bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of light and no‐load operation of a 300 kW resonant single active bridge based on 3.3 kV SiC‐devices
Authors: Fortes G. , Ladoux P. , Fabre J. , Flumian D.
Published: June 2022

The resonant single active bridge topology (R‐SAB) operated in the half‐cycle discontinuous current mode (HC‐DCM) is a very attractive solution due to its high efficiency, low complexity and fixed voltage transfer ratio (DCX). However, as expected for a series‐resonant converter (SRC), its DCX operation depends on the resonant tank circuit‐parameters, parasitic capacitive elements and output load. Specially, at light and no‐load operation, when the system is extremely underdamped, it may present a large output overvoltage due to resonance interactions. This is of prime importance for converters using medium voltage (MV) SiC‐MOSFETs, which feature significant output capacitances that can lead to voltage breakdown of the rectifier semiconductors. Therefore, the supposed fixed‐voltage transfer ratio is not entirely valid and deserves a proper understanding due its criticality. This paper reviews the subject, clarifying its root cause and its multifactorial dependencies. Moreover, it provides a simple solution based on a variable dead‐time with fixed magnetizing current experimentally verified with a 300kW/1.8kV R‐SAB prototype implemented with MV SiC‐devices.
Design method of wide‐band high‐current air‐core inductor EMI filter for high voltage DC power of motor inverter of electric vehicle
Authors: Zhai Li , Yang Shuangjie , Hu Guixing , Lv Mengyuan
Published: June 2022

Passive filters are often used for electromagnetic interference (EMI) suppression of high voltage (HV) DC power supplies of electric vehicle (EV) motor controllers. The high current of the DC bus saturates the differential mode (DM) magnetic ring, while the leakage inductance of common mode (CM) inductor used as the DM inductance is usually very small, resulting in almost no suppression of DM EMI. A design method of broadband high‐current air‐core inductor passive filter is proposed. By using the air‐core inductor as DM inductor, the problem of easy saturation of the DM inductor core and the small leakage inductance of the CM inductor is solved, and improves the low frequency DM EMI suppression. Through the calculation and selection of the turning frequency point of the multi‐stage filter circuit, the effective frequency band can be improved. By analysing the influence of parasitic parameters, the problem of insufficient insertion loss of the filter at high frequency is solved. The experimental verification shows that the proposed air‐core inductor filter achieves 50 dB of CM and DM insertion loss in frequency range of 150 kHz–108 MHz, and meets the requirements of system conducted disturbance voltage specified in CISPR25‐2016Rd level 3.
X-ray spectra of the Fe-L complex
Authors: Gu L. , Shah C. , Mao J. , Raassen A. J. J. , de Plaa J. , Pinto C. , Akamatsu H. , Werner N. , Simionescu A. , Mernier F. , Sawada M. , Mohanty P. , Amaro P. , Gu M. F. , Porter F. S. , López-Urrutia J. R. C. , Kaastra J. S.
Published: June 2022

There has been a growing request from the X-ray astronomy community for a quantitative estimate of systematic uncertainties originating from the atomic data used in plasma codes. Though there have been several studies looking into atomic data uncertainties using theoretical calculations, in general, there is no commonly accepted solution for this task. We present a new approach for estimating uncertainties in the line emissivities for the current models of collisional plasma, mainly based upon a dedicated analysis of observed high resolution spectra of stellar coronae and galaxy clusters. We find that the systematic uncertainties of the observed lines consistently show an anticorrelation with the model line fluxes, after properly accounting for the additional uncertainties from the ion concentration calculation. The strong lines in the spectra are in general better reproduced, indicating that the atomic data and modeling of the main transitions are more accurate than those for the minor ones. This underlying anticorrelation is found to be roughly independent of source properties, line positions, ion species, and the line formation processes. We further applied our method to the simulated XRISM and Athena observations of collisional plasma sources and discuss the impact of uncertainties on the interpretation of these spectra. The typical uncertainties are 1–2% on temperature and 3–20% on abundances of O, Ne, Fe, Mg, and Ni.
Case study: Influence of the Mechanical and Electrical Anti-rollback System for Wheelchair When Climbing a Hill
Authors: Wieczorek Bartosz
Published: June 2022

The article deals with the issues of operating wheelchairs with manual drive in areas with a significant inclination angle. The kinematics of a wheelchair while climbing a hill was analyzed. On the basis of the conclusions drawn from the research, two solutions for systems that block the reversal of a wheelchair on a hill have been proposed. Among the solutions mentioned, a mechanical anti-rollback system with three operating modes and an electric anti-rollback system is described. The described electric anti-rollback system is part of a manual-electric hybrid drive unit to the manual wheelchairs.
The Concept of Structure a Flexible Design and Manufacturing Method Focused on the Individual Production of Grippers
Authors: Dudziak Marian , Talaśka Krzysztof , Wilczyński Dominik , Marchwicki Tomasz
Published: June 2022

