bluuebunny/crossref_metadata_2025 huggingface dataset:
E‐mobility in Slovakia by 2030—End of oil dependency?
Authors: Zábojník Stanislav , Steinhauser Dušan , Kráľ Pavol
Published: June 2022

More European countries seriously depend on oil supplies from Russia primarily via one pipeline, which makes energy security weaker. This energy balance brings a massive problem for the import intensity; therefore, e‐mobility might be a potential solution for the trade deficits of many European countries. Battery Electric Vehicles and Plug‐In Hybrid Electric vehicles have been introduced within the priorities of the EC but also by car manufacturing companies worldwide. By 2050, massive growth of Electric vehicles (EVs) is expected, and significant changes in favour of electric cars have to be observed in new car sales till 2030. The article's main objective is to investigate whether and to what extent new sales of e‐cars bring lower oil imports to Slovakia. The authors use three scenarios (based on regression models) differentiating market force intensity and regulation stringency till 2030. The significant findings of the models provide an estimated number of EVs on Slovak roads in 2030 and significant oil import cuts stemming from oil import substitution. The conclusion suggests that by 2030, Slovak oil imports will only slightly decrease due to e‐mobility penetration, even in the most optimistic scenario.
Hybrid protection algorithm for power system with renewable energy generation using Stockwell transform and Wigner distribution function
Authors: Mahela Om Prakash , Gupta Mukesh Kumar , Kulshrestha Atul , Khan Baseem , Mahla Rajendra , Garg Akhil Ranjan , Gautam Aditya R. , Padmanaban Sanjeevikumar
Published: June 2022

Rapid technological development in grid integration of renewable energy (RE) plants has increased the RE penetration level in power utility network. This dramatic change in power scenario challenges the protection and stability of grid. Therefore, this work proposed a protection scheme algorithm (PSA) for the RE integrated hybrid power system. This PSA is implemented in the following steps: (1) calculate Wigner distribution function powered fault index (WFI), (2) calculate Stockwell transform powered combined FI (SCFI), (3) calculate hybrid FI (HFI) using WFI and SCFI, (4) classify the faults using number of faulty phases and fault ground index. Proposed hybrid fault index is used for the identification of faults. It also considers the change in magnitude and waveform distortions of current signals. The proposed PSA effectively identifies and classifies the faulty events such as single phase to ground, two phase, two phase to ground and all phases to ground. PSA is successfully tested for the recognition of faults under various operating scenarios like noisy scenario, different magnitudes of fault impedance, fault location node and fault incidence angle, lines comprising of overhead section and underground cable with availability of transformer. This PSA is effective to discriminate the operational switching events compared to faulty events. It is concluded that performance of the introduced PSA is better and fault detection time is less compared to wavelet energy spectrum entropy based PSA, discrete wavelet transform (DWT) based PSA and Stockwell transform supported PSA.
Various methods of circular interpolation performance analysis
Authors: Císar Miroslav , Tlach Vladimír , Zajačko Ivan
Published: June 2022

The paper discusses the possibilities and methodology of utilizing software, designed to be used with a double ball bar device to analyze CNC machine tool positioning performance, to analyze measurements measured by a different method. The Renishaw Ballbar system is a special tool designed to allow rapid and highly effective checks of positioning performance of any numerically controlled cartesian structure, such as a CNC machine tool, and at the same time allows monitoring its condition and to some extent predict its future development. The system uses sophisticated algorithms to decompose the overall measured inaccuracy of examined machine to values of individual errors and offers possible actions to remove such errors. The ability to push different measurements of circularity, such as measurement of circularity of machined surface on a coordinate measuring machine, would allow checking the presence of various errors without the necessity to measure with a double ball bar device. Therefore, the paper presents the custom software, that shows such possibilities, which was developed at the Department of Automation and Production Systems, Faculty of Mechanical Engineering, University of Zilina.
Influence of pressure on the change of temperature inside the elastic element under dynamic stress
Authors: Krajňák Jozef , Grega Robert , Puškár Michal
Published: June 2022

