-costmethods, from rice husk-agricultural waste, andtheir structural, microstructural, and optical properties measurement for its applications.The crystallite size of silica particleswas measured using XRD is 26 nm and 55 nm, which are prepared from rice husk synthesized by both coprecipitation and leaching processes, respectively.. The SEM images of both the samples showed structural order of the pores within the mesoporous structure. The leached sample showed a purity of around 80%. The infrared spectral data also supports the presence of hydrogen-bonded silanol groups and the siloxane groups in the silica. These nanosilica particles showed Photoluminescence in UV, Visible, and NIR regions. The nanoscale silica formation is also confirmed by TEM and DLS measurements. Zeta Potential studies found -22.12 mV reveals the stability of prepared nano silica for a longer duration.

Lorenzo Bonetti, Daniele Natali, Stefano Pandini et al.

This paper introduces a novel approach to 4D printing tailored structures with reversible two-way shape-memory effect (SME) through material extrusion technology. To this aim, methacrylated poly(ε-caprolactone) (PCL) was synthesized and evaluated from a rheological perspective to determine its suitability for extrusion-based printing. Following a printability assessment, an optimal set of parameters was identified to fabricate 3D structures, UV-crosslinked during printing. Subsequently, a physical and thermo-mechanical characterization of the printed structures was conducted to deepen the understanding of the fabrication process and properties of the obtained structures. To assess the shape-memory properties of the printed structures, both the one-way and two-way SME under load were investigated. Overall, this study opens the floodgates to implementing 4D printing via material extrusion technology, specifically targeting PCL-based semi-crystalline chemically crosslinked polymer networks with two-way SME. Because of its cost-effectiveness, versatility, and user-friendly nature, extrusion-based printing offers noteworthy advantages over other additive manufacturing approaches when reversible behavior of the printed structures is needed. Lastly, a glimpse of potential 4D printed structures from PCL-based semi-crystalline chemically crosslinked polymer networks is presented. The approach described holds significant promise across multiple research and industrial domains, including but not limited to smart actuators, soft robotics, and medical devices.

M.I. Sayyed, Abdelmoneim Saleh, Anjan Kumar et al.

Investigations were conducted on the addition of barium's impact on the radiation shielding and physical attributes of five different glasses, designated S1–S5, with varying BaO contents. Using two point sources namely Co60 and Cs137 along with a scintillation detector [NaI(TL)], experimental measurements were made of the shielding parameters of γ-rays, namely the effective atomic number (Zeff), electron density (Nel), half-value layer (HVL), linear attenuation coefficient (μ), mass attenuation coefficient (μm), mean free path (λ), and radiation protection effectiveness at the energies of 0.664, 1.177, and 1.334 MeV, and comparisons made with recently considered glasses as well as frequently employed materials for γ-ray shielding. The results show that the examined glasses' physical and radiation shielding qualities are improved by the addition of BaO. The μ values increased from 0.245 to 0.275 cm−1 (0.662 MeV), from 0.174 to 0.198 cm−1 (1.173 MeV), and from 0.161 to 0.189 (1.332 MeV). The observed values of HVL decreased from 2.83, 3.98, and 4.3 cm to 2.5, 3.5, and 3.62 cm at 0.662, 1.173, and 1.332 MeV, respectively, for the samples S1 and S5. In addition, the S5 glass sample was determined to have the best protection against photon among all the samples that were evaluated, as well as against recently considered glasses and those materials often utilized for gamma-ray shielding purposes.

D. Khvalin

With the help of analysis of cooling type influence on the probability of turbogenerators unfailing operation for different power shown that a design complication and the use of new auxiliary systems for the cooling intensification with increasing power unit leads to the decrease in generators reliability. The main ways to ensure generators reliability are considered: implementation of systems and methods of control and diagnostics of main component parts, the reserve of important machinery systems as well as the simplification of generators design with simultaneous non-use a number of auxiliary systems. The advantages for application of full air cooling in comparison with hydrogen and hydrogen-water cooling are shown and also the need of refusal to use hydrogen cooling for powerful turbogenerators of nuclear power plants units is scientifically substantiated. On the base of analysis for domestic and world experience of design and operation of a power electrical machines with full air cooling shown that modern level of engineering and technologies allows building high-power turbogenerators with full air cooling for ensuring a fire and explosion safety of thermoelectric and nuclear power plants. In this case, it is necessary to reconsider the economic efficiency criterions towards the increase in reliability and the decrease in maintenance price.