The issues presented herein cover the design and manufacture of gripping devices. The main considerations include individual geometric and material solutions as well as specialized constructions intended for specific, custom and clearly defined orders. The work presents the concept of the design and manufacture of grippers, consisting of several basic, interconnected stages. The purpose thereof is the implementation of a flexible production system at a small enterprise Ankotech. An algorithm for design and manufacturing employing manipulators and Binar products has been proposed and presented. The proposed flexible design and manufacturing algorithm of grippers employing Binar manipulators and products constitutes an innovative solution.
Finite Element Analysis of the Axially Non-symmetrical Piercing Punches Performance for Belt Perforation
Authors: Wojtkowiak Dominik , Talaśka Krzysztof
Published: June 2022

Modification of the punch geometry can greatly reduce the force necessary to perform the perforation of the belt. This paper presents research on axially non-symmetrical piercing punches – double sheared one and one with a cylindrical bowl. FEM analysis was performed for a variable tip angle β in the 60-150° range for a double sheared punch or a variable bowl radius R in the 5.25-10 mm range and for a constant punch diameter D = 10 mm and TFL10S belt. Based on the obtained results, the influence of the tip angle β (for the double sheared punch) and the bowl radius R (for a cylindrical bowl punch) on the perforation force FP and pneumatic cylinder stroke increase Δs was determined. FEM analysis was used to obtain the perforation force in function of punch displacement characteristics for various tool geometry. Based on the results, the characteristics of the perforation force in function of punch geometrical parameters were determined. Additionally, their application in the punching die design process, where the effective geometrical features of the tools are desired, is presented.
Numerical analysis and optimization of large dimensioned structures considering stress concentrations in welded joint
Authors: Majko Jaroslav , Sága Milan , Ságová Zuzana , Handrik Marián , Kopas Peter , Jakubovičová Lenka
Published: June 2022

The paperpresents an optimal design and computational solution of truss structures consideringstress concentrations in welded joints. The calculation approach for precise analysis of welded joints using finite element method is introduced. The standard finite element analysis of the truss structure is followed by a special calculation procedure. The procedure is based on the known method of sections. Each member of the truss structure joined at the point under investigation is sectioned off the entire structure. In the next step, a new detailed finite element model of the welded joint is created. These analysis results allow define the stress concentration factors for technical problems of this type. Finally, a specific optimization procedure for design of structures based on the principles of discrete optimization is shown.
Analysis of Stress Intensity Factor on Weld Surface
Authors: Handrik Marián , Majko Jaroslav , Kopas Peter , Vaško Milan , Sága Milan , Jakubovičová Lenka
Published: June 2022

Progressive welding technologies based on high energy density welding process such as electron beam welding allow joining two materials without consumable. The nature of the process is the deposition of energy to the small areas, which leads to the creation of a narrow heat-affected zone (HAZ). Therefore, a prime example of surface weld defects in the case of the beam electron welding technology are cracks in the material. The article is focused on the preparation of a computational model that comprises a precise description of welding joint shape. The accurate model description was acquired using 3D scanning. In the next step, the data are subsequently modified in MATLAB and ADINA for model simplification. The performed analysis of results shows a significant influence of the weld surface on the occurrence of stress concentrations in the weld zone.
Impact of Geometry on the Thermal and Mechanical Properties of Periodic Surface Structures: A Numerical Study
Authors: Gawrońska Elżbieta , Dyja Robert
Published: June 2022

Periodic Surface Structures (PSS) fabricated via Additive Manufacturing (AM) have recently emerged as being appropriate candidates for high-value engineered structures. Among the many PSS designs, gyroid structures have demonstrated merits in mechanical properties and permeability compared to traditional lattice structures. Periodic surface structures are mathematically formulated by geometric factors: surface thickness, sample size, number of surface periods, or unit cells. These elements produce a continuous sur-face with specific topology. Numerical simulations of the effect of modulating these factors on overall thermal and mechanical properties require substantial computational resources and give a quite good qualitative assessment. Cubic P-surface (“Primitive”), D-surface (“Diamond”), and gyroid surface structures of various designs were simulated under load and heat transport using a numerical approach. The influence of geometric factors on thermal and mechanical behavior was determined qualitatively. The results show the impact of the number of cells and surface thickness on both thermal and strength modulus. The paper focuses on thermal and mechanical analysis of periodic surface structures. The study is conducted by solving the stress and heat equations using the Finite Element Method (FEM) and is achieved with the use of our authorial software. Our software module generates periodic surface structures and simulates stress and temperature distribution in it. The stress model is defined by dependence between stress and strain, it got from an experiment, and the correlation of strain and displacement got from geometric conditions. In the paper, we present calculations for three-dimensional systems in which we analyze the stress and temperature distribution depending on the geometric factors. The results presented allow estimation of the behavior of periodic surface structures under loads. It intends to evaluate the possibility of crack occurrence in complex structures based on the performed numerical simulations in future work.
Simulation of Kinematic and Strength Analysis of a Conical Shredder
Authors: Lewandowski Jakub , Łączny Daniel , Bałdowska-Witos Patrycja , Kruszelnicka Weronika
Published: June 2022