The article describes the change in temperature inside the elastic element when the pressure changes. These flexible elements are used in flexible pneumatic couplings developed at our workplace and are pressurized by a certain value of pressure depending on the transmitted torque. We test the given elements on a test rig designed at our workplace. It describes this device in detail in this article. On this device we test these elastic elements at different pressures. We find out how much influence the pressure value in the elastic element has on the change of temperature inside the element. We will find out whether the change in pressure also has a significant effect on the change in temperature and whether this temperature also affects the functionality of the device in which these elements are used.
Mass Minimizing of Truss and Beam Structures Subjected to Cumulative Fatigue Damage
Authors: Vaško Milan , Jakubovičová Lenka , Sága Milan , Ságová Zuzana , Kuric Ivan , Handrik Marian , Kopas Peter
Published: June 2022

The work presents the methods and solutions of the optimizing design of the truss and beam structures subjected to the cumulative fatigue damage. Two basic approaches used in the optimization of mechanical systems are presented in the paper - the so-called direct search methods and the gradient methods. A short comparative and gradient approach was made. The aim was to minimize the weight of the truss or beam structure with restrictions affecting the prescribed fatigue life. The computational model assumed only quasi-static loading with different number of cycles.
Development of a Computational Model of Lattice Structure
Authors: Raž Karel , Chval Zdeněk , Santos Raflem
Published: June 2022

This paper deals with the description of the mechanical properties of the plastic lattice structure. These structures are nowadays used in the additive manufacturing. The final goal was to found a mathematical formula, which allowed the FEM simulation of the described lattice structures as the structure were a solid material. The formula stablishes relationship between the original material Young Modulus and weight ratio of the lattice cell. Validation of the formula was performed by the mechanical test. The basis of the study was real testing and measurement, analysis of simulation using the finite element method and the Gibson-Ashby model with some enhancements to get to results within 95% of reliability.
Numerical Simulation of Tram Collision with Pedestrian
Authors: Spirk Stanislav , Spicka Jan , Vychytil Jan
Published: June 2022

This paper is focused on the field of traffic passive safety. The main point of this research is to reduce the severity of the consequences of a collision between tramway and pedestrian. The collision scenario is based on statistical data of local research in Czech Republic. For the first assessment of influence of tram geometry, it is necessary to investigate in the numerical simulations with different shapes of tram face. For this purpose the Multibody simulations are carried. Then the detail finite element simulations are prepared. The explicit finite element code Virtual Performance solution (VPS) and human body model Virthuman where used for the simulations. The approval process and standards were prepared for trams in last years (e.g Technical Guide Tramway front-end design) and already today it is visible significant contrast with automotive industry. The main complications in design process are connected with other requirements for tram front-end construction. These requirements are from other passive and active safety field (requirement for collision tram-tram, collision tram-road vehicle, active safety eg. visibility) and from another fields (durability, design, aerodynamics). The new construction safe for pedestrian is different in more ways. Therefore it is difficult to propagate the changes in construction.
Determination of the operational parameters values for Airbus A300-600ST Beluga aircraft on the basis of CFD tests
Authors: Nowacki Marcin , Olejniczak Damian
Published: June 2022

The article presents a method for estimating the values of basic operational and aerodynamic parameters of an aircraft. It contains a multistage analysis of CFD test results for the Beluga Airbus A300-600ST model. The first step of the method is to determine the values of aerodynamic parameters such as lift coefficient, drag coefficient, lift force and drag force in specific flight conditions. A comparative analysis of the coefficients of lift and drag force depending on the angle of attack of the aircraft allowed the estimation of the optimal angle of attack of the Airbus A300-600ST Beluga. In the next step, the operational values and the maximum flight ceiling of the aircraft were determined. For this purpose, the results of CFD simulation tests for the optimal angle of attack of the aircraft were used. This article allowed determining the characteristics of the components of aerodynamic force of an airplane depending on the angle of attack, flight altitude and flight speed, determining the optimal angle of attack of the aircraft and calculation of the optimal and maximum flight ceiling values of the Airbus A300-600ST Beluga.
Computer-aided Eco-design Grinding Machines using Software SolidWorks Sustainability
Authors: Bałdowska-Witos Patrycja , Macko Marek , Łączny Daniel , Kruszelnicka Weronika , Lewandowski Jakub
Published: June 2022

The publication presents selected results of an attempt to link material and environmental valuation with the design of technical objects in accordance with the requirements of the concept of Life Cycle Management. The goal of this action was to develop environmental analysis of the conical shredder using the SolidWorks Sustainability application. The assessment of environmental impacts included: extraction of raw materials, material processing, production of parts, assembly, use of the product, landfill storage and transport. Based on the results of the analysis, the potential emission levels were determined: CO2, SO2, PO4 and guidelines for the environmental development of technical facilities were proposed.
Conceptual Design and Simulation of Cable-driven Parallel Robot for Inspection and Monitoring Tasks
Authors: Bartoš Michal , Bulej Vladimír , Kuric Ivan
Published: June 2022

The paper deals with the conceptual design of cable-driven parallel robot which will be used for inspection and monitoring tasks in production process. The reason and need of vision based control of the production process is described in the introduction. Furthermore, mechanisms with parallel kinematic structure are described, as well as their usage in industry and sports broadcasts. On that basis, there is proposed the conceptual design of the cable driven parallel robot (CDPR) for desired task of visual monitoring of production line. Finally, there is proposed a simulation of designed robotic system and workspace shape analysis.
Model Identifying the Airfoilicing Process Beginning on the Basis of Aircraft Flight Parameters
Authors: Olejniczak Damian , Nowacki Marcin
Published: June 2022

Aircraft icing is the process of changing the state of concentration of water contained in the air in the form of steam into a solid form accumulating on the surface of aircraft construction elements during a flight or results from the direct accumulating of ice crystals on the aircraft surface. The process of aircraft icing is complex and depends on many variable factors related to atmospheric conditions and aircraft flight parameters. The goal of work is to develop a deterministic model for identifying the beginning of the icing process depending on the aircraft flight parameters on the basis of CFD simulations.
Kinematics Analyses of the Spatial Mechanism Using Matlab
Authors: Sapietová Alžbeta , Žmindák Milan , Dekýš Vladimír , Štalmach Ondrej , Sapieta Milan
Published: June 2022

The aim of this paper is to present a method of computer formulation and solution of equations of kinematics of spatial mechanical systems. The method of the vector closed loop is generally known way how to built the constraint equations. This method is recommended for planar kinematics. This paper shows the way how to take advantage of the vector cross product, vector magnitude and scalar product of two vectors for getting the constraint equations for spatial mechanism.
Modelling and Numerical Analysis of De-Icing Sprinkler-Flusher Airport Machine Arms
Authors: Dobrowolski Damian , Piekarska Wiesława , Superczyńska Paulina , Stępień Sławomir
Published: June 2022

Modern and innovative de-icing sprinkler-flusher airport machines are now equipped with special arm system. The vehicle arms are manufactured for removal of ice or frost from the surfaces of the airports runways and areas by pouring designated for that chemicals substances. The paper presents a study of the performance of airport de-icing vehicle’s arms, establishes numerical simulation model of the arm system by three-dimensional software and finite element analysis software. Based on the numerical modelling and analysis, the work focuses on study of the strength and stiffness of airport de-icing vehicle’s arm and researched the distribution of stress and deformation under the most dangerous condition. The results show that designed double-arm system can be optimized and manufactured from different, light materials and shows dangerous displacement concentration areas of the arm structure. It has important guiding significance to the optimization and manufacturing production of the arm structure.
Simulation of Active Wheelset Steering for an Electric Locomotive
Authors: Kalivoda Jan
Published: June 2022

Reduction of the force interaction between vehicle and track is strongly desirable for many reasons. Because conventional methods of reduction of wheel-rail contact forces, based on tuning of vehicle suspension parameters or utilising various mechanisms acting between wheelsets, bogie-frames and car-body, reach their limits, active controlled systems are becoming a promising solution of the problem. The paper is created within the project which aim is to design a system of active wheelset steering for an electric four-axle locomotive. The project consists of three main stages: multibody simulations, scaled roller rig experiments and field tests. One of the important elements of wheelset steering system is the estimation of the actual track curvature. The paper focuses on the track curvature calculation based on the rotation of the bogies towards the bogie-frame. The method of track curvature calculation is proposed and assessed across varying track radiuses, vehicle speeds and friction conditions.
Lower limb models used for biomechanical analysis of human walking
Authors: Molina Ludwin , Iwaniec Marek
Published: June 2022

Over time, many researchers have focused on creating models to mathematically represent movements performed by human lower limbs, such as walking, running, and jumping. These models provide a non-invasive method to estimate kinematic and kinetic parameters under different conditions. This article reviews the main lower limb models used to study human walking and compares their performance with a 3D model consisting of seven links created using the simulation environment Simscape Multibody. A description of each model is presented, highlighting its main characteristics and the assumptions that led to its formulation. We execute numerical simulations based on the first-order Euler method to solve the differential equations resulting from the models’ implementation.
Influence of Machining Conditions on Friction in Abrasive Flow Machining Process – A Review
Authors: Nowacka Agnieszka , Klepka Tomasz
Published: June 2022

This paper presents a rage of variable machining factors which influence substantially friction directly or by the abrasive media wear developed in the cutting zone. Abrasive flow machining is method of machining surfaces of complex holes and curved surface. In the case of traditional stream treatment methods abrasive (AFM) it is difficult to obtain a uniform roughness radial decomposition during polishing complicated openings, which results from uneven distribution of abrasive forces. The group of direct factors include the work piece materials and abrasive media, changes in the fluid pressure, number of flow cycles, the medium flow frequency. In addition, it was proposed modifications in the amount and size of grains abrasives filling the abrasive medium to increase the value of the grain pressure force on the surface to be processed and obtained an even surface of complex holes in the process AFM processing. Special attention was paid to the abrasive media wear evolution and its pronounced effect on changes of the contact conditions. The experiment results also confirm that the rise in the medium flow frequency during the process will not affect the roughness changes work piece surface.
A Flexible Mechanism Based Vibration Isolator for Machine Tool Application
Authors: Vijay Satpute Nitin , Iwaniec Marek
Published: June 2022

The paper presents novel design of vibration absorber with innovative features including use of flexible link based mechanism at the interface of tool holder and cutting tool. The mechanism ensures modification of the dynamic force interaction at the damping element and results in lower force transmissibility. It ensures amplification of the relative velocity at the damping element, which results in significant reduction of the damping element mass used for energy dissipation. The presented absorber has advantages of passive and economical operation in comparison to the active and semi-active solutions. Further, the proposed solution results in up to 53% reduction in the force transmissibility. A real size design has been presented for frequency range of 0-1100 Hz and maximum force amplitude of 700 N. Numerical simulations have been performed with consideration of flexible joint and structural element dynamics. Simulation results with FEA and PRBM approach have been compared with detailed analysis of the important design parameters.
Intelligent System Supporting Technological Process Planning for Machining
Authors: Rojek Izabela , Mikołajewski Dariusz , Kotlarz Piotr , Macko Marek , Kopowski Jakub
Published: June 2022

The aim of the study was to develop a system supporting technological process planning, the functioning of which would resemble the way human experts act in their fields of expertise, one capable of gathering necessary knowledge, analysing data, and drawing conclusions to solve problems. This could be done by utilising artificial intelligence (AI) methods available within such systems. The study proved the usefulness of AI methods, and their significant effectiveness in supporting technological process planning. Technological-process planning based on an expert system is divided into the following stages: the selection of the semi-finished products; the establishing of the technological process structure, and the selection of the workpiece instrumentation, machine tools, tools, and tooling and machining parameters for each technological operation. The system-embedded knowledge takes the form of neural networks, decision trees and facts. The system is presented using the example of a real enterprise. The intelligent expert system is dedicated to process engineers who have not yet gathered sufficient experience in technological-process planning, or who have just begun their work in a given production enterprise, and are not very familiar with its machinery and other means of production.
Assumptions for Modeling of the Hot Plate Welding Process Considering the Automatic Welding Machine Design
Authors: Wałęsa Krzysztof , Biszczanik Aleksandra , Malujda Ireneusz , Wilczyński Dominik
Published: June 2022

Drive and conveyor belts are widely used in processing and mining industries. One of their types, which are often used in light-duty applications, are the belts with round cross-section and several millimeters in diameter. They are often made of thermoplastic elastomers, in particular ofweldable polyurethane. Their production process requires to carry out the operation of joining the belt ends to obtain a closed loop. This operation is often carried out by means of butt welding utilizing the hot plate method. This process is often performed by hand using simple tools. Authors took an effort to design the automatic welding machine, which can make durable joints of this type automatically. The design works comprise control system configuration which calls for identifying the technological parameters of the process, being the reason for undertaking the research works on the hot plate welding process. The main aim of this activity was to formulate of the mathematical model of the hot plate welding of round drive belts which is necessary to identify the process parameters and the correlations between them. In the paper, the assumptions for the hot plate welding process modeling were presented. During their formulating, technical conditions were taken into consideration resulting from some of the characteristics observed in an automatic welding device prototype which had been implemented for industry production.
Effect of Vibration on Machine Tool Accuracy and Lifetime
Authors: Gavlas Martin , Drbul Mário , Dekys Vladimir , Saga Milan
Published: June 2022

The article deals with the influence of vibrations for the accuracy and durability of machine tools. Main content involves the use of technical diagnostics, which includes vibrodiagnostics. Vibrodiagnostics is applied directly in the technological manufacturing process. Technological manufacturing process of machining is the rough grinding of steel balls. Using vibrodiagnostics, information is recorded, which are further evaluated. The evaluation of the obtained information has several parts. The first part deals with the influence of vibrations on the service life of the machine assembly. And it examines the current state of the machine. The second part consists of from finding a connection between the vibrations and the workpiece. Several geometric measurements of the samples were used to find the connection, for example primary profile, undulation surface, profile amplitude and other are compared with the recorded vibrations.
Evaluation of Geometric Occlusal Conditions Based on the Image Analysis of Dental Plaster Models
Authors: Grochala Dominik , Paleczek Anna , Lemejda Justyna , Kajor Marcin , Iwaniec Marek
Published: June 2022

It has been proved that dimensions of the dental arch may change as a result of growth or orthodontic treatment. The most intense transformations can be observed at young age during an occurrence of a mixed dentition period. Based on diagnostic models in a form of plaster casts there is a possibility to measure following features: overbite, overjet, the curve of Spee, arch depth, arch width and Bolton’s ratios. Nowadays computer-aided tools can provide valuable information for dentists or orthodontists and simplify analysis, diagnosis and preparation of a treatment plan. Correct organization of the dental arch in the horizontal plane can be modelled as a parabola for a mandible and as a section of the ellipse for a jaw. A developed system based on the Python programming language provides automated analysis of plaster model images. Proposed methodology includes preprocessing of provided casts’ pictures and segmentation of dental arch using methods such as image morphological operations, edge detection and active contour algorithm. In this research there were also calculated semi-ellipse and parabola fitting functions of dental arches and measured the root mean squared error relative to the original curves. Preliminary results showed 1.29 mm RMSE level for correct occlusion and 2.39 mm in case of malocclusion. Proposed methods can be used for simplifying the analysis of dental arches’ shape and monitoring of changes during orthodontic treatment.
The Use of Simulation Software using the Discrete Element Method (DEM) for the Process of Materials Comminution
Authors: Kruszelnicka Weronika , Macko Marek , Łączny Daniel , Bałdowska-Witos Patrycja , Lewandowski Jakub
Published: June 2022

Comminution processes are one of the most common processes for processing energy materials, e.g. coal, biomass, and post-recycling elements. The hitherto unsolved problem is the high energy consumption of machines and the lack of precise descriptions of the phenomenon of comminution in terms of the relationship between the design features of mills and the properties of comminuted materials. The dynamic development of simulation techniques based on advanced models and the method of discrete elements allows for a certain mapping of occurring phenomena. The purpose of the work is to illustrate the possibility of using simulation software based on the discrete element method to model the grinding processes in the shredders grinding assemblies. The paper presents aspects of modeling the shape and size of particles, their interactions and contacts with mills structural elements, as well as aspects of crushing modeling in RockyDem software.
Design and Construction of an Innovative Particle Analyser
Authors: Łączny Daniel , Lewandowski Jakub , Kruszelnicka Weronika , Bałdowska-Witos Patrycja , Moraczewski Krzysztof
Published: June 2022

The paper presents issues concerning the implementation of particle size analyzers in the evaluation of the grinding product. A review of the current solutions of the analyzers used in practice was made. The usefulness of the original size analysis system according to its own design has been verified and exemplary results of the size assessment of grinding products - polymeric materials and biological materials have been presented.
The Algebraic Model of the Dry Ice Extrusion Process in a Die with a Conical-Cylindrical Channel
Authors: Górecki Jan
Published: June 2022

The article presents the results of works on formulating an algebraic model of crystallized CO2 extrusion process in a convergent circular–symmetrical channel. The paper presents the method of derivation of the model as well as preliminary comparison of the influence of variance of the 3 geometrical parameters describing the shape of the forming channel. Based on the results of the performed analysis, conclusions are formulated to determine the basis and future direction of study to the development of single-channel dies allowing to extrude dry ice with effective compacting stress values.
Pediatric Tacrolimus-Induced Reversible Cerebral Vasoconstriction Syndrome after Heart Transplantation
Authors: Shabo Leah , Ishaque Mariam , Sarathy Danyas , Kumar Jeyan , Xixis Kathryn , Park Min
Published: June 2022

Reversible cerebral vasoconstriction syndrome (RCVS) is a rare post-organ transplantation complication. While uncommon, complications of post-transplant RCVS can be devastating, with sequelae including ischemic or hemorrhagic stroke and potential significant neurological morbidity. There is a paucity of literature on tacrolimus-mediated RCVS, particularly in the pediatric population. To date, only five case reports have been published, with the youngest patient being 15 years of age. We report the youngest case to date of post-heart transplant tacrolimus-induced RCVS in a 6-year-old male. The present case highlights the necessity of urgent imaging in suspected cases of RCVS, the potential diagnostic challenges surrounding the etiology of headache, the benefits of treating underlying cerebral vasospasm, and the importance of rapid discontinuation of the offending agent for the remission of symptoms and prevention of long-term sequelae.
Vapocoolant Spray for Pain Control in Intramuscular Injection Applications: A Prospective, Randomized Controlled Trial
Authors: Bedel Cihan , Selvi Fatih , Akçimen Mehmet
Published: June 2022

Background Many pharmacological and nonpharmacological methods have been investigated along with advances in pain treatment. One of these nonpharmacological methods is the use of vapocoolant spray.

Objective This study aimedto demonstrate the effectiveness of vapocoolant spray to reduce pain during intramuscular (IM) injection.

Patients and Methods The study included ≥18 years old patients admitted to the emergency department who were asked to undergo IM injection. Patients were randomly divided into two groups as vapocoolant spray and control group. Demographic data, injection side, and visual analog scale (VAS) of the patients were recorded.

Results Mean VAS values during IM injection were significantly lower in patients treated with vapocoolant spray compared with the control group. The severity of pain during IM injection was lower in the vapocoolant spray group as both moderate pain (VAS > 3 cm) and severe pain (VAS > 5.4 cm) compared with the control group.

Conclusion Vapocoolant spray to be applied before IM injection is effective in reducing pain caused by the injection.
“It Broke My Heart When They Ripped the Old Logo Off the Wall”: Places, Uses and Meanings of the Rebranded Logo
Authors: Erjansola Ari-Matti , Virtanen Linda , Lipponen Jukka
Published: June 2022

Many authors recognize the links between brand logos and identity, but aside from being mere symbols of the organizations that they represent, brand logos are also physical objects with a location and context in which they are interpreted. In this article, we analyze the logo as a physical artifact in relation to its place and physical surroundings in a Finnish university merger. We utilize longitudinal survey data from 140 respondents, and through thematic analysis, we show how employees interpret the logo and its meaning in relation to place and how day-to-day use and management actions affect its interpretation. We argue that logos should be addressed as physical artifacts that can function as identity markers at the organizational level and a mere change of visual elements can, therefore, profoundly alter the sense and identity of a place. This study enhances understanding of brand logos in relation to place and emphasizes their significance during organizational change.
Third time is the charm: Ternary organic solar cells improve efficiency and stability
Authors: Piccone Ashley
Published: June 2022

Charge and energy transfer processes in organic solar cells with three components
Stability of the Poincaré maps for a stochastic fast–slow system
Authors: Yang Min , Chen Guanggan
Published: June 2022

This work focuses on the existence and the stability of Poincaré maps of a stochastic fast–slow system with multiplicative noise. It shows that the Poincaré maps of the stochastic fast–slow system return, one time or even infinite times, to a small neighborhood of a fixed point of the Poincaré map for a deterministic fast–slow system, which implies the stability of Poincaré maps of the stochastic fast–slow system with the small noise disturbing.
Ion-induced charge emission from unpolished surfaces bombarded by an [Emim][BF4] electrospray plume
Authors: Klosterman Matthew R. , Rovey Joshua L. , Levin Deborah A.
Published: June 2022

Experiments were conducted at the University of Illinois at Urbana Champaign Electric Propulsion Laboratory to study the ion-induced secondary charge emission from surfaces bombarded by an [Emim][BF4] electrospray plume. The surfaces were unpolished and had oxide and hydrocarbon layers typical of as-received materials used in electrospray experiments. The effect of changing the bias from −85 to +85 V on the target collecting current from the electrospray plume was measured. These data are used to calculate the yield of positive and negative charged species emission from the target due to bombarding cations and anions. The yields of positive charges per incident cation (γcation+), negative charges per incident cation (γcation−), positive charges per incident anion (γanion+), and negative charges per incident anion (γanion−) are measured for eight different industrial materials commonly used in electrospray diagnostics or thruster and spacecraft construction. These yields range from 0 to 1.3 charges per incident ion over a range of emitter voltages from 1.5 to 2.9 kV and largely display linearly increasing trends with increasing emitter voltage. Over this emitter voltage range, γcation+ ranges from 0 to 0.55, γcation− ranges from 0 to 0.75, γanion+ ranges from 0 to 0.4, and γanion− ranges from 0.3 to 1.3. The data show for the first time positive and negative charges being emitted due to both cation and anion bombardment and suggest that secondary ions sputtered from the surface are important to the secondary charge emission behavior in electrospray plumes.
Equilibrium points in restricted problems on S2 and H2
Authors: Sánchez-Cerritos Juan Manuel , Ding Liang , Wei Jinlong
Published: June 2022

In this paper, we consider the restricted four-body problem on S2 and the restricted three-body problem on H2. In the first case, the primary particles are considered to be rotating around the vertical axis. In the latter case, the primaries move at a hyperbolic relative equilibrium. If the primary particles locate at height z0 = 0 and they form an isosceles triangle on S2, then the number of symmetric equilibrium points of the restricted four-body problem depends on the angular velocity, the configuration, and the masses of the primaries. For this case, the number of equilibrium points is 0, 2, 4, 6, or 8. If the primaries are at height z0 ∈ (0, 1), then the primaries form an equilateral triangle and the number of symmetric equilibrium points is 8, 11, 14, 17, or 20. The number depends on the position of the primaries, and it is higher than the previous case due to the higher number of symmetry axes of the triangle formed by the primaries. On the other hand, for the restricted three-body problem on H2, the number of equilibrium points is 3, considering that the primaries move at a hyperbolic relative equilibrium. We analyzed the general (non-symmetric) case, showing the locations of the equilibrium points for the given positions of the primaries. We also studied the stability of these equilibrium points.
Ultrafast scanning electron microscopy with sub-micrometer optical pump resolution
Authors: Garming Mathijs W. H. , Weppelman I. Gerward C. , Lee Martin , Stavenga Thijs , Hoogenboom Jacob P.
Published: June 2022

Ultrafast scanning electron microscopy images carrier dynamics and carrier induced surface voltages using a laser pump electron probe scheme, potentially surpassing all-optical techniques in probe resolution and surface sensitivity. Current implementations have left a four order of magnitude gap between optical pump and electron probe resolution, which particularly hampers spatial resolution in the investigation of carrier induced local surface photovoltages. Here, we present a system capable of focusing the laser using an inverted optical microscope built into an ultrafast scanning electron microscopy setup to enable high numerical aperture pulsed optical excitation in conjunction with ultrafast electron beam probing. We demonstrate an order of magnitude improvement in optical pump resolution, bringing this to sub-micrometer length scales. We further show that temporal laser pump resolution can be maintained inside the scanning electron microscope by pre-compensating dispersion induced by the components required to bring the beam into the vacuum chamber and to a tight focus. We illustrate our approach using molybdenum disulfide, a two-dimensional transition metal dichalcogenide, where we measure ultrafast carrier relaxation rates and induced negative surface potentials between different flakes selected with the scanning electron microscope as well as on defined positions within a single flake.
Understanding random telegraph noise in two-dimensional BP/ReS2 heterointerface
Authors: Lee Byung Chul , Seo Youkyung , Kim Chulmin , Kim Yeeun , Joo Min-Kyu , Kim Gyu-Tae
Published: June 2022

Black phosphorus (BP)-based broken gap heterojunctions have attracted significant attention mainly owing to its wide thickness-dependent Fermi level, offering opportunities to demonstrate various carrier transport characteristics and high performing optoelectronic applications. However, