bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Whole-Body Vibration and Manually Assisted Locomotor Therapy on Neurotrophin-3 Expression and Microglia/Macrophage Mobilization Following Thoracic Spinal Cord Injury in Rats
Authors: Schaufler Diana , Manthou Maria Eleni , Theotokis Paschalis , Rink-Notzon Svenja , Angelov Doychin N.
Published: April 2023

Microglial cells play an important role in neuroinflammation and secondary damages after spinal cord injury (SCI). Progressive microglia/macrophage inflammation along the entire spinal axis follows SCI, and various factors may determine the microglial activation profile. Neurotrophin-3 (NT-3) is known to control the survival of neurons, the function of synapses, and the release of neurotransmitters, while also stimulating axon plasticity and growth. We examined the effects of whole-body vibration (WBV) and forms of assisted locomotor therapy, such as passive flexion–extension (PFE) therapy, at the neuronal level after SCI, with a focus on changes in NT-3 expression and on microglia/macrophage reaction, as they play a major role in the reconstitution of CNS integrity after injury and they may critically account for the observed structural and functional benefits of physical therapy. More specifically, the WBV therapy resulted in the best overall functional recovery when initiated at day 14, while inducing a decrease in Iba1 and the highest increase in NT-3. Therefore, the WBV therapy at the 14th day appeared to be superior to the PFE therapy in terms of recovery. Functional deficits and subsequent rehabilitation depend heavily upon the inflammatory processes occurring caudally to the injury site; thus, we propose that increased expression of NT-3, especially in the dorsal horn, could potentially be the mediator of this favorable outcome.
A Comparative Study on the Carcass and Meat Chemical Composition, and Lipid-Metabolism-Related Gene Expression in Korean Hanwoo and Brindle Chikso Cattle
Authors: Hoa Van-Ba , Song Dong-Heon , Seol Kuk-Hwan , Kang Sun-Moon , Kim Hyun-Wook , Bae In-Seon , Kim Eun-Sung , Park Yeon-Soo , Cho Soo-Hyun
Published: April 2023

The objective of this study was to elucidate the effect of cattle breed on carcass and meat chemical composition, fatty acid profiles, and lipid-metabolism-related genes. For this study, same-age Hanwoo and Chikso steers (n = 6 per breed) reared under identical conditions were used. Immediately after slaughter, muscle tissues were collected for analysis of mRNA expression. At 24 h post-mortem, the carcasses were assessed for carcass traits (marbling score, meat yield, etc.), and meat quality and fatty acid profiles in the longissimus lumborum (LL) and semimembranosus (SM) muscles. The results showed that no differences in the slaughter weight, dressing rate, back-fat thickness, trimmed fat, and total meat yield occurred between the two breeds (p > 0.05). However, Hanwoo cattle had a higher marbling score, intramuscular fat (IMF) content, and expression level of lipid-metabolism-related genes such as lipoprotein lipase, peroxisome proliferator-activated receptor gamma, and fatty acid binding protein 4, compared with Chikso (p < 0.05). Contrastingly, Chikso had a higher total unsaturated fatty acid content and expression level of stearoyl CoA desaturase 1 (p < 0.05). It may be said that the difference in the expression levels of lipid-metabolism-related genes could be the molecular factors underlying IMF deposition and fatty acid profile differences in the beef from the two breeds.
Particle-in-Cell Simulations for the Improvement of the Target Erosion Uniformity by the Permanent Magnet Configuration of DC Magnetron Sputtering Systems
Authors: Jo Young Hyun , Cheon Cheongbin , Park Heesung , Lee Hae June
Published: April 2023

Improving the target erosion uniformity in a commercial direct current (DC) magnetron sputtering system is a crucial issue in terms of process management as well as enhancing the properties of the deposited film. Especially, nonuniform target erosion was reported when the magnetic flux density gradient existed. A two-dimensional (2D) and a three-dimensional (3D) parallelized particle-in-cell (PIC) simulation were performed to investigate relationships between magnetic fields and the target erosion profile. The 2D PIC simulation presents the correlation between the heating mechanism and the spatial density profiles under various magnet conditions. In addition, the 3D PIC simulation shows the different plasma characteristics depending on the azimuthal asymmetry of the magnets and the mechanism of the mutual competition of the E × B drift and the grad-B drift for the change in the electron density uniformity.
Modification of the Bellman–Ford Algorithm for Finding the Optimal Route in Multilayer Network Structures
Authors: Timofeeva Olga , Sannikov Alexey , Stepanenko Maria , Balashova Tatiana
Published: April 2023

One of the actual tasks of the contemporary logistics business using the “just in time” supply planning concept, is to distribute manufactured goods among the objects of the distribution network in the most efficient manner at the lowest possible cost. The article is devoted to the problem of finding the optimal path in network structures. The problem statement for multilayer data transmission networks (MDTN), which is one of the possible representations of multimodal transport networks, is considered. Thus, each MDTN layer can be represented as a separate type of transport. The problem is solved by modifying the Bellman–Ford mathematical programming algorithm. Load testing of the modified method was performed, and a comparative analysis was given, including an assessment of speed and performance, proving the effectiveness of the results of the study. Based on the results of comparative analysis, recommendations for using a modified version of the Bellman–Ford algorithm for application in practical problems in optimizing logistics networks are proposed. The results obtained can be used in practice not only in logistics networks but also in the construction of smart energy networks, as well as in other subject areas that require optimization of multilayer graph structures.
Robust Stabilization of a Microgrid with Communication Delay and Uncertainties
Authors: Khalil Ashraf , Alfergani Asma , Shaltami Farhat M. , Asheibi Ali
Published: April 2023