The paper presents the opportunities for the adjustment of operating parameters and constructional parameters of shredders for polymer materials using CAD/CAE tools. The object of research is a conical shredder developed on the basis of a patent. For studies SolidWorks application with simulation and motion option has been used.
Analysis of Wedge Lock Washer using the Finite Element Method
Authors: Konecki Karol , Talaśka Krzysztof
Published: June 2022

Washers with a so-called wedge-locking effect are available for the engineering industry. The manufacturer assures, as confirmed by the Junker vibration test, that the tension in the thread increases when the screw is unscrewed. This is due to the appropriate geometry of the washers, which always work together in pairs. On the outside, the washers have serrations which, when tightening the screw, cut into the material of the clamped part, leaving a permanent plastic deformation. On the inside they have wedges, the angle of which is greater than the angle of the helix of the thread. The subject of this work is a study of creating a simulation model that takes into account the discussed effect of wedge lock of the washers. This model will be used in the future for simulation tests of washers with a different geometry than the one proposed by the manufacturer.
Past, Present and Future of Assistive Robotic Lower Limb Exoskeletons
Authors: Narina Ramesh , Iwaniec Marek , Arawade Swapnil
Published: June 2022

Many research teams have developed various innovations in the field of assistive robotic exoskeletons for human lower limbs. Especially in the recent years, because of the expeditious technological development, much work has been done and published in the scientific communities. However, in the publications, for different reasons and constraints, the information available is in bits and pieces. Most papers only could manage to speak of the individual aspects like the mechanical design or state machine or interface or another control scenario, etc. This is why an attempt of bringing scientific aspects together is done in this work. This is achieved by considering the most popular and various kinds of exoskeletons. Therefore, in this chapter an overview on the aspects of mechanical design and electrical control, and simultaneously their algorithms were discussed. Coming to analytical simulations like forward and inverse kinematics, dynamic simulation of the moments of the multibody system, etc., were performed in ADAMS and OpenSim simulation platforms. Better solutions were proposed and awaiting challenges were discussed for each aspect of the robotic exoskeleton.
Concept and Design of the Test Bench for Electrostatic Separation in Plastic Recycling Application
Authors: Czarnecka-Komorowska Dorota , Jędryczka Cezary , Sędziak Dariusz , Regulski Roman , Netter Krzysztof , Rybarczyk Dominik , Barański Mariusz , Barczewski Mateusz
Published: June 2022

Plastics recycling has become a key industry in developed countries, to reduce ecological damage and save non-renewable resources. This paper discusses the concept and the design of electrostatic separator as a test bench for the separation of different plastics in recycling applications. In the automotive recycling process, all these waste materials must be processed further for re-entering the cycle or thermal utilization. The following application presents the possibility of research and technological tests by changing several parameters, such as a position of the electrodes, control of the polarity and voltage, variable speed of feeder and drum, and also tribo-electrification parameters (time, intensity). The impact of process parameters on the efficiency of the plastic separation can be analyzed by the developed a specialized computer vision system. The preliminary results of conducted tests showed that separation is dependent on many variations of parameters. The results of this study indicate that the proposed innovative design of the research stand ensures the high research potential of the proposed equipment.
Comparison of the Optical Lock-in Thermography using the Reflection Mode and the Transmission Mode
Authors: Stalmach Ondrej , Dekys Vladimir , Straka Vaclav , Stalmachova Katarina
Published: June 2022

Optical lock-in thermography is a non-destructive testing method. The surface of the sample is excited using the thermal waves and the response is recorded by the thermal camera. This image thermal sequence is processed using the image processing method named lock-in method. Optical lock-in thermography can be used to detect cracks and damages in metal or composite material. Two position modes are used: the reflection and the transmission mode. In this paper, are compared these two modes. An experiment is carried out on a printed composite plane with the square blinded holes placed in the different depths below the surface. The phase images are created using the lock-in method for both position modes. The results are compared and the advantages and the disadvantage of these position modes find out.
Research on Load on the Roll Press’ Shafts and Work Items
Authors: Kosturkiewicz Bogdan , Janewicz Andrzej , Kosturkiewicz Mateusz
Published: June 2022

The results of a method used in evaluating the load on roll press’ shafts used in briquetting fine-grained materials are presented. The research was conducted in the Manufacturing Systems Department at AGH University of Science and Technology in Kraków. The research provided an insight into choosing a power plant and design features of the roll press and determining the processing parameters.
Modelling the Electricity Consumption in a Manufacturing Company through Probability Distribution
Authors: Michalková Mária , Pobočíková Ivana , Sedliačková Zuzana
Published: June 2022

The paper deals with model of electricity consumption in a company providing hot and cold forming. As modelled data, there were used hourly records of electricity consumed in the manufacturing processes. The data covered working hours over a year. The probability distributions, chosen for modelling, were normal distribution, gamma distribution, logistic distribution, Weibull distribution and Rayleigh distribution. The goodness of fit of these distributions was judged based on the values of the information criteria (AIC, AICc and BIC), coefficient of determination (R2) and the root mean square error (RMSE). According to these criteria, the best fit was achieved by the two-parameter Weibull distribution.
An efficient gradient method with approximately optimal stepsizes based on regularization models for unconstrained optimization
Authors: Liu Zexian , Chu Wangli , Liu Hongwei
Published: June 2022

It is widely accepted that the stepsize is of great significance to gradient method. An efficient gradient method with approximately optimal stepsizes mainly based on regularization models is proposed for unconstrained optimization. More specifically, if the objective function is not close to a quadratic function on the line segment between the current and latest iterates, regularization model is exploited carefully to generate approximately optimal stepsize. Otherwise, quadratic approximation model is used. In addition, when the curvature is non-positive, special regularization model is developed. The convergence of the proposed method is established under some weak conditions. Extensive numerical experiments indicated the proposed method is very promising. Due to the surprising efficiency, we believe that gradient methods with approximately optimal stepsizes can become strong candidates for large-scale unconstrained optimization.
Scutellaria baicalensis Pith-decayed Root Inhibits Macrophage-related Inflammation Through the NF-κB/NLRP3 Pathway to Alleviate LPS-induced Acute Lung
Injury
Authors: Zhang Fanglei , Ke Chang , Zhou Zhongshi , Xu Kang , Wang Yan , Liu Yanju , Tu Jiyuan
Published: June 2022

Acute lung injury (ALI) is one of the representative “lung heat syndromes” in traditional Chinese medicine (TCM). Scutellaria baicalensis is an herbal medicine used in TCM for
treating lung diseases, due to its remarkable anti-inflammatory and antiviral effects. When used in TCM, S. baicalensis root is divided into two categories: S. baicalensis
pith-not-decayed root (SN) and S. baicalensis pith-decayed root (SD). Compared to SN, SD has a better effect on lung diseases. We constructed a lipopolysaccharide (LPS)-induced acute
lung injury (ALI) mouse model to study the pharmacodynamic mechanism of SD. The ethanolic extract of Scutellaria baicalensis pith-decayed root (EESD) significantly affected
LPS-induced ALI by reducing alveolar interstitial thickening, pulmonary edema, and other pathological symptoms, decreasing the infiltration of inflammatory cells, especially macrophages, and
inhibiting IL-1β, TNF-α, and IL-6 transcription and translation. Furthermore, in the THP-1 macrophage model induced by LPS, EESD inhibited the expression of phosphorylated
nuclear factor inhibitory protein alpha (p-IκBα), phosphorylated nuclear factor-κB P65 (p-p65), cleaved-caspase-1, cleaved-IL-1β protein, and the release of
inflammatory factors in the NF-κB/NLRP3 pathway, inhibiting macrophage function. In vivo experiments yielded similar results. Therefore, the present study clarified the
potential of EESD in the treatment of ALI and revealed its potential pharmacodynamic mechanism by inhibiting the NF-κB/NLRP3 inflammasome pathway and suppressing the pro-inflammatory
phenotype activation of lung tissue macrophages.
Risk Factors of Cardiovascular Death after Venous Thromboembolism: Results from a Prospective Cohort Study
Authors: Noumegni Steve Raoul , Mansourati Vincent , Tromeur Cécile , Mao Raphael Le , Hoffmann Clément , Moigne Emmanuelle Le , Nasr Bahaa , Gentric Jean-Christophe , Guegan Marie , Poulhazan Elise , Bressollette Luc , Lacut Karine , Couturaud Francis , Didier Romain
Published: June 2022

Background Cardiovascular deaths (CVDTs) are more frequent in patients with venous thromboembolism (VTE) than in the general population; however, risk factors associated with this increased risk of CVDT in patients with VTE are not described.

Methods To determine the risk factors of CVDT in patients with VTE from a multicenter prospective cohort study, Fine and Gray subdistribution hazard models were conducted.

Results Of the 3,988 included patients, 426 (10.7%) died of CVDT during a median follow-up of 5 years. The risk factors of CVDT after multivariate analyses were: age of 50 to 65 years (vs. <50 years, hazard ratio [HR]: 3.22, 95% confidence interval [CI]: 1.67–6.62), age >65 years (vs. <50 years, HR: 7.60, 95% CI: 3.73–15.52), cancer-associated VTE (vs. transient risk factor-related VTE, HR: 1.73, 95% CI: 1.15–2.61), unprovoked VTE (vs. transient risk factor-related VTE, HR: 1.42, 95% CI: 1.02–2.00), past tobacco use (vs. never, HR: 1.43, 95% CI: 1.06–1.94), current tobacco use (vs. never, HR: 1.87, 95% CI: 1.15–3.01), hypertension (HR: 2.11, 95% CI: 1.51–2.96), chronic heart failure (HR: 2.28, 95% CI: 1.37–3.79), chronic respiratory failure (HR: 1.72, 95% CI: 1.02–2.89), and atrial fibrillation (HR: 1.67, 95% CI: 1.06–2.60). The risk of CVDT was significantly reduced with direct oral anticoagulants (vs. vitamin-K antagonists) and with longer duration of treatment (>3 months).