Tianyu Cang, Chenyi Liu, H. Tao

This study represents a pioneering exploration into the emerging intersection of power electronics and laser detection technologies, a field that holds tremendous promise for revolutionizing a wide range of applications from renewable energy to autonomous vehicles, by leveraging their unique synergies to drive unprecedented advancements in efficiency and precision. It begins with an exploration of the individual advancements in both fields, emphasizing the strides made in efficiency enhancements, control mechanisms, and range improvements. The discussion then transitions to the integration of these technologies, showcasing their combined system efficiencies and applications in contexts such as renewable energy systems, LIDAR in autonomous vehicles, and industrial laser cutting. Notable advancements, such as the use of advanced semiconductor materials and innovative control strategies, are examined. The paper also addresses the challenges faced by these technologies, including environmental susceptibility and complexity, while proposing future prospects. The conclusion synthesizes these insights, underscoring the pivotal role of this technological convergence in shaping the future of electrical engineering and photonics.

H. Takei

ABSTRACT In a proton linear accelerator (linac), the proton beam is sometimes unexpectedly interrupted because of the electrical discharge caused by radio frequency, device/equipment failure, and other factors. Are these beam trips random? Traditionally, beam trips have been implicitly assumed to occur randomly. In this study, we investigated whether beam trips occur randomly in the Japan Proton Accelerator Research Complex (J-PARC) linac. The aim was to estimate the beam trip frequency in a superconducting proton linac for an accelerator-driven nuclear transmutation system. First, the J-PARC linac was classified into five subsystems. Then, the reliability function for the operation time in each subsystem was obtained by the Kaplan – Meier estimation, a reliability engineering method. This reliability function was used to investigate the randomness of beam trips. Analysis of operational data for five subsystems of the J-PARC linac for five years showed that beam trips occurred randomly in some subsystems. However, the beam trips did not occur randomly in many subsystems of the proton linac, including the ion source and the acceleration cavity, which are the primary subsystems of the proton linac.

Francisco Cejas Rodríguez, Elizabeth Roig Villariño, Dayniel Hernández Mestre et al.

A partir de la información extraída de la Base de datos de fanerógamas (plantas con flores) de Cuba, depositada en el Instituto de geografía Tropical, la presente investigación conformó una tabla en Excel que recoge la información sistemática detallada en cuanto a: familia botánica, género, especie, autor de la especie y sinonimia, entre otros, junto al nombre común, cuyo empleo facilita el reconocimiento de la especie a nivel del público en general. Con diferentes Macros implementadas sobre Visual Basic for Applications (VBA), que automatizaron la revisión del entorno, se procedió a un análisis de la información compilada. Se obtuvo una  aproximación al estado de conocimiento sobre la composición y distribución de las especies arbóreas en las formaciones boscosas naturales cubanas, señalándose las principales dificultades para acometer esta tarea y recomendaciones para llevarla a término felizmente.

Georg Winkens, Alexander Kauffmann, Johannes Herrmann et al.

Abstract Mo-Ti alloys form solid solutions over a wide range of compositions, with lattice misfit parameters increasing significantly with titanium content. This indicates a strong increase in the critical stress for edge dislocation motion. Here, we probe the transition from screw to edge dislocation-dominated strengthening in Mo-Ti solid solutions with titanium content up to 80 at%. The alloys were scale-bridging characterized to isolate the impact of substitutional solid solution strengthening. Mechanical testing yielded no significant influence of grain boundaries or grain orientation. The results were corrected for the strengthening by unavoidable interstitial oxygen. Modelling of screw and edge dislocation-controlled solid solution strengthening was applied to the results to evaluate the contributions of both dislocation types. The analysis reveals that screw dislocation motion controls the strength in allows with less than 40 at% titanium, while edge dislocation motion provides comparable strength for 60–80 at% titanium. These results in a system of reduced chemical complexity support the recent investigations of edge dislocation-controlled strengthening found in high-entropy alloys.

