bluuebunny/crossref_metadata_2025 huggingface dataset:
Diffusion‐based conditional wind power forecasting via channel attention
Authors: Peng Hongqiao , Sun Hui , Luo Shuxin , Zuo Zhengmin , Zhang Shixu , Wang Zhixian , Wang Yi
Published: August 2023

Wind energy is one of the most significant renewable sources of energy while accurate and reliable wind power forecasting methods may greatly benefit power system planning and scheduling. Recently, many machine learning algorithms have shown significant advantages in how to extract temporal features for wind power forecasting. However, wind power curves in the time domain frequently display intermittent features and significant uncertainty, which is not favorable to precise and reliable forecasting. In this paper, the Diffusion and Channel Attention‐based Wind Power Forecasting (DC‐WPF) framework is proposed, which transforms wind power data into the frequency domain while applying advanced channel attention techniques to aid the model in capturing the frequency domain information and ultimately enhancing accuracy. With high‐accuracy results, DC‐WPF then proposes a diffusion‐based framework to transform the point forecasting results into probabilistic forecasts to capture the uncertainty. Finally, extensive experiments on six wind power plants show that our method can improve the point forecasting accuracy of wind power and provide advanced probabilistic forecasts at a multi‐time scale.
A fast radio burst with submillisecond quasi-periodic structure
Authors: Pastor-Marazuela Inés , van Leeuwen Joeri , Bilous Anna , Connor Liam , Maan Yogesh , Oostrum Leon , Petroff Emily , Straal Samayra , Vohl Dany , Adams Elizabeth A. K. , Adebahr Björn , Attema Jisk , Boersma Oliver M. , van den Brink R. , van Cappellen W. A. , Coolen Arthur H. W. M. , Damstra Sieds , Dénes Helga , Hess Kelley M. , van der Hulst J. M. , Hut Boudewijn , Kutkin Alexander , Marcel Loose G. , Lucero Danielle M. , Mika Ágnes , Moss Vanessa A. , Mulder Henk , Norden Menno J. , Oosterloo Tom A. , Rajwade Kaustubh , van der Schuur Daniel , Sclocco Alessio , Smits R. , Ziemke Jacob
Published: August 2023

Fast radio bursts (FRBs) are extragalactic radio transients of extraordinary luminosity. Studying the diverse temporal and spectral behaviour recently observed in a number of FRBs may help to determine the nature of the entire class. For example, a fast spinning or highly magnetised neutron star (NS) might generate the rotation-powered acceleration required to explain the bright emission. Periodic, subsecond components suggesting such rotation were recently reported in one FRB, and may also exist in two more. Here we report the discovery of FRB 20201020A with Apertif, an FRB that shows five components regularly spaced by 0.411 ms. This submillisecond structure in FRB 20201020A carries important clues about the progenitor of this FRB specifically, and potentially about the progenitors of FRBs in general. We therefore contrast its features to what is seen in other FRBs and pulsars, and to the predictions of some FRB models. We present a timing analysis of the FRB 20201020A components carried out in order to determine the significance of the periodicity. We compare these against the timing properties of the previously reported CHIME FRBs with subsecond quasi-periodic components, and against two Apertif bursts from repeating FRB 20180916B, which show complex time-frequency structure. We find the periodicity of FRB 20201020A to be marginally significant at 2.4σ. Its repeating subcomponents cannot be explained as pulsar rotation because the required spin rate of over 2 kHz exceeds the limits set by typical NS equations of state and observations. The fast periodicity is also in conflict with a compact object merger scenario. However, these quasi-periodic components could be caused by equidistant emitting regions in the magnetosphere of a magnetar. The submillisecond spacing of the components in FRB 20201020A, the smallest observed so far in a one-off FRB, may rule out both a NS spin period and binary mergers as the direct source of quasi-periodic FRB structure.
Early surge detection in a mGT plant coupled with large volumes
Authors: Niccolini Marmont Du Haut Champ Carlo Alberto , Silvestri Paolo , Reggio Federico , Ferrari Mario Luigi , Massardo Aristide Fausto
Published: August 2023

The present work features post-processing methods applied to vibro-acoustic data acquired from a T100 micro gas turbine (mGT) plant coupled with different volume interposed plenums. Such experimental campaign was conducted by relying on a test bench developed at the University of Genoa for hybrid systems emulation. Nonetheless, the obtained results can be generalized to all advanced cycles in which a mGT is coupled with further external elements which cause an increase of plant overall volume size. Since in this case a 100 kW mGT was employed, the interposed vessel was placed between heat recovery system outlet and combustor inlet, such as in common cases relevant to small size plants.

Post-processing techniques carried out on acoustic and vibrational measurements can make available innovative diagnostic tools and predictive solutions by relying on appropriate instability indicators which are defined basing only on microphone and accelerometer experimental data.