In this paper, the robust stabilization for the networked microgrid system is presented. A microgrid implements master-slave control architecture where the communication channel is utilized to exchange the reference current signals. With this structure, a time delay exists in the reference control signal which may lead to instability. The analysis of the control strategy is carried out in dq reference frame. The microgrid is constituted by PV and wind energy sources supplying a load through voltage source inverters. The stochastic nature of renewable energy sources introduces uncertainties which can be represented as fluctuations in the voltage and the current. The main contribution of the paper is formulating the controller design of the microgrid with communication delay and uncertainties in the model as H∞ control problem and Lyapunov–Krasovskii functional is utilized to develop stability criterion in bilinear matrix inequality form. Grey wolf optimizer is used to minimize the performance index and derive the stabilizing controller. The microgrid performance is tested through simulation using the time-varying nonlinear model of the microgrid. The results prove that satisfactory current and power-sharing are attained even with the existence of time delays and uncertainties.
A Comparative Study of Safety Zone Visualisations for Virtual and Physical Robot Arms Using Augmented Reality
Authors: Cogurcu Yunus Emre , Douthwaite James A. , Maddock Steve
Published: April 2023

The use of robot arms in various industrial settings has changed the way tasks are completed. However, safety concerns for both humans and robots in these collaborative environments remain a critical challenge. Traditional approaches to visualising safety zones, including physical barriers and warning signs, may not always be effective in dynamic environments or where multiple robots and humans are working simultaneously. Mixed reality technologies offer dynamic and intuitive visualisations of safety zones in real time, with the potential to overcome these limitations. In this study, we compare the effectiveness of safety zone visualisations in virtual and real robot arm environments using the Microsoft HoloLens 2. We tested our system with a collaborative pick-and-place application that mimics a real manufacturing scenario in an industrial robot cell. We investigated the impact of safety zone shape, size, and appearance in this application. Visualisations that used virtual cage bars were found to be the most preferred safety zone configuration for a real robot arm. However, the results for this aspect were mixed for a virtual robot arm experiment. These results raise the question of whether or not safety visualisations can initially be tested in a virtual scenario and the results transferred to a real robot arm scenario, which has implications for the testing of trust and safety in human–robot collaboration environments.
Synthesis of Bimetallic Nanoparticles and Applications—An Updated Review
Authors: Idris Dahir Sagir , Roy Arpita
Published: April 2023

The manipulation of matter at the atomic level (nanotechnology) has experienced an explosion in research interest in recent years. Bimetallic nanoparticles are vital due to their high biocompatibility, stability and comparatively less toxicity. The synthesis methods that include physical, chemical and biological methods are explored and explained in detail, along with their advantages. They have a wide range of applications due to their synergistic properties including biological applications (in medicine and agriculture), environmental application (in water treatment and removal of toxic contaminants), engineering application (in nanosensors, nanochips and nano-semiconductors) and chemical and physical application (in optics, catalysis and paints). The green synthesis approach is a promising method of synthesis that can give rise to more biocompatible and less toxic bimetallic nanoparticles due to increasing environmental pollution. However, despite these interesting attributes of bimetallic nanoparticle, there is still much work to be done to improve the biocompatibility of bimetallic nanoparticles because of their toxicity and potentially hazardous effects.
Morphology Evolution of Mg2SiO4 Particles Synthesized by Spray Pyrolysis from Precursor Solution
Authors: Animut Temesgen Yiber , Ningsih Henni Setia , Yeh Wen-Ling , Shih Shao-Ju
Published: April 2023

Forsterite (Mg2SiO4) materials have been used in the industrial applications of refractory materials, bone grafting materials, and microwave dielectric materials. In order to avoid the formation of the secondary phase of MgO or MgSiO3, spray pyrolysis with the precursors of magnesium nitrate hydrate and tetraethyl orthosilicate has been applied to synthesized Mg2SiO4 powders. In this study, three typical morphologies of smooth solid sphere, rough hollow sphere, and concaved hollow sphere were observed using scanning electron microscopy and transmission electron microscopy. The experimental results suggested that morphology and particle size distribution are strongly influenced by the calcination temperature. Finally, the corresponding powder formation mechanisms were proposed and discussed.
Structural Characterization of Pharmaceutical Cocrystals with the Use of Laboratory X-ray Powder Diffraction Patterns
Authors: Chernyshev Vladimir V.
Published: April 2023

X-ray powder diffraction is a vital analytical tool that is used in pharmaceutical science. It is increasingly used to establish the crystal structure of a new pharmaceutical substance, in particular, cocrystal or its polymorphic forms. This review begins with a brief discussion of the reliability of the structural parameters retrieved from powder patterns. Recent examples of the successful determination of crystal structures of pharmaceutical cocrystals and salts from powder diffraction data are discussed. These examples show the increased capabilities of laboratory X-ray powder diffractometers and modern software in solving actual problems of pharmaceutical science.
A Fast Recovery SiC TED MOS MOSFET with Schottky Barrier Diode (SBD)
Authors: Cheng Hongyu , Li Wenmao , Wang Peiran , Chen Jianguo , Wang Qing , Yu Hongyu
Published: April 2023

Achieving low conduction loss and good channel mobility is crucial for SiC MOSFETs. However, basic planar SiC MOSFETs provide challenges due to their high density of interface traps and significant gate-to-drain capacitance. In order to enhance the reverse recovery property of the device, a Schottky barrier diode (SBD) was added to the source contact area, the top of the current spreading region, of a trench-etched double-diffused SiC MOS (TED MOS). Two types of SBD structures were optimized to improve the electrical properties using 3D simulation software, “TCAD Silvaco”. During reverse recovery simulation, the carriers of the device were withdrawn from the SBD, indicating that the new design was effective. It also showed that the recovery properties of the new design depended on temperature, carrier lifetime, and the work functions of metals. All the new designs were evaluated in various circumstances to determine the trend. Ultimately, in high-speed switching circuits, the SiC TED MOS with SBD structure efficiently boosted switching speed, while reducing switching loss.
Nuclear and Cytoplasmic hTERT, Tumor-Infiltrating Lymphocytes, and Telomere Elongation Leukocytes Are Independent Factors in the Response to Neoadjuvant Treatment in HER2-Enriched Breast Cancer
Authors: Delmonico Lucas , Bines José , Nascimento Cristina Moreira do , Fernandes Priscila Valverde , Barbosa Isabel de Souza , Ribeiro Gabriel Brito , de Paula Bruno Henrique Rala , Silvestre Rafaele Tavares , Ornellas Maria Helena Faria , Alves Gilda , Lage Claudia
Published: April 2023

HER2-enriched tumors are responsible for 20% of breast tumors and have high rates of immune infiltrates in the tumor stroma that respond favorably to neoadjuvant chemotherapy. In the context of tumors, telomeres control cell death and prevent tumor cells from replicating discontinuously, leading to their immortalization. This study aimed to evaluate the presence of tumor-infiltrating lymphocytes, hTERT expression, hTERT promoter mutation, and leukocyte telomere length in HER2-enriched breast tumors. A total of 103 cases were evaluated, 19 with pathologic complete response. The TILs percentage was above ≥10 in 44 cases (43%) and significantly present in patients ≥50 years of age. hTERT staining positivity was mostly nuclear, significantly present in the non-pCR group, and associated with a lower survival rate. Leukocyte telomeres were elongated for HER2-enriched tumors, and in multivariate analysis, shortening was associated with an increased risk of death. Overall, our results show that the nuclear and cytoplasmic presence of hTERT may indicate a worse prognosis and that leukocyte telomere elongation is a protective factor.
Whole Genome Resequencing Reveals Genetic Diversity and Selection Signatures of Ethiopian Indigenous Cattle Adapted to Local Environments
Authors: Terefe Endashaw , Belay Gurja , Tijjani Abdulfatai , Han Jianlin , Hanotte Olivier
Published: April 2023

Cattle are among the most important domesticated bovid species in the world, of which Ethiopia possesses large populations adapted to different agro-ecologies and production systems. Though several molecular population genetic studies have been done on Ethiopian indigenous cattle, genomic diversity and selection signatures pertinent to adaptation to the different local environments have yet to be comprehensively characterized. Here, the whole genome sequences of 151 samples from 14 Ethiopian indigenous cattle populations were analyzed to assess genomic diversity and differentiation as well as signatures of positive selection (using Hp, iHS, FST, and XP-CLR) in comparison to Sudanese zebu, Asian zebu, Ankole, and African and European taurine cattle. High genomic differentiation was observed between Ethiopian and non-Ethiopian cattle populations, while low genomic differentiation and inbreeding were present between and within Ethiopian cattle populations. Sixteen genome regions overlapping with 40 candidate genes were commonly identified by at least three genome scan methods. High frequencies of missense SNPs in ITPR2, CHADL, GNAS, STING1, and KIT genes with high haplotype differentiations were observed in Ethiopian cattle compared to non-Ethiopian cattle. The candidate genes were significantly associated with several biological functions and molecular pathways responsible for nutrient metabolism, skeletal development, immune response, reproduction, water balance, coat color pigmentation, and circulatory homeostasis. Our results provide new insights into the adaptation of the Ethiopian indigenous cattle to the country’s diverse environments.
FRET Based Biosensor: Principle Applications Recent Advances and Challenges
Authors: Verma Awadhesh Kumar , Noumani Ashab , Yadav Amit K. , Solanki Pratima R.
Published: April 2023

Förster resonance energy transfer (FRET)-based biosensors are being fabricated for specific detection of biomolecules or changes in the microenvironment. FRET is a non-radiative transfer of energy from an excited donor fluorophore molecule to a nearby acceptor fluorophore molecule. In a FRET-based biosensor, the donor and acceptor molecules are typically fluorescent proteins or fluorescent nanomaterials such as quantum dots (QDs) or small molecules that are engineered to be in close proximity to each other. When the biomolecule of interest is present, it can cause a change in the distance between the donor and acceptor, leading to a change in the efficiency of FRET and a corresponding change in the fluorescence intensity of the acceptor. This change in fluorescence can be used to detect and quantify the biomolecule of interest. FRET-based biosensors have a wide range of applications, including in the fields of biochemistry, cell biology, and drug discovery. This review article provides a substantial approach on the FRET-based biosensor, principle, applications such as point-of-need diagnosis, wearable, single molecular FRET (smFRET), hard water, ions, pH, tissue-based sensors, immunosensors, and aptasensor. Recent advances such as artificial intelligence (AI) and Internet of Things (IoT) are used for this type of sensor and challenges.
Retinal Nerve Fiber Layer Imaging with Two Different Spectral Domain Optical Coherence Tomographs: Normative Data for Romanian Children
Authors: Nemeș-Drăgan Iulia-Andrada , Drăgan Ana-Maria , Hapca Mădălina Claudia , Oaida Mara
Published: April 2023

The purpose of this study is to analyze and compare pediatric normative data for the retinal nerve fiber layer of Romanian children using two different spectral domain optical coherence tomographs. Due to different scanning speeds and axial and transverse resolution, the results of the measurements of scans cannot be transposed. A total of 140 healthy children aged 4 to 18 were enrolled in the study. Overall, 140 eyes were scanned with a Spectralis SD-OCT (Heidelberg Technology), and the other 140 eyes were imaged with a Copernicus REVO SOCT (Optopol Technology (Zawiercie, Poland)). The mean global RNFL thickness and average RNFL thickness for the four quadrants were measured and compared. The average peripapillary RNFL thickness measured with the Spectralis was 104.03 ± 11.42 (range 81 to 126 µm), while the one measured with the Revo 80 was 127.05 ± 15.6 (range 111.43–158.28). The RNFL thickness measurements taken with the Spectralis in the superior, inferior, nasal, and temporal quadrants were 132 ±19.1, 133.5 ± 21.77, 74 ± 16.48, and 73 ± 11.95 µm, respectively, while those taken with the Revo 80 were 144.44 ± 9.25, 144.86 ±23.12, 96.49 ± 19.41, and 77 ± 11.4 µm, respectively. Multivariate analysis showed that the average RNFL thickness was not influenced by gender or eye laterality and was negatively correlated with age when we used the Spectralis device. This study provides normative data for SD-OCT peripapillary RNFL in healthy Romanian children for two different tomographs. These data help the clinician evaluate and interpret the results of optical coherence tomography for a child, taking into consideration all the technical and individual parameters.
Dephasing Dynamics in a Non-Equilibrium Fluctuating Environment
Authors: Meng Xiangjia , Sun Yaxin , Wang Qinglong , Ren Jing , Cai Xiangji , Czerwinski Artur
Published: April 2023

We performed a theoretical study of the dephasing dynamics of a quantum two-state system under the influences of a non-equilibrium fluctuating environment. The effect of the environmental non-equilibrium fluctuations on the quantum system is described by a generalized random telegraph noise (RTN) process, of which the statistical properties are both non-stationary and non-Markovian. Due to the time-homogeneous property in the master equations for the multi-time probability distribution, the decoherence factor induced by the generalized RTN with a modulatable-type memory kernel can be exactly derived by means of a closed fourth-order differential equation with respect to time. In some special limit cases, the decoherence factor recovers to the expression of the previous ones. We analyzed in detail the environmental effect of memory modulation in the dynamical dephasing in four types of dynamics regimes. The results showed that the dynamical dephasing of the quantum system and the conversion between the Markovian and non-Markovian characters in the dephasing dynamics under the influence of the generalized RTN can be effectively modulated via the environmental memory kernel.
Perceptions about the Assessment in Emergency Virtual Education Due to COVID-19: A Study with University Students from Lima
Authors: Montes-Iturrizaga Iván , Zambrano Aranda Gloria María , Pamplona-Ciro Yajaira Licet , Villalba-Condori Klinge Orlando
Published: April 2023

The COVID-19 pandemic forced a large section of Peruvian universities to design systems for emergency virtual education. This required professors to quickly learn how to use teaching platforms, digital tools and a wide range of technological skills. In this context, it is remarkable that formative assessment may have been the pedagogical action with the greatest number of challenges, tensions and problems, due to the lack of preparation of many professors to apply performance tests and provide effective feedback. Given this, it is presumed that these insufficiencies (previously exhibited in face-to-face education) were transferred to virtual classrooms in the framework of the health emergency. A survey study was carried out on 240 students from a private university in Lima to find out their perceptions and preferences regarding the tests that their professors administered in the virtual classrooms. It was found that the students were assessed, for the most part, with multiple choice tests. In addition, it was found that the students recognized that the essay tests were the most important for their education, but they preferred multiple choice tests. Finally, it was found that law school students were mostly assessed with essay tests and psychology students with oral tests.
Medical Students’ Participation in Social Studying and Learning during COVID-19
Authors: Mead Benjamin J. , Estaphan Suzanne , Corrigan Gerry
Published: April 2023

COVID-19 transformed the medical school learning environment. How social studying and learning (SSL) may have changed was considered worthy of exploration. This study describes the effect of the learning environment transformation on how SSL is conducted by medical students and the reasoning behind any changes. A post-positivist stance was adopted with a mixed method convergent-parallel approach. An online survey explored the participation rate and nature of SSL and how these related to literature-identified underpinning factors that influence participation in SSL. A follow-up interview explored the survey responses. A total of 87 survey responses were collected. Following exclusion of incomplete responses, 57 responses were analysed, and nine follow-up interviews were conducted. Cross-tabulation and logistic regression were conducted to analyse the quantitative data and thematic analysis was conducted to analyse the qualitative data. No significant difference was observed in SSL participation rate during COVID-19. Students transitioned from in-person to Zoom meetings for sensibility, ease and convenience. Students continued participating in SSL for motivation and began participating for accountability, focus and replacement of lost social interaction. The same content was studied using a wider range of activities. Significant decreases were observed in students’ perception of the effect of a range of factors. The observed changes to SSL during online learning suggest that SSL is integral for many medical students and will be adapted as required. Given that medical school will always involve some periods of online learning, understanding of the nature of and driving factors behind how medical students engage in SSL during online learning may enable medical educators to support all aspects of student learning.
Trends and Opportunities in Enzyme Biosensors Coupled to Metal-Organic Frameworks (MOFs): An Advanced Bibliometric Analysis
Authors: Sales Misael Bessa , Neto José Gadelha Lima , De Sousa Braz Ana Kátia , De Sousa Junior Paulo Gonçalves , Melo Rafael Leandro Fernandes , Valério Roberta Bussons Rodrigues , Serpa Juliana de França , Da Silva Lima Ana Michele , De Lima Rita Karolinny Chaves , Guimarães Artemis Pessoa , de Souza Maria Cristiane Martins , Lopes Ada Amélia Sanders , Rios Maria Alexsandra de Sousa , Serafim Leonardo Farias , dos Santos José Cleiton Sousa
Published: April 2023

The unique properties of metal-organic frameworks (MOFs) such as their large surface area and high porosity have attracted considerable attention in recent decades. The MOFs are a promising class of materials for developing highly efficient biosensors due to these same properties. This bibliometric analysis focused on the use of MOFs as enzyme-coupled materials in biosensor construction and aimed to provide a comprehensive overview of the research field by analyzing a collected database. The analysis included identifying the countries that have published the most, the most prominent applications, and trends for future directions in the field. The study used three databases with different numbers of documents, differentiated by research areas, with refinements made to the search as needed. The results suggest that MOF-derived biosensors are a growing field, with the Republic of China emerging as a significant contributor to research in this area. The study also used computational processing of trend analysis and geocoding to reveal these findings.
Fault Detection and Zonal Protection Strategy of Multi-Voltage Level DC Grid Based on Fault Traveling Wave Characteristic Extraction
Authors: Han Yuqi , Ma Ruiguang , Li Ting , Zeng Wenhui , Liu Yangtao , Wang Yuhong , Guo Chunsheng , Liao Jianquan
Published: April 2023

Currently, DC breakers are commonly used in mainstream protection schemes for DC grids to eliminate faults. However, the cost of high voltage DC (HVDC) breakers is high, and equipping each DC line with DC breakers is expensive. In order to minimize the number of DC breakers while ensuring the reliability of the power supply, a zonal protection strategy suitable for multi-voltage level DC grids is proposed. Subsequently, the qualitative impact of partial power interruption caused by fault DC areas is analyzed in the system. The basic zonal principle of the multi-voltage level DC grid is formulated, taking into account unbalanced power, the mode of system-level control, and the type of converters. Additionally, a time sequence coordination strategy is derived in detail based on the characteristics of DC breakers, AC/DC converters, DC/DC converters, AC breakers, high-speed switches, and other fault removal components. Finally, a seven-terminal DC grid is modeled in the PSCAD/EMTDC simulation platform. According to the simulation analysis, the DC grid can adopt the converter with fault clearing ability or an AC circuit breaker to cooperate with the fast disconnector (FD) to complete fault clearing in the DC fault area under the proposed zonal protection coordination strategy.
Multisegmented Intelligent Solution for MT-HVDC Grid Protection
Authors: Yousaf Muhammad Zain , Mirsaeidi Sohrab , Khalid Saqib , Raza Ali , Zhichu Chen , Rehman Wasif Ur , Badshah Fazal
Published: April 2023

Fault detection continues to be a relevant and ongoing topic in multiterminal High Voltage Direct Current (MT-HVDC) grid protection. In MT-HVDC grids, however, high DC-fault currents result from a failure of a complex protective threshold in traditional protection schemes, making Voltage Source Converter (VSC) vulnerable to such potent transient currents. In this innovative single-ended DC protection scheme, multiple time window segments are used to consider the effects of the transient period across limiting inductors at each end of the link. Multiple segments of 0–0.8, 0.8–1.5, and 1.5–3.0 ms reduce relay failure and improve the sensitivity to high fault impedance while requiring minimal computational effort. It employs feature extraction tools such as Stationary Wavelet Transform and Random Search (RS)-based Artificial Neural Networks (ANNs) for detecting transmission line faults within DC networks. Its goal is to improve the accuracy and reliability of protective relays as a result of various fault events. Simulations showed that the proposed algorithms could effectively identify any input data segment and detect DC transmission faults up to 500 ohms. Accuracy for the first segment is 100% for fault impedance up to 200 ohms, whereas the second and third segments show 100% accuracy for high impedance faults up to 400 ohms. In addition, they maintain 100% stability even under external disturbances.
Optimization of Ohmic Contact to Ultrathin-Barrier AlGaN/GaN Heterostructure via an ‘Ohmic-Before-Passivation’ Process
Authors: Ji Yuan , Huang Sen , Jiang Qimeng , Zhang Ruizhe , Fan Jie , Yin Haibo , Zheng Yingkui , Wang Xinhua , Wei Ke , Liu Xinyu
Published: April 2023

Non-recessed ohmic contact resistance (Rc) on ultrathin-barrier (UTB) AlGaN(<6 nm)/GaN heterostructure was effectively reduced to a low value of 0.16 Ω·mm. The method called the ‘ohmic-before-passivation’ process was adopted to eliminate the effects of fluorine plasma etching, in which an alloyed Ti/Al/Ni/Au ohmic metal stack was formed prior to passivation. The recovery of 2-D Electron Gas (2DEG) adjacent to the ohmic contact was enhanced by composite double-layer dielectric with AlN/SiNx passivation. It is found that the separation between the recovered 2DEG and the ohmic contacting edge can be remarkably reduced, contributing to a reduced transfer length (LT) and low Rc, as compared to that of ohmic contact to the AlGaN(~20 nm)/GaN heterostructure with a pre-ohmic recess process. Thermionic field emission is verified to be the dominant ohmic contact mechanism by temperature-dependent current-voltage measurements. The low on-resistance of 3.9 Ω·mm and the maximum current density of 750 mA/mm with Vg = 3 V were achieved on the devices with the optimized ohmic contact. The non-recessed ohmic contact with the ‘ohmic-before-passivation’ process is a promising strategy to optimize the performance of low-voltage GaN-based power devices.
Model-Driven Developed Terminal for Remote Control of Charging Station for Electric Vehicles Powered by Renewable Energy
Authors: Vujasinović Jovan , Savić Goran , Prokin Milan
Published: April 2023

A terminal for remote control of charging stations for electric vehicles (EV) powered by renewable energy has been presented in this paper. This terminal enables remote control of EV chargers, smart batteries, smart electricity meters, fiscal cash registers (FCR), as well as remote control of renewable energy sources and other devices within the station. This terminal also makes charging stations more accessible to electric vehicles users, to electricity distribution companies, to electricity suppliers, to tax administrations, and finally to users and owners of charging stations. Therefore, communication and control with all these devices and systems is integrated in one device. Realization of hardware and software of such a terminal has also been described in this paper. The net result of development and commercialization of terminals would encourage an increase in the use of electric vehicles powered by energy from renewable sources, which would cause a decrease in the level of air pollution and all negative effects it causes in the future. Different categories of this device are considered. Moreover, although it is a device with embedded software, a very advanced method was used, that is, a model-driven development method, which enables fast and more efficient development and maintenance of the device. The results of the application of this method to the terminal for remote control of fiscal cash registers are provided. They were compared with the results of the development of the terminal for remote control of smart meters without applying this method. A simulation of the development of the terminal for remote control of the station is also provided. The presented method can be used in the future for faster and better-quality development of embedded software.
A Comprehensive Overview of the Temperature-Dependent Modeling of the High-Power GaN HEMT Technology Using mm-Wave Scattering Parameter Measurements
Authors: Crupi Giovanni , Latino Mariangela , Gugliandolo Giovanni , Marinković Zlatica , Cai Jialin , Bosi Gianni , Raffo Antonio , Fazio Enza , Donato Nicola
Published: April 2023

The gallium-nitride (GaN) high electron-mobility transistor (HEMT) technology has emerged as an attractive candidate for high-frequency, high-power, and high-temperature applications due to the unique physical characteristics of the GaN material. Over the years, much effort has been spent on measurement-based modeling since accurate models are essential for allowing the use of this advanced transistor technology at its best. The present analysis is focused on the modeling of the scattering (S-) parameter measurements for a 0.25 μm GaN HEMT on silicon carbide (SiC) substrate at extreme operating conditions: a large gate width (i.e., the transistor is based on an interdigitated layout consisting of ten fingers, each with a length of 150 μm, resulting in a total gate periphery of 1.5 mm), a high ambient temperature (i.e., from 35 °C up to 200 °C with a step of 55 °C), a high dissipated power (i.e., 5.1 W at 35 °C), and a high frequency in the millimeter-wave range (i.e., from 200 MHz up to 65 GHz with a step of 200 MHz). Three different modeling approaches are investigated: the equivalent-circuit model, artificial neural networks (ANNs), and gated recurrent units (GRUs). As is shown, each modeling approach has its pros and cons that need to be considered, depending on the target performance and their specifications. This implies that an appropriate selection of the transistor modeling approach should be based on discerning and prioritizing the key features that are indeed the most important for a given application.
Strong Interference UAV Motion Target Tracking Based on Target Consistency Algorithm
Authors: Tan Li , Huang Xiaokai , Lv Xinyue , Jiang Xujie , Liu He
Published: April 2023

In recent years, unmanned aerial vehicle (UAV) image target tracking technology, which obtains motion parameters of moving targets and achieves a behavioral understanding of moving targets by identifying, detecting and tracking moving targets in UAV images, has been widely used in urban safety fields such as accident rescue, traffic monitoring and personnel detection. Due to the problems of complex backgrounds, small scale and a high density of targets, as well as mutual occlusion among targets in UAV images, this leads to inaccurate results of single object tracking (SOT). To solve the problem of tracking target loss caused by inaccurate tracking results, this paper proposes a strong interference motion target tracking method based on the target consistency algorithm for SOT based on an interframe fusion and trajectory confidence mechanism, fusing previous frames for the tracking trajectory correction of current frames, learning again from previous frames to update the model and adjusting the tracking trajectory according to the tracking duration. The experimental results can show that the accuracy of the proposed method in this paper is improved by 6.3% and the accuracy is improved by 2.6% compared with the benchmark method, which is more suitable for applications in the case of background clutter, camera motion and viewpoint change.
Three-Dimensional Lattice Structure to Reduce Parasitic Inductance for WBG Power Semiconductor-Based Converters
Authors: Min Sung-Soo , Eom Chan-Hyeok , Jang Yeong-Seop , Kim Rae-Young
Published: April 2023

Wide bandgap (WBG) power semiconductors can achieve high efficiency and power density due to their low on-resistance and fast switching speeds. However, the fast-switching speed induces voltage to the parasitic inductance in the circuit, causing a significant overshoot in the drain-source voltage of the devices and the ringing of the drain current due to resonance with the parasitic capacitance. Thus, minimizing parasitic inductance is necessary for driving WBG power semiconductors in a stable manner. This paper proposes a three-dimensional lattice structure that reduces parasitic inductance through horizontal and vertical magnetic flux cancellations within a printed circuit board (PCB). The relationship between the magnetic flux cancellation and the parasitic inductance is analyzed, and the magnetic flux cancellation in the proposed structure is described. In addition, a practical PCB layout design procedure based on the proposed structure is provided. Simulation results demonstrate a 55.8% reduction in parasitic inductance, and experimental results show reduced overshoot and ringing at the switching transient, resulting in a 26% reduction in switching loss. As a result, the proposed method can improve the efficiency and stability of WBG device-based power converters.
CAPNet: Context and Attribute Perception for Pedestrian Detection
Authors: Zhu Yueyan , Huang Hai , Yu Huayan , Chen Aoran , Zhao Guanliang
Published: April 2023

With a focus on practical applications in the real world, a number of challenges impede the progress of pedestrian detection. Scale variance, cluttered backgrounds and ambiguous pedestrian features are the main culprits of detection failures. According to existing studies, consistent feature fusion, semantic context mining and inherent pedestrian attributes seem to be feasible solutions. In this paper, to tackle the prevalent problems of pedestrian detection, we propose an anchor-free pedestrian detector, named context and attribute perception (CAPNet). In particular, we first generate features with consistent well-defined semantics and local details by introducing a feature extraction module with a multi-stage and parallel-stream structure. Then, a global feature mining and aggregation (GFMA) network is proposed to implicitly reconfigure, reassign and aggregate features so as to suppress irrelevant features in the background. At last, in order to bring more heuristic rules to the network, we improve the detection head with an attribute-guided multiple receptive field (AMRF) module, leveraging the pedestrian shape as an attribute to guide learning. Experimental results demonstrate that introducing the context and attribute perception greatly facilitates detection. As a result, CAPNet achieves new state-of-the-art performance on Caltech and CityPersons datasets.
Influence of Water on the Methane Adsorption Capacity of Organic-Rich Shales and Its Controlling Factors: A Review
Authors: Xing Yijie , Xiao Xianming , Zhou Qin , Liu Wei , Zhao Yanming
Published: April 2023

A typical feature of shale gas reservoirs is that they contain a significant amount of adsorbed gas. The evaluation and prediction of adsorbed gas play important roles in shale gas exploration and development. However, the presence of water in shale reservoirs makes this work more difficult. In recent years, research related to the occurrence and distribution of water in shales and its effect on methane adsorption have become a prominent issue. In this paper, the factors controlling water in shale nanopores and its influence on methane adsorption were systematically reviewed. It is revealed that the connate water content in shales and their water absorption capacity vary widely, and both are mainly related to the organic matter contents and properties and mineral compositions. The water absorption capacity of organic matter in shales is mainly affected by its nanopore content, structure and surface chemical properties (such as the type and amount of oxygen-containing functional groups), which are jointly constrained by its kerogen type and maturity. Even under moist conditions, the organic matter in shales still shows a strong methane adsorption capacity, although the water decreases the adsorption capacity to some extent. The hydrophilicity of different minerals in shales varies greatly, but the type and amount of clay minerals are the main factors affecting the adsorbed water content or water adsorption capacity of shales. The nanopore structure and characteristics of shales, such as the pore type, specific surface area, pore size distribution and heterogeneity, directly impact the occurrence and distribution of water. The competition for adsorption between water and methane at some adsorption sites is the main mechanism for the reduction in the methane adsorption capacity of moist shales. In addition, external environmental factors, such as pressure and temperature, can change the distribution and occurrence of water in shales and, thus, the influence of water on the methane adsorption capacity to a certain extent. This paper also discusses some current issues regarding the effect of water on methane adsorption capacity and highlights future research directions in this field.
Heat Recovery Using PCM in Decentralised Façade Ventilation
Authors: Galiszewska Beata , Zender-Świercz Ewa
Published: April 2023

A study of heat recovery in a façade ventilation unit was carried out under laboratory conditions using a climate chamber that allowed stable outdoor and indoor conditions to be simulated. The unit, equipped with a reversible fan and a chamber for the heat exchanger, controlled by an automation control system, was designed to exchange air in the room by alternating supply and exhaust cycles of specific durations. Three types of heat exchangers were tested, which were filled with different phase change materials, in order to estimate the efficiency of the façade ventilation unit in terms of its heat recovery capability. The efficiency of the unit was determined based on the temperature efficiency of heat recovery for 144 setting combinations. The best efficiency results between 73.56% and 76.29% were obtained with a solution using a heat exchanger consisting of cylinders with an external diameter of 10 mm and a wall thickness of 1 mm filled with jojoba oil in a one minute cycle. The tests confirmed that the heat exchangers, which are part of the façade ventilation unit, fulfil their function and allow heat recovery from the exhaust air to pre-heat the supplied air. The study complements the existing scientific knowledge on the efficiency of heat exchangers filled with phase change material, operating in winter conditions with work cycles up to 5 min.
Agrivoltaic: A Strategic Assessment Using SWOT and TOWS Matrix
Authors: Maity Rittick , Sudhakar Kumarasamy , Abdul Razak Amir , Karthick Alagar , Barbulescu Dan
Published: April 2023

New strategies and market segments considering integrated approaches have emerged as critical components in the energy transition. Agrivoltaics is one approach that has shown a lot of promise for offering advantages in the food-energy-water nexus. The agrivoltaic system involves the installation of photovoltaic panels above agricultural lands to generate electricity while also allowing for crop production. The paper “SWOT and TOWS Matrix Analysis of Agrivoltaic System” comprehensively analyses the potential strengths, weaknesses, opportunities, and threats (SWOT) associated with implementing an agrivoltaic system. This study utilizes a SWOT analysis framework to identify and evaluate the internal and external factors that could impact the implementation and success of the agrivoltaic system. A TOWS matrix analysis is also conducted to formulate strategic recommendations based on the identified SWOT factors. The analysis results reveal that the agrivoltaic system has numerous strengths, including its potential to generate renewable energy, increase crop yield, and provide economic benefits to farmers. However, the system also faces several weaknesses and threats, such as high initial investment costs, land use conflicts, and potential environmental impacts. Based on the TOWS matrix analysis, this study provides strategic recommendations to maximize the potential of the agrivoltaic system while mitigating its weaknesses and threats. These recommendations include adopting a flexible pricing strategy, researching the system’s environmental impact, promoting collaboration between various stakeholders like government agencies, farmers, and energy service companies. Overall, this study provides valuable insights into the potential of agrivoltaic systems and the factors that should be considered when implementing such a system. The findings can help stakeholders make informed decisions and take appropriate actions to ensure the integration of agrivoltaic systems into agricultural practices.
District Heating System Optimisation: A Three-Phase Thermo-Hydraulic Linear Model
Authors: Pałka Piotr , Malec Marcin , Kaszyński Przemysław , Kamiński Jacek , Saługa Piotr
Published: April 2023

Investments in the development of the district heating system require a thorough analysis of the technical, economic, and legal aspects. Regarding the technical and economic context, a mathematical model of the district heating system has been proposed. It optimizes both the technical and economic aspects of the function and development of a district heating system. To deal with non-linearities, the developed linear programming model is divided into three phases: flow, thermal, and pressure. Therein, non-linear dependencies are calculated between the linear optimization phases. This paper presents the main assumptions and equations that were used to calculate the parameters of the heating system, along with the optimal level of heat production, the flow rate of the heating medium in the heat nodes and edges of the network graph, the heat, power, and temperature losses at each edge, and the purchase costs of heat and its transmission. The operation of the model was tested on a real-world district heating system. The case study results confirm that the model is effective and can be used in decision support. The economic results of the model, before the calibration process, were 3.6% different from historical values. After the calibration process, they were very similar to the real data—all percentage deviations were within 1%.