Robert T. Woodward, Alexander Bismarck

editorial

P. Antony Seba, J. V. Bibal Benifa

This article performs a detailed data scrutiny on a chronic kidney disease (CKD) dataset to select efficient instances and relevant features. Data relevancy is investigated using feature extraction, hybrid outlier detection, and handling of missing values. Data instances that do not influence the target are removed using data envelopment analysis to enable reduction of rows. Column reduction is achieved by ranking the attributes through feature selection methodologies, namely, extra-trees classifier, recursive feature elimination, chi-squared test, analysis of variance, and mutual information. These methodologies are ranked via Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) using weight optimization to identify the optimal features for model building from the CKD dataset to facilitate better prediction while diagnosing the severity of the disease. An efficient hybrid ensemble and novel similarity-based classifiers are built using the pruned dataset, and the results are thereafter compared with random forest, AdaBoost, naive Bayes, k-nearest neighbors, and support vector machines. The hybrid ensemble classifier yields a better prediction accuracy of 98.31% for the features selected by extra tree classifier (ETC), which is ranked as the best by TOPSIS.

Dr. Elena Petrova

Graphene, a two-dimensional carbon nanomaterial with exceptional mechanical, electrical, and optical properties, has emerged as a transformative material in the domain of flexible and transparent electronics. Its high carrier mobility, mechanical flexibility, and optical transmittance make it ideal for next-generation devices such as flexible displays, wearable sensors, transparent electrodes, and bendable photovoltaic cells. This article explores recent advancements in the synthesis, integration, and performance of graphene-based electronic components, while highlighting the current challenges related to scalability, uniformity, and interface engineering. Finally, the paper discusses future directions toward large-scale production and hybrid material systems for industrial application.

Daniel Martín, J. Bocio-Núñez, S. F. Scagliusi et al.

Background Electrical stimulation is a novel tool to promote the differentiation and proliferation of precursor cells. In this work we have studied the effects of direct current (DC) electrical stimulation on neuroblastoma (N2a) and osteoblast (MC3T3) cell lines as a model for nervous and bone tissue regeneration, respectively. We have developed the electronics and encapsulation of a proposed stimulation system and designed a setup and protocol to stimulate cell cultures. Methods Cell cultures were subjected to several assays to assess the effects of electrical stimulation on them. N2a cells were analyzed using microscope images and an inmunofluorescence assay, differentiated cells were counted and neurites were measured. MC3T3 cells were subjected to an AlamarBlue assay for viability, ALP activity was measured, and a real time PCR was carried out. Results Our results show that electrically stimulated cells had more tendency to differentiate in both cell lines when compared to non-stimulated cultures, paired with a promotion of neurite growth and polarization in N2a cells and an increase in proliferation in MC3T3 cell line. Conclusions These results prove the effectiveness of electrical stimulation as a tool for tissue engineering and regenerative medicine, both for neural and bone injuries. Bone progenitor cells submitted to electrical stimulation have a higher tendency to differentiate and proliferate, filling the gaps present in injuries. On the other hand, neuronal progenitor cells differentiate, and their neurites can be polarized to follow the electric field applied.

Maninder Singh, Shankar Singh

G. Buticchi, C. Lam, Ruan Xinbo et al.

Renewable Energy Systems have been in the spotlight of the academic and industrial research for more than two decades, thanks to the development of several fields related to the Electrical Engineering. More recently, with the increasing complexity of the individual renewable energy systems and the interconnection to the grid, the scientific panorama has been witnessing to a convergence of different topics, which span across several IEEE-IES thematic areas: power electronics, electrical machines, smart grids, energy storage, transportation electrification and aerospace. After a brief overview of the renewable energy technologies, this work deals with how the convergence of multiple technologies developed to provide marginal support to the grid has evolved into the foundation of the future utility grid and expanded to transportation sector. It will be shown how the design of a renewable energy system cannot prescind anymore from the electrical grid and from the ancillary services that are requested. Example of convergence are given for a smart transformer application and for a transportation application.