The main results presented in this work are relevant to rotating stall and incipient surge proper identification. Such investigation has been performed to increase the knowledge about such dangerous compressor working conditions; indeed, energy systems characterized by significant interposed volumes coupled with centrifugal compressors feature issues relevant to structural damaging due to surge and rotating stall.
Energy Management System for Smart Grids: Tests in Cyber-Physical Mode
Authors: Ferrari Mario Luigi , Gini Lorenzo , Pascenti Matteo
Published: August 2023

The objective of this work regards the laboratory assessment of the energy management system (EMS) for a smart grid, to be applied to the Eigerøy island (Norway) inside the H2020 ROBINSON project. The smart grid is based on the integration of industrial needs (a steam boiler fueled by LNG) with renewable sources and waste recycling (internal production of syngas and biogas). The mentioned EMS, developed to minimize energy generation costs, includes an optimization tool and a Model Predictive Control (MPC) software for the calculation of the activation and the set-point values of the prime movers. Moreover, a special scheduling approach was proposed for the electrolyzers connected to a hydrogen storage pressure vessel. In this work the EMS was tested in cyber-physical mode in the Innovative Energy Systems (IES) laboratory of the University of Genoa. In details, the tests were performed coupling component models with real hardware (microturbine and solar panels) available in the laboratory. The obtained optimization performance was highlighted on the basis of a comparison with a standard management of the smart grid.
Humidification Towards Flashback Prevention in a Classical Micro Gas Turbine: Thermodynamic Performance Assessment
Authors: Pappa Alessio , De Paepe Ward
Published: August 2023

Combustion air humidification has proven to be effective to stabilize hydrogen combustion and to avoid flashback apparition in a typical micro Gas Turbine (mGT). However, both the fuel alteration and combustion air dilution will impact the cycle performance. A complete characterization of this thermodynamic impact is essential to ensure that the mGTs become cleaner, and fully flexible to fit with the expectation of future small-scale decentralized power production. Therefore, the objective of this work is twofold: the determination of the necessary dilution for combustion stabilization, depending on the type of fuel, as well as the impact assessment on the cycle performance. In this framework, a hybrid model of the Turbec T100 mGT combustor, combining a 0D Chemical Reactor Network and 1D Laminar flame calculations, is used to first assess the flashback limits. The laminar flame speed is evaluated to predetermine the necessary minimal water dilution of the combustion air to avoid flashback for several CH4/H2blends. Second, a thermodynamic analysis is performed to assess the impact of the flame stabilization measures on the cycle performance of the mGT using Aspen Plus. The 0D/1D simulation results show that the combustor of the Turbec T100 can operate with fuels containing up to 100% hydrogen. However, the thermodynamic analysis shows that the water dilution leads to a decreased electrical performance. Future work consists in the iterative coupling of both 0D/1D and the Aspen model to correctly predict the flashback limits, considering the altering operating conditions. To conclude, with this work, we provide a framework for future mGT operations with alternative fuels.
Development of a digital signal processing model using a frequency synthesizer and synthesis of quadrature conversion circuits
Authors: Jumaev Odil , Mahmudov Giyosjon , Shermurodova Malika , Abdujalilov Azimjon
Published: August 2023

An important issue of improving the quality of the functioning of measuring systems is the improvement of the conversion methods and the algorithmization of the processes for eliminating various noises and interferences that arise in the tasks of analog-to-digital information conversion.The article analyzes the algorithms for assessing the accuracy of digital signal processing (DSP) in a complex of issues due to the development of digital and digital-analog element base, as well as the development of methods and algorithms for processing and generating signals.
Thermodynamic assessment of gasification and pyrolysis of marine algae to produce hydrogen-containing gas
Authors: Tsvetkov Maxim , Zaichenko Andrey , Podlesniy Dmitry
Published: August 2023

The article gives a thermodynamic assessment of modes of gasification and pyrolysis of algae of gross formulation C1H1.66O1.4 with obtaining hydrogen gas. The authors investigate the modes of air gasification and pyrolysis of algae at pressures of 0.1 MPa and 1 MPa with varying the fuel excess ratio and temperatures. In the case of gasification at a pressure of 0.1 MPa the hydrogen and carbon monoxide concentration increases with an increase of the fuel excess ratio (φ) from 2 to 10 and at φ = 10 and T = 1000 K reaches 25.95 mole % and 27.84 mole %, respectively. An increase in temperature from 1000 K to 1300 K leads to a decrease in the amount of hydrogen and an increase in carbon monoxide in the gaseous products. An increase in the operating pressure from 0.1 to 1 MPa at a gasification temperature of 1000 K leads to the formation of a small amount of methane (~ up to 5 mole %), a decrease in the mole content of hydrogen and carbon monoxide in the final products, and also to the formation of coke (at φ≥7), which we can use as a target product. The caloric value of the gases produced is higher in the pyrolysis of algae than in its gasification. The pressure increase at 1300 K has almost no effect on the equilibrium composition of the products in the gaseous products.
Method for water disinfecting by a single spatial electromagnetic field
Authors: Khalikov Abdulhak
Published: August 2023

The paper presents the results of a comparative analysis without reagent methods of water disinfection by a pulsed electromagnetic field. An improved design of the device for control systems of a single spatial electromagnetic field is proposed. The aim of the work is to develop and study the disinfection of water by a single spatial electromagnetic field, which improves the energy performance of the device, improves the technique, economic and operational characteristics with wide possibilities for its practical application. The theory of a unified spatial field assumes the interaction of four fields: pulsed electromagnetic, pulsed electric, permanent magnetic and gravitational. The theory of a unified spatial field is substantiated, which allows considering the issues of effective disinfection, desalination and purification of water, as well as studying the influence of electric, magnetic fields and electromagnetic waves on physical, chemical and biological processes occurring in liquids. Based on the theory presented in the work, the following conclusions can be drawn: a single spatial field allows you to disinfect and purify water; pulsed electric and magnetic fields allow saturating water with oxygen ions; the spatial field allows you to remove heavy metals from the water. According to the results of the analysis of power impulse systems, the ways of developing the device of a single spatial field are determined.
Silica clay (opoka) as a promising raw material for unfired wall products by compression molding
Authors: Kurilova Svetlana , Naumov Aleksey , Gebru Berhane
Published: August 2023

The article is devoted to the actual problem of producing unburnt wall products of compression molding with improved and high efficiency in terms of thermal and engineering properties. The article notes the relevance, attractiveness, and wide use of unburnt pressed products in modern civil engineering. The raw material composition and production technology of unburnt wall products of compression molding are described. The traditionally used aggregates for unburnt wall products of compression molding are reviewed and their properties are analyzed. High average density and high thermal conductivity are noted in these products. The objective is to improve the thermal characteristics of these products while ensuring their strength properties. For this purpose, it is proposed to introduce a porous component of siliceous rock called opoka (silica clay) into the raw material composition of products as a mineral filler. Opoka collected from three different deposits was reviewed, its characteristics given, and the raw material analyzed. It is noted that the porosity and average density of opoka depend on its deposit. The effect of porosity and average density of opoka on the average density, compressive strength, and water absorption of unburnt wall products of compression molding based on opoka with different porosities from different deposits is described. The effect of the properties of opoka on the properties of unburnt wall products of compression molding is explained. It is confirmed that the use of opoka in the production of unburnt wall products reduces the average density of the products and improves their thermal and engineering properties. The appropriateness of manufacturing large-sized hollow wall blocks based on opoka is substantiated.
Econometric modeling of the calculation of gross domestic product with the expense method
Authors: Saukhanov Janibek , Mirzanov Berdak , Mardonov Aminjon , Rikhsimbaev Odiljon
Published: August 2023

The results of the correlation between the factors affecting the gross domestic product were calculated on the basis of the methodology of the national accounting system, a regression equation was identified, and short-term alternative forecasting issues were clarified using a statistical index of GDP growth in 1997-2019 of the Republic of Uzbekistan in this article.
Prerequisites for the development of the system of automatic comparison of video and audio tracks by the speaker’s articulation
Authors: Shakirzyanov Marsel , Gibadullin Ruslan , Nuriyev Marat
Published: August 2023

Deep learning and reinforcement learning technologies are opening up new possibilities for the automatic matching of video and audio data. This article explores the key steps in developing such a system, from matching phonemes and lip movements to selecting appropriate machine-learning models. It also discusses the importance of getting the reward function right, the balance between exploitation and exploitation, and the complexities of collecting training data. The article emphasizes the importance of using pre-trained models and transfer learning, and the importance of correctly evaluating and interpreting results to improve the system and achieve high-quality content. The article focuses on the need to develop effective mapping quality metrics and visualization methods to fully analyze system performance and identify possible areas for improvement.
Quantifying the Subjective Experience of Nasal Obstruction: A Review
Authors: Rossi Meyer Monica K. , Most Sam P.
Published: August 2023

Nasal obstruction is an exceedingly common problem and challenging to treat due to its multifactorial etiology. Therefore, measuring treatment outcomes of nasal obstruction can be equally complex yet vital to appropriately assessing symptom improvement or resolution. Both physiologic and anatomic assessments of the nasal airway exist in addition to validated patient-reported outcome measures (PROMs), which objectify subjective nasal obstruction and sinonasal symptoms. Correlation between objective and subjective treatment outcome measures is controversial with clinical guidelines favoring the use of PROMs for surgical treatment of nasal obstruction. In this review, the anatomic and physiologic measurements of the nasal airway and validated PROMs will be discussed, as well as the rationale for implementing PROMs into the rhinoplasty surgeon's practice.
Visible-Light-Mediated Oxidation of 1-Benzyl-3,4-dihydroisoquinolines with Dioxygen: A Switchable Synthesis of 1-Benzoylisoquinolines and 1-Benzoyl-3,4-dihydroisoquinolines
Authors: Wu Hongli , Gan Haifeng , Ma Peipei
Published: August 2023

A visible-light-mediated metal-free oxidation of 1-benzyl-3,4-dihydroisoquinolines (1-BnDHIQs) for the switchable preparation of a wide range of 1-benzoylisoquinolines (BzIQs) and 1-benzoyl-3,4-dihydroisoquinolines (BzDHIQs) is realized using dioxygen as the oxidant. This protocol provides a facile route for the efficient synthesis of isoquinoline alkaloids. Mechanistic investigations suggest that a radical pathway and an ionic pathway may exist simultaneously, with both pathways proceeding via a common key peroxide intermediate to give the oxidized products.
A mathematical model for the process of accumulation of scientific knowledge in the early modern period
Authors: Zamani Maryam , El-Hajj Hassan , Vogl Malte , Kantz Holger , Valleriani Matteo
Published: August 2023

In the present work, we model the diffusion of scientific knowledge embodied in the textbooks of the Sphaera corpus. This corpus consists of more than 350 different editions of textbooks used for teaching astronomy in European universities during the early modern period. Connections between the editions are based on mutual semantic knowledge and are arranged in a multiplex network of four layers, with each layer representing a different semantic relation. The modeling aims for a better understanding (and possible prediction) of the process of knowledge accumulation in the various editions. We consider semantic text-parts as knowledge units transferred between the editions, and show how these units spread using both an SI model and its modified version, the Bass model. Both models include a parameter representing the rate of transfer, which is interpreted as the mechanism underlying the process of knowledge accumulation; the Bass model has an extra parameter that represents the rate of external influence and stands out as the “resistance to adoption from” and “resistance to be influenced by” other knowledge systems. The modeling has helped us to chart the path and mechanisms of knowledge transformation in the early modern period. Networks are identified by adding further layers whose graphs express socioeconomic relationships and conditional sub-networks. The comparison between the model and these layers enables us to conclude that the accumulation of knowledge was highly dependent on the institutional embedding of scientific production because the diffusion of knowledge was mostly determined by the economic constraints of early modern printers and publishers. It further suggests that geographic proximity played a role—although secondary—in the diffusion of knowledge but only under the condition that the book producers involved were still living. The transformation of early modern scientific knowledge is, therefore, highly dependent on the institutional and economic contexts of the book producers.
Modification to a testing assembly to enable strain-life measurements in pressurized hydrogen gas
Authors: Bradley P. E. , Martin M. L. , Connolly M. J. , Amaro R. L. , Lauria D. S. , Slifka A. J.
Published: August 2023

Strain-controlled fully reversed fatigue testing, or strain-life testing, provides critical information on material lifetime and damage response. Strain-life data in hydrogen gas environments is missing in the literature and could provide valuable insights into hydrogen effects on the mechanical response of metals such as steel. We adapted existing hydrogen-gas-environment mechanical-testing equipment, which had been designed only for tensile loads, to accommodate the large compressive loads needed to perform strain-life testing. The considerations of these adaptations are discussed. Successful strain-life testing data were acquired from a 4130 pressure vessel steel.
A singular linear statistic for a perturbed LUE and the Hankel matrices
Authors: Wang Dan , Zhu Mengkun , Chen Yang
Published: August 2023

In this paper, we investigate the Hankel determinant generated by a singular Laguerre weight with two parameters. Using ladder operators adapted to monic orthogonal polynomials associated with the weight, we show that one of the auxiliary quantities is a solution to the Painlevé III′ equation and derive the discrete σ-forms of two logarithmic partial derivatives of the Hankel determinant. We approximate the second-order differential equation satisfied by the monic orthogonal polynomials with respect to the singular Laguerre weight with two parameters to the double confluent Heun equation, leveraging the scaling limit for two parameters and the dimension of the Hankel determinant. In addition, we establish the asymptotic behavior of the smallest eigenvalue of large Hankel matrices associated with the weight with two parameters, using the Coulomb fluid method and the Rayleigh quotient.
Water-in-oil emulsion drop-wall impact: Effect of viscosity and water particles on slip length over an oleophilic surface
Authors: Piskunov Maxim , Piskunova Chelsea
Published: August 2023

The study is focused on the numerical simulation of the boundary slip of a water-in-oil (W/O) emulsion along an oleophilic surface in a 2D axisymmetric formulation of the Navier–Stokes equations for an incompressible laminar flow. Drops of emulsions with a volume fraction of the dispersed phase of 0.04–0.34 collide with a smooth glass wall at initial velocities of 1.2–3.6 m/s; the motion of the interface between the liquid and gas phases is resolved by the level set method. The influence of the wall wettability by oily liquids is demonstrated by varying the static contact angle up to 0.5° and by considering the dynamic one as a function of the empirically measured contact line velocity of the liquid drop according to Tanner's law. Numerical simulation of emulsion drop spreading dynamics reveals that the boundary slip of a heterogeneous liquid along a smooth oleophilic wall is different from that of a homogeneous. The temporal changes in the average viscous stress allowed the illustration of the interrelated effects of emulsion viscosity and the presence of disperse phase particles on the boundary slip of a heterogeneous liquid and its motion in the viscous boundary layer. The analytical expression evaluating the slip length for an arbitrary W/O emulsion was derived using the effective properties of the liquid. In testing the expression, the values of the maximum spreading factor of drops of an arbitrary W/O emulsion predicted by numerical simulation correspond to those determined from experiments at a moderate error of 7.4%.
Metamaterial based on labyrinthine tubes loaded periodically and ultra-low phase velocity to the low-frequency energy control
Authors: Almeida G. N. , Vergara E. F. , Lenzi Arcanjo
Published: August 2023

Sound energy control at low frequencies (≤1000 Hz) is necessary and very important in acoustics, especially when considering scientific and technological aspects. In this work, a modular acoustic metamaterial composed of a main waveguide loaded with small quarter-wavelength tubes is presented. Theoretical, numerical, and experimental methods are used to describe the accumulation of sound absorption peaks below the structure's bandgap with the number of peaks proportional to the structure's periodicity. The origin of the bandgap is due to the loaded tubes in the main waveguide. Ultra-low phase velocity (c̃p=16 m/s) and critical coupling were obtained in the model, which allowed perfect sound absorption at 292 Hz with a structure reaching a ratio of λ/90. The experimental results in the impedance tube support the theoretical and numerical discussions and demonstrate a sound energy control of 89% and 84% at 686 and 422 Hz, respectively. Finally, this work contributes to advances in the field of control and manipulation of low-frequency sound energy through periodic structures.
Influence of the wettability dividing line on bubble growth and detachment behavior in a von Kármán swirling flow field
Authors: Qiao Shuai , Cai Chujiang , Pan Chong , Liu Yanpeng
Published: August 2023

The contact-angle (CA) hysteresis generated by the difference between the advancing and receding CAs of a droplet on an inclined surface generates an adhesion force that can hold the droplet on the surface. Similarly, the CA hysteresis generated by a wettability dividing line (WDL) between the superhydrophobic and superhydrophilic regions can improve the anti-shear stability of bubbles in water, with a maximum range of more than 150° for the difference between the advancing and receding CAs. Based on this mechanism, the influence of a WDL on the growth and detachment behavior of bubbles at different Reynolds numbers (Re) in a von Kármán swirling flow field was experimentally studied. The results show that the WDL significantly improves the anti-shear stability of bubbles when compared to uniform superhydrophobic and hydrophilic surfaces. Furthermore, the detachment volume and maximum contact width decrease with increasing Re, while the tilt angle and asymmetry ratio increase significantly. The fluctuation amplitudes of these parameters gradually increase with rising Re. Based on variations in these parameters, bubbles' growth behavior can be classified into three modes: stabilization, transition, and oscillation. Additionally, the constraint mechanism of a WDL on a bubble was analyzed based on variations in the CA hysteresis generated by the WDL and the maximum contact width. Finally, the detachment dynamics of bubbles in the three modes were analyzed based on a force–balance model.
Recent dissertations on L2 pronunciation
Authors: Levis John M. , Zawadzki Zoë
Published: August 2023

This editorial summarizes 40 recent dissertations (2018–2023) on L2 pronunciation topics. Although it was nearly impossible to pigeonhole dissertations into single sub-categories (e.g., pronunciation training studies often also address questions of intelligibility), we have organized them into six main topic areas: Teachers and Learners; Special Contexts; Prosody and Fluency; Technology; Pronunciation Training; and Intelligibility, Comprehensibility and Accentedness. The wide range of dissertations from around the world indicates a bright future for the field.
Implementation of Fall Armyworm Management Plan in Ghana
Authors: Williams Frances , Marwijk Anne van , Rware Harrison , Essegbey George , Besah Patrick , Duah Solomon , Hevi Walter , Karbo Naaminong , Quaye Wilhemina , Watiti James
Published: August 2023

Fall armyworm (FAW), an invasive pest, was confirmed in Ghana in 2016. As a result, a group of stakeholders developed a national FAW management plan. This case considers a review of the management plan conducted through outcome harvesting, a Sprockler (story-based) inquiry, and interviews with key informants.

The review found evidence of stakeholder collaboration, increased public awareness of FAW and management practices, and more coordinated research into low-risk management options. It also found that the formal taskforce structure, common goals and ownership, effective collaboration and communication, and a commitment to implementing the action plan by all actors were the key factors in the FAW response. Challenges included a slow initial response, inadequate funds, and limitations in the agricultural extension system. Key steps to ensure future preparedness include implementation of the National Invasive Species Strategy and Action Plan (NISSAP), establishment of a standing taskforce and emergency fund to address new pest outbreaks, improved monitoring and surveillance especially at borders and ports of entry, strengthened research capacity, especially in pest risk analyses, involvement of all stakeholders at central and local levels, and development of generic and specific emergency response guidelines for future outbreaks.

Information

© CAB International 2023
Long-term corrosion of abandoned offshore steel infrastructure
Authors: Melchers Robert E. , Tan Mike Y.
Published: August 2023

A common practice in the offshore oil and gas (O&G) industry is to leave abandoned decommissioned pipelines and other steel infrastructure on the seafloor. Decisions about long-term environmental and other impacts and about the possibility of recovery require estimates of the likely long-term rate of deterioration, including corrosion loss and pit depth. These are considered as functions of time and environmental conditions including seawater temperature, dissolved oxygen concentration, salinity, seawater velocity, water pollution, microbiological activity, water depth, calcareous deposition and the effect of burial, all interpreted using established physico-chemical behaviour relevant for long-term exposures. Data for exposures up to some 600 years in seawaters are reviewed. Remaining research gaps and future perspectives of marine corrosion control are briefly discussed. Specific attention is given, by way of an example, to the influence on long-term durability of protective coatings and remnant cathodic protection, both areas in which further research is required.
Generation and optimization of cross-sections for electron-C4F7N collisions
Authors: Flynn M , Agan J , Neuber A , Stephens J
Published: August 2023

A complete and consistent set of electron-neutral collision cross-sections for the novel insulating gas C4F7N is reported. The set is composed of a combination of cross-sections previously reported in literature, optimized via a genetic algorithm in conjunction with a multi-term Boltzmann equation solver, and calculated ab initio using the R-matrix code Quantemol-EC. The finalized set accurately reproduces reported macroscopic rate and transport coefficients as well as Townsend coefficients and critical electric field strengths in C4F7N and its mixtures with nitrogen, carbon dioxide, and argon.
Long-term stability of molecular doped epigraphene quantum Hall standards: single elements and large arrays (R
K/236 ≈ 109 Ω)
Authors: Shetty Naveen , Bergsten Tobias , Eklund Gunnar , Avila Samuel Lara , Kubatkin Sergey , Cedergren Karin , He Hans
Published: August 2023

In this work we investigate the long-term stability of epitaxial graphene (epigraphene) quantum Hall resistance standards, including single devices and an array device composed of 236 elements providing R
K/236 ≈ 109 Ω, with R
K the von Klitzing constant. All devices utilize the established technique of chemical doping via molecular dopants to achieve homogenous doping and control over carrier density. However, optimal storage conditions and the long-term stability of molecular dopants for metrological applications have not been widely studied. In this work we aim to identify simple storage techniques that use readily available and cost-effective materials which provide long-term stability for devices without the need for advanced laboratory equipment. The devices are stored in glass bottles with four different environments: ambient, oxygen absorber, silica gel desiccant, and oxygen absorber/desiccant mixture. We have tracked the carrier densities, mobilities, and quantization accuracies of eight different epigraphene quantum Hall chips for over two years. We observe the highest stability (i.e. lowest change in carrier density) for samples stored in oxygen absorber/desiccant mixture, with a relative change in carrier density below 0.01% per day and no discernable degradation of quantization accuracy at the part-per-billion level. This storage technique yields a comparable stability to the currently established best storage method of inert nitrogen atmosphere, but it is much easier to realize in practice. It is possible to further optimize the mixture of oxygen absorber/desiccant for even greater stability performance in the future. We foresee that this technique can allow for simple and stable long-term storage of polymer-encapsulated molecular doped epigraphene quantum Hall standards, removing another barrier for their wide-spread use in practical metrology.
Real-time Monitoring Algorithm of Muscle State Based on sEMG Signal
Authors: Pang Peng , Wei Xiwen , Yang Xinnian
Published: August 2023

Muscle fatigue can occur when we do too much physical activity in a short period of time, or if we have not been exercising regularly. For patients who need rehabilitation training, muscle fatigue has certain safety risks. Therefore, real-time monitoring of muscle fatigue is very necessary and meaningful. At present, there are few studies on the assessment of muscle status, and most of the methods are limited to the detection of fatigue threshold, lagging behind the occurrence of fatigue. This paper analyzes the change law of the fatigue process model and summarizes it, and designs it into a real-time evaluation algorithm of muscle state. First, the autoregressive moving average (ARMA) model is constructed utilizing surface electromyography (sEMG) and joint motion angle data. Next, the parameters are identified and monitored in real-time. Finally, hierarchical clustering is employed to categorize levels of fatigue. The algorithm is capable of capturing changes in fatigue-induced correlations between sEMG and the corresponding joint motion angles during dynamic movements, enabling accurate classification of muscle fatigue states. Experimental results have demonstrated the effectiveness of the algorithm, which has significant implications for real-time evaluation of human muscle state and the design of control systems in human-computer interaction.
Implementation and Design of Metro Process Quality Inspection System based on Image Processing Technology
Authors: Huang Lizhong , Zhang Quanwei
Published: August 2023

In recent years, China’s subway industry has entered a phase of rapid development, and at the same time, the commissioning of large-scale new lines has brought huge challenges to production and operation. In the quality inspection system of subway process, the traditional way is to use human as the carrier of quality inspection, but with the input of large-scale production lines, the manual inspection method is far from meeting the needs of industrial production. Based on the above background, this paper applies image processing technology to the quality inspection process of subway process, and completes the design and implementation of the quality inspection system of subway process based on image processing. In this paper, a lightweight feature-enhanced convolutional neural network model is proposed under the premise of ensuring efficiency. The model deepens the structure of the backbone feature extraction network, adds another prediction scale layer, realizes three-scale prediction, and enhances the semantic information of the shallow feature map, thus improving the detection accuracy of small-scale defects. At the same time, the algorithm has room for optimization and improvement in “identification of anti-loosening wire” and “accurate positioning of through-hole gaskets and washers without missing”.
Image Enhancement Algorithm of Foggy Sky with Sky based on Sky Segmentation
Authors: Sun Wei , Wu Jianli , Rashid Haroon
Published: August 2023

In recent years, image defogging has become a research hotspot in the field of digital image processing. Through defogging enhancement processing, the visual quality of foggy images can be significantly improved, and it is also an important part of subsequent image processing. To overcome the limitations of traditional image dehazing, an image enhancement algorithm for foggy image with sky based on sky segmentation is proposed. Firstly, based on K-means clustering and sky feature analysis, sky region recognition is performed for fog image with sky. Secondly, according to the pixels of sky region, the rough transmittance is corrected, and the dehazing image is obtained by dark channel prior image dehazing based on guided filter. Finally, the dehazing image is equalized by bi-histogram equalization. This algorithm effectively avoids the problem of color distortion and halo caused by the traditional dark channel prior dehazing algorithm in the sky area, and makes the restored foggy image have better global and local contrast.
A Camera Calibration Method for Limited Motion of Target in Space
Authors: Dang Zhiyuan , Yuan Yun , Geng Nan , Khel Naveed Ullah Kaka
Published: August 2023

In modern industrial production, vision measurement systems are widely used for product quality inspection. Camera calibration is a crucial step in vision measurement systems that directly affects the accuracy of measurement results. However, in practical applications, the limited space for measurement and restricted movement of calibration targets present new challenges for camera calibration. In this paper, we propose a camera calibration method that is suitable for calibration targets with limited movement space. This method only requires one image of the calibration target to complete system calibration, greatly simplifying the on-site calibration work. Experimental results show that our method has a re-projection error of 0.0187 pixels, indicating high reliability and applicability. The application of this method in the inspection of seamless steel pipes demonstrates its potential for practical industrial production.
Scratch Detection Method of Shaft Parts Based on Improved YOLOv5
Authors: Bai Haodong , Chen Guanyu , Fu Huiting , Liu Changying
Published: August 2023

The pre-extracted target object is always distorted due to many parts spots, surface reflection and other factors in traditional visual inspection. Therefore, a detection process based on improved YOLOv5 is proposed. In the early stage, for the optimization of light source, the circular light is generally used to successfully extract the region of interest, so as to reduce the scratches caused by image pretreatment, resulting in detection omission and distortion. Adding the ACON (All Class in One Network, ACON) activation function can improve the network feature extraction ability and the accuracy of the detection algorithm. Bounding box loss, means of target detection loss and classification loss are all significantly improved by the improved algorithm, far exceeding the performance of traditional detection methods, and all have a certain degree of reduction.
Design of Solar Endurance Control for Unmanned Aerial Vehicles based on Schmidt Trigger Control
Authors: Hu Xusheng , Liu Juan , Kocheril Rajesh
Published: August 2023

In order to improve the endurance of unmanned aerial vehicles (UAVs), a power supply controller with automatic switching between solar energy and battery was designed. The controller is mainly composed of an AT89C51 single chip microcomputer. By collecting ambient light intensity and comparing it with the preset light intensity of the system, the controller completes automatic switching of the power supply for solar unmanned aerial vehicles, thereby achieving continuous and stable power supply for solar unmanned aerial vehicles. In addition, the implementation method of the single-chip microcomputer program in the controller is also introduced. The control core is to use Schmidt de shake control to switch between solar energy and battery, and to test the various functions of the controller through the flight experiment of a small solar powered unmanned aerial vehicle. Tests have found that solar powered drones using this controller can navigate for a long time in weather with varying light intensity, and the device operates well, effectively improving the power stability of solar powered drones.
LSTM-based Fault Prediction for Ship Power Systems
Authors: Zhang Yi , Chen Ning , Jiang Yuhang , Adeshara Jatinkumar V
Published: August 2023

A ship power system refers to an isolated grid consisting of power generation, electrical energy conversion, transmission, distribution, and consumption. As the heart of the ship’s route, the ship’s power station should try to avoid malfunction, and the malfunction should be quickly investigated and recovered. In this paper, a stand-alone system of a ship power station is built for simulation using the Simulink software platform, and the fault voltage and current parameters of each phase are selected as the source of the data set and input to the Long Short Term Memory (LSTM) neural network algorithm for training and diagnostic prediction of faults. By comparing the diagnostic results with those of Back Propagation (BP) neural network, the results show that LSTM has an accuracy of 98.334%, which can diagnose the failure modes of ship power stations more accurately and has higher explanatory power for the predicted data.
Research on Evolvable Hardware Based on Improved Evolutionary Strategy
Authors: Zhu Min , Tang Long
Published: August 2023

Evolvable hardware (EHW) attracts a lot of researchers because of its excellent adaptive and self-organizing ability. Various of studies have been carried out to improve the evolutionary efficiency. There are mainly two ways: improving the structure of reconfigurable hardware and optimizing evolutionary algorithms. In this paper, we design the reconfigurable circuit based on the systolic array which could reduce the length of circuit coding. And then, an improved evolutionary strategy is proposed, which refers to the yin-yang pair optimization algorithm (YYPO). It can accelerate the evolutionary process and avoid the stalling effect by balancing the relationship between exploration and development. Some experiments were conducted to verify the effect and the results show that the improved method has better searching ability than the traditional evolutionary strategy.
Stroke Prediction Using the Trust Evaluation with Data Leakage Avoiding
Authors: Ye Xiaoyan , Xu Wenchao , Ye Xiaoying , Long Dan , Yin Qiuyang , Huang Binhua
Published: August 2023

Early detection of the severe disease -- stroke is a key step toward effective treatment. Stroke disease data is imbalanced and normally contains the majority of negative cases (without stroke) and the minority of positive cases (stroke). Previous work has used SMOTE to deal with imbalanced data, but most researchers have implemented it for the entire dataset, which means the “answer” was silently “be told” and saved in the entire data, causing data leakage. Moreover, the previous work uses accuracy only as the metrics make the result less guaranteed. We propose a method using the SMOTE applied to the training set only and apply 13 machine learning classifiers for predicting stroke. We combine the AUC with accuracy as evaluation metrics in the stroke prediction task, which can elevate the confidence level of the assessment of results. The experiment shows that misused SMOTE and standardization can cause data leakage and the combined metrics can evaluate models with higher trustworthiness. We conclude that using our method can avoid data leakage and assess the model with higher trustworthiness.
Control Strategy of Circulating Current Suppression for Modular Multilevel Converter
Authors: Wang Xiaolei , Zheng Quan , Zhong Jianying , Zhang Lixin , Wang Zhijun , Wang Nan , Yan Dengke
Published: August 2023

The structural characteristics of modular multilevel converters (MMC) lead to circulating current problems, which increases the requirements for device capacity and withstand voltage levels. Therefore, this paper proposes a circulating current suppression strategy based on new sliding mode control. This strategy uses a variable approach rate to reduce chattering caused by sliding mode control. Compared with the circulating current suppression strategy using traditional PI control, it enhances the anti-interference of the circulating current suppression strategy. Finally, this paper builds the MATLAB/Simulink simulation model and experimental platform. The results show that the strategy has good anti-interference performance.
Implementation of Control Standardization Based on HCM5000G DC Control and Protection Platform
Authors: Yang Chengfei , Liu Xuhui , Li Fengqi , Li Jun , Feng Xuan , Gu Xianghong
Published: August 2023

This paper introduces the whole construction of the control standardization simulation system based on the HCM5000G DC control and protection platform, which can meet the requirements of engineering design and various control performance indexes by adopting the standardization design of the self-control and localization platform. In this paper, the construction principle of the standardized control system and the optimization strategy of the control structure are discussed in detail, and the engineering simulation model is realized by using the real-time digital simulation system with the layered and distributed standardized interface design, which provides an important reference for the future large-scale application of the control and protection of DC Engineering.
Fault Diagnosis Strategy for Solar Cells Based on Reverse Derivation of I-V Curve
Authors: Sun Min , Zhao Huaxing , Chen Bo , Zeng Wei , Yang Zaineng
Published: August 2023

This paper proposes a fault diagnosis strategy for solar cells based on the reverse derivation of the I-V curve. This strategy does not require real-time monitoring of the surface irradiance and average temperature of the solar cell during operation. It only needs to calculate(establish) the I-V curve library under different irradiance and solar cell temperature in advance, then measure the open circuit voltage and short circuit current of the photovoltaic module during operation. And the measured voltage and current at the maximum power point can determine whether the solar cell is faulty. The possible faults of various solar cells are simulated by setting up experimental equipment, and the method is used for fault diagnosis. Experimental results show that the proposed method can effectively monitor various faults of solar cells. The method improves the accuracy of fault detection of the solar cell, enhances the reliability and economical benefits of the photovoltaic power station, and realizes online fault detection of the solar cell.
An Improved Loss Calculation Method for MMCs
Authors: Song Yonghui , Xiong Xiaofu
Published: August 2023

Accurate loss calculation of power devices in the submodules of the modular multilevel converter (MMC) is significant. The loss calculation of MMC is closely related to its control strategies, such as the nearest level modulation (NLC) method and the capacitor voltage balancing method based on sequencing. The loss distribution characteristics and calculation of power devices are different in different control methods, and the loss distribution characteristics are complex and difficult to calculate. This shorting adversely affects MMC parameter design and reliability analysis. However, the existing methods cannot achieve an accurate calculation of MMC loss. To address the above problems, an improved loss calculation method is presented by detailed analyzing the working principle and the loss distribution of variable submodules (SM). The proposed loss calculation method can accurately calculate the power devices’ loss under various control methods and different topologies. The correctness and effectiveness of the improved loss calculation method are verified through Matlab/Simulink software.