Conclusion Risk factors of CVDT after VTE include some traditional cardiovascular risk factors and other risk factors that are related to characteristics of VTE, and patients' comorbidities.
Beyond the dikes: an institutional perspective on governing flood resilience at the Port of Rotterdam
Authors: Punt Eline , Monstadt Jochen , Frank Sybille , Witte Patrick
Published: June 2022

Seaports, infrastructural nodes in global supply chains and production processes, are vulnerable to flood risks: they are crisis-prone critical infrastructure (CI) systems. However, the governance of their flood resilience involves many different private and public actors in a complex institutional environment and there is no scholarly consensus about how resilience can be successfully governed. We investigate the governance of flood resilience at the Port of Rotterdam (PoR) from an institutional perspective, by studying institutional arrangements for flood resilience within and across vertical, horizontal and territorial dimensions to elucidate the strengths and ongoing challenges of shaping the port’s flood resilience. We conducted semi-structured expert interviews (n = 17) and an analysis of policy documents and legislation (n = 33) relating to flood risk management and CI protection. We find that the institutional design for flood resilience in the Netherlands consists of a complex matrix of responsibilities, capacities and plans. While coordination is visible in the shared visions and strategies for flood resilience developed at different policy levels and domains, we find fragmentation and persisting institutional challenges, including siloed governance approaches, knowledge gaps and blurred distribution of responsibilities; these are significant barriers to enhancing flood resilience for CIs and port–city relationships.
Propagation of Compressional Alfvén Waves in a Magnetized Pair Plasma Medium
Authors: Rajib T. I. , Sultana S.
Published: June 2022

The reductive perturbation approach was used to explore the nonlinear propagation of fast (compressive) and slow (rarefactive) electron–positron (EP) magnetoacoustic (EPMA) modes in an EP plasma medium. The solitary wave solution of the Korteweg-de Vries (K-dV) equation is used to identify the basic properties of EP compressional Alfvén waves. It is shown that the fast (slow) EPMA mode is predicted to propagate as compressive (rarefactive) solitary waves. The basic features (i.e., speed, amplitude, and width) of the compressive (i.e., fast) EPMA waves are found to be completely different from those of rarefactive (i.e., slow) EPMA ones. It is also examined that hump (dip) shape solitary waves are found for the fast (slow) mode. The significance of our findings is in understanding the nonlinear electromagnetic wave phenomena in laboratory plasma and space environments where EP plasma may exist.
Control of afterbody vortices from a slanted-base cylinder using sweeping jets
Authors: Chen Xiaodong , Zhong Shan , Ozer Ozgun , Weightman Andrew
Published: June 2022

In this paper, a sweeping jet is applied to control the afterbody vortices behind a slanted-base cylinder for the first time at Reynolds numbers from 87 000 to 200 000. The control effects are examined using stereo particle image velocimetry and surface pressure measurements with the jet momentum coefficient (Cμ) varying from 0.056 to 0.893. It is found that the sweeping jet results in increasingly diffused and larger afterbody vortices as Cμ increases. While an increase in Cμ up to 0.167 leads to a reduction in the circulation of the afterbody vortices and their earlier detachment from the slanted base, a further increase in Cμ introduces additional vorticity into the afterbody vortices leading to higher vortex strength, which could be detrimental to the control purpose. The interaction mechanism of sweeping jets lies in that turbulence is injected into the afterbody vortices as the sweeping jet intersects with these vortices and this subsequently causes diffusion of velocity gradient in the vortices, which weakens their strength. As the sweeping jet spreads itself sideways, while it propagates downstream along the endplate, it pushes the afterbody vortices upward and to the side. The impact of the sweeping jet has resulted in the dominant vortex wandering frequency of the afterbody vortex being locked to that of the sweeping jet. This also causes the afterbody vortices detach themselves from the endplate earlier resulting in a shorter low-pressure footprint on the surface.
Amplitude and phase relation of harmonics in nonlinear focused ultrasound
Authors: Wu Delin , Gao Shenping , Li Jian , Yao Lei , Yu Xingyan , Zhang Zhikai , Zhang Hengda , Wang Xiaobo
Published: June 2022

High intensity focused ultrasound has gained rapid clinical acceptance as a noninvasive treatment for solid tumors. As implied by the name, the intensity of sound at the focus is generally large. In a nonlinear ultrasound field, where the acoustic spectrum contains a considerable spread of harmonics, the pressure waveform is asymmetrically distorted, with a discrepancy between the peak compressional pressure and the peak rarefactional pressure, which are required in FDA and IEC regulations. Therefore, the amplitude and phase of the harmonics matter. In order to better understand nonlinear focused ultrasound, the amplitude and phase relation of the harmonics are investigated through both numerical simulations and measurements. The first three harmonics are extracted from the distorted wave by a zero-phase band-pass filter. It is demonstrated that, as the source pressure increases, the focusing gain for the fundamental component tends to decrease while the focusing gains for the second and third harmonics rise. The relative phases show very little change. There is a substantive agreement between the simulated and measured results for the focusing gain of the harmonics. The relative phase of the harmonics needs to be further verified after the calibration of the phase response of the hydrophone is well-developed.
Numerical simulation of flow past two staggered circular cylinders at a subcritical regime
Authors: Xiong Zhongying
Published: June 2022

In this paper, the author numerically investigates the effect of a staggered arrangement on the vortex shedding of two circular cylinders with unequal diameters under a subcritical Reynolds number. The results show that the interference between the large and small cylinders was prominent at a positional angle of α = 30°. The time histories of the lift and drag coefficients exhibited severe anomalous jumps, and the number of dominant shedding frequencies of the vortices shed from the small cylinder was usually two and three. As the gap ratio (G/D) became greater than 0.75, the time histories of the lift and drag coefficients at α = 60°, 120°, and 150° tended to become stable with the weakening of the interference between the large and small cylinders. When α = 150°, the modes of action of flow in the gap for the large and small cylinders were similar under different gap ratios. The Strouhal number of the large cylinder was in the range of 0.18–0.23 overall while that of the small cylinder gradually approached 0.2 with an increase in G/D when α = 60°–150°.
Uncertainty quantification of turbulent systems via physically consistent and data-informed reduced-order models
Authors: Charalampopoulos A. , Sapsis T.
Published: June 2022

This work presents a data-driven, energy-conserving closure method for the coarse-scale evolution of the mean and covariance of turbulent systems. Spatiotemporally non-local neural networks are employed for calculating the impact of non-Gaussian effects to the low-order statistics of dynamical systems with an energy-preserving quadratic nonlinearity. This property, which characterizes the advection term of turbulent flows, is encoded via an appropriate physical constraint in the training process of the data-informed closure. This condition is essential for the stability and accuracy of the simulations as it appropriately captures the energy transfers between unstable and stable modes of the system. The numerical scheme is implemented for a variety of turbulent systems, with prominent forward and inverse energy cascades. These problems include prototypical models such as an unstable triad system and the Lorentz-96 system, as well as more complex models: The two-layer quasi-geostrophic flows and incompressible, anisotropic jets where passive inertial tracers are being advected on. Training data are obtained through high-fidelity direct numerical simulations. In all cases, the hybrid scheme displays its ability to accurately capture the energy spectrum and high-order statistics of the systems under discussion. The generalizability properties of the trained closure models in all the test cases are explored, using out-of-sample realizations of the systems. The presented method is compared with existing first-order closure schemes, where only the mean equation is evolved. This comparison showcases that correctly evolving the covariance of the system outperforms first-order schemes in accuracy, at the expense of increased computational cost.
Consumable Reading and Children's Literature
Authors: Veryeri Alaca Ilgım
Published: June 2022

Consumable Reading and Children's Literature explores how multisensory experiences enhance early childhood literacy practices through material and sensory interactions. Embodied engagements that focus on the gustatory experience and, in particular, the sense of taste are investigated by studying food-related narratives. Children’s literature and different reading scenarios involving consumable objects, packages, tableware and utensils are scrutinized. Surfaces, the underlying mechanisms that support children’s literature, are considered in connection to emerging media and groundbreaking technologies. The interdisciplinary nature of this work draws on material and surface science, human-computer interaction, arts and food studies. As innovation and everyday materials meet, the potential of hybrid narratives mimicking synesthesia emerges with discussions on cross-modal learning. This monograph will inspire the interest of not only students, teachers, scholars of children’s literature and child development but also researchers and practitioners across various artistic and scientific disciplines.
Coordination in the courtroom
Authors: Kytö Merja
Published: June 2022

Previous research has shown that clausal and phrasal uses of and pattern in ways characteristic of different text types in both Present-day and early English. Speech-based text types such as witness depositions and trial records are likely to show higher rates of clausal uses than written-based texts such as science and history writing. The present study turns to the uses of and in a unique resource, the records from the Salem witchcraft trials in New England (1692–1693), comprising a range of speech-related and written-based text categories. To enable comparisons between early American English and British English usage, comparative material is drawn from the Helsinki Corpus and the Corpus of English Dialogues 1560–1760.
Dialect in early African American plays
Authors: Kautzsch Alexander
Published: June 2022

The sources for the historical reconstruction of African American English (AAE) are manifold, ranging from ex-slave narratives and interviews with hoodoo doctors to blues lyrics, and letters authored by semi-literates. The present article looks into the representation of AAE in a further source, early plays (1858–1938), and investigates non-standard morpho-syntactic features found in these imagined instances of AAE speech. A helpful tool for this task is the list of 235 features used in the World Atlas of Varieties of English (WAVE). The results will be compared to the WAVE features found in the more traditional sources of Earlier AAE speech, which ultimately tackles the question of how close the dialect used in these plays matches non-invented Earlier AAE.
Advanced manufacturing approaches for electrochemical energy storage devices
Authors: Hawes Gillian F. , Rehman Sarish , Rangom Yverick , Pope Michael A.
Published: June 2022

Advancements in electrochemical energy storage devices such as batteries and supercapacitors are vital for a sustainable energy future. Significant progress has been made in developing novel materials for these devices, but less attention has focused on developments in electrode and device manufacturing. While electrodes are traditionally made through slurry casting of electrochemically active material, advanced manufacturing techniques enable patterning of novel electrode architectures and control of device geometries in real-time, which can potentially result in electrodes with increased loading, improved electrochemical performance, and added functionality, such as flexibility and wearability. These inexpensive methods are particularly suited for lab-scale research and start-up companies, as they enable rapid prototyping without a full device production line. The present review describes three main methods of advanced manufacturing (inkjet printing, direct ink writing, and laser-induced graphene techniques) and evaluates the performance of batteries and supercapacitors fabricated via these methods in comparison to traditionally manufactured devices.
Electron tunneling through double-electric barriers on HgTe/CdTe heterostructure interface
Authors: Lin Liang-Zhong , Ling Yi-Yun , Zhang Dong , Wu Zhen-Hua
Published: June 2022

We investigate theoretically the carrier transport in a two-dimensional topological insulator of (001) HgTe/CdTe quantum-well heterostructure with inverted band, and find distinct switchable features of the transmission spectra in the topological edge states by designing the double-electric modulation potentials. The transmission spectra exhibit the significant Fabry–Pérot resonances for the double-electric transport system. Furthermore, the transmission properties show rich behaviors when the Fermi energy lies in the different locations in the energy spectrum and the double-electric barrier regions. The opacity and transparency of the double-modulated barrier regions can be controlled by tuning the modulated potentials, Fermi energy and the length of modulated regions. This electrical switching behavior can be realized by tuning the voltages applied on the metal gates. The Fabry–Pérot resonances leads to oscillations in the transmission which can be observed in experimentally. This electric modulated-mechanism provides us a realistic way to switch the transmission in edge states which can be constructed in low-power information processing devices.
Optical study on topological superconductor candidate Sr-doped Bi2Se3
Authors: Liu Jialun , Wang Chennan , Lin Tong , Cao Liye , Wang Lei , Li Jiaji , Tao Zhen , Shen Nan , Wu Rina , Fang Aifang , Wang Nanlin , Chen Rongyan
Published: June 2022

Utilizing infrared spectroscopy, we study the charge dynamics of the topological superconductor candidate Sr
x
Bi2Se3. The frequency-dependent reflectivity R(ω) demonstrates metallic feature and the scattering rate of the free carriers decreases with temperature decreasing. The plasma edge shows a slight blue shift upon cooling, similar to the behavior of Cu
x
Bi2Se3. As the carrier concentration n obtained by Hall resistivity increases slightly with the decreasing temperature, the effective mass is proved to increase as well, which is in contrast with that of Cu
x
Bi2Se3. We also perform the ultrafast pump-probe study on the Sr0.2Bi2Se3 compounds. Resembling its parent compound Bi2Se3, three distinct relaxation processes are found to contribute to the transient reflectivity. However, the deduced relaxation times are quite different. In addition, the electron-optical-phonon coupling constant is identified to be λ = 0.88.
Spontaneous emission of a moving atom in a waveguide of rectangular cross section
Authors: Zeng Jing , Lu Jing , Zhou Lan
Published: June 2022

We study the spontaneous emission (SE) of an excited nonrelativistic two-level system (TLS) interacting with the vacuum in a waveguide of rectangular cross section. All TLS’s transitions and the center-of-mass motion of the TLS are taken into account. The SE rate and the carried frequency of the emitted photon for the TLS initially being at rest are obtained, it is found that in the first order of the mass M, the frequency of the emitted photon is smaller than the transition frequency of the TLS and the SE rate is smaller than the SE rate Γ
f of the TLS fixed in the same waveguide. The SE rate for the TLS initially being moving is obtained in the second order of the mass M. The SE rate is smaller than Γ
f but it is dependent not only on the atomic mass but also on the initial momentum. The carried frequency of the emitted photon is decreased when it travels along the direction of the initial momentum, whereas it is increased when it travels in the opposite direction of the initial momentum.
Energy levels and magnetic dipole transition parameters for the nitrogen isoelectronic sequence
Authors: Hu Mu-Hong , Wang Nan , Ouyang Pin-Jun , Feng Xin-Jie , Yang Yang , Wu Chen-Sheng
Published: June 2022

Theoretical calculations of the energy levels and magnetic dipole transition parameters for the 1s22s22p3 and 1s22p5 configurations of nitrogen isoelectronic sequence with Z = 21–30 are performed using multi-congfiguration Dirac–Fock (MCDF) method. Based on the relativistic computational code GRASP2k compiled within the framework of MCDF method, the electron correlations, Breit interaction and QED effects are well treated in detail. The energy levels, line strengths and transition rates of magnetic dipole transition are obtained and compared with the experimental data available. For most cases, good agreements are achieved and the relative differences of them are less than 0.114%, 8.43% and 9.80%, respectively. The scaling laws of the fine structure splitting and transition rate are obtained on the isoelectronic sequence and the corresponding physical mechanisms are discussed. The data sets for tables are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00022.
Effect of thickness on magnetic properties of single domain GdBCO bulk superconductors
Authors: Gao Ping , Yang Wan-Min , Wu Ting-Ting , Wang Miao , Liu Kun
Published: June 2022

To study the influence of thickness on the magnetic properties of ReBCO (Re = Y, Gd, Sm, Nd, etc.) bulk superconductors, a single domain gadolinium barium copper oxide (GdBCO) bulk superconductor fabricated by the Re + 011 top seeded infiltration growth (Re + 011 TSIG) method was continuously sliced along the bottom to obtain samples of different thickness. The levitation force and attractive force of these samples were tested at 77 K in the zero-field-cooled (ZFC) state. It is found that as the sample thickness decreases, the levitation force decreases gradually whereas the attractive force increases. This is related to the varied ability to resist the penetration of magnetic field occasioned by varying sample thickness, which are deeply revealed by combining with the characteristics of the non-ideal type-II superconductor. Further, the levitation force exhibits a trend of slow initial change followed by rapid change, which may be attributed to the growth of the sample. Measurement of the trapped field shows that a similar distribution of trapped field at the top and bottom surfaces can be achieved by removing some materials from the bottom of the bulk. These results provide a reference for meeting the actual requirements of ReBCO bulks of different thicknesses and greatly contribute to practical designs and applications.
Diffusion dynamics in branched spherical structure
Authors: Suleiman Kheder , Zhang Xue-Lan , Liu Sheng-Na , Zheng Lian-Cun
Published: June 2022

Diffusion on a spherical surface with trapping is a common phenomenon in cell biology and porous systems. In this paper, we study the diffusion dynamics in a branched spherical structure and explore the influence of the geometry of the structure on the diffusion process. The process is a spherical movement that occurs only for a fixed radius and is interspersed with a radial motion inward and outward the sphere. Two scenarios govern the transport process in the spherical cavity: free diffusion and diffusion under external velocity. The diffusion dynamics is described by using the concepts of probability density function (PDF) and mean square displacement (MSD) by Fokker–Planck equation in a spherical coordinate system. The effects of dead ends, sphere curvature, and velocity on PDF and MSD are analyzed numerically in detail. We find a transient non-Gaussian distribution and sub-diffusion regime governing the angular dynamics. The results show that the diffusion dynamics strengthens as the curvature of the spherical surface increases and an external force is exerted in the same direction of the motion.
Biased random walk with restart for essential proteins prediction
Authors: Lu Pengli , Chen Yuntian , Zhang Teng , Liao Yonggang
Published: June 2022

Predicting essential proteins is crucial for discovering the process of cellular organization and viability. We propose biased random walk with restart algorithm for essential proteins prediction, called BRWR. Firstly, the common process of practice walk often sets the probability of particles transferring to adjacent nodes to be equal, neglecting the influence of the similarity structure on the transition probability. To address this problem, we redefine a novel transition probability matrix by integrating the gene express similarity and subcellular location similarity. The particles can obtain biased transferring probabilities to perform random walk so as to further exploit biological properties embedded in the network structure. Secondly, we use gene ontology (GO) terms score and subcellular score to calculate the initial probability vector of the random walk with restart. Finally, when the biased random walk with restart process reaches steady state, the protein importance score is obtained. In order to demonstrate superiority of BRWR, we conduct experiments on the YHQ, BioGRID, Krogan and Gavin PPI networks. The results show that the method BRWR is superior to other state-of-the-art methods in essential proteins recognition performance. Especially, compared with the contrast methods, the improvements of BRWR in terms of the ACC results range in 1.4%–5.7%, 1.3%–11.9%, 2.4%–8.8%, and 0.8%–14.2%, respectively. Therefore, BRWR is effective and reasonable.
Riemann–Hilbert approach and N double-pole solutions for a nonlinear Schrödinger-type equation
Authors: Zhang Guofei , He Jingsong , Cheng Yi
Published: June 2022

We investigate the inverse scattering transform for the Schrödinger-type equation under zero boundary conditions with the Riemann–Hilbert (RH) approach. In the direct scattering process, the properties are given, such as Jost solutions, asymptotic behaviors, analyticity, the symmetries of the Jost solutions and the corresponding spectral matrix. In the inverse scattering process, the matrix RH problem is constructed for this integrable equation base on analyzing the spectral problem. Then, the reconstruction formula of potential and trace formula are also derived correspondingly. Thus, N double-pole solutions of the nonlinear Schrödinger-type equation are obtained by solving the RH problems corresponding to the reflectionless cases. Furthermore, we present a single double-pole solution by taking some parameters, and it is analyzed in detail.
EKF-based positioning study of a mobile robot with McNamee wheels
Authors: Xu Jiahui , Liu Gang , Liu Jinhao , Lv Zhiyong , Gao Song
Published: June 2022

This paper focuses on the localization of a McNamee wheel mobile robot, which has six states of motion and more complex kinematic equations than a normal mobile robot using a McNamee wheel. In this paper, the kinematic model of the McNamee wheel mobile robot is developed, and the extended Kalman filter algorithm (EKF) is used to fuse the inertial measurement unit (IMU) and the wheel encoder odometer information to estimate the position state of the mobile robot and to eliminate the environmental noise and the effect of wheel slippage. By comparing the estimated and calculated values with the actual trajectory, the proposed method is able to eliminate environmental effects and correctly reflect the posture information of the McNamee wheel mobile robot. It is demonstrated that the proposed method can eliminate the environmental influence and correctly reflect the posture information of the McNamee wheel mobile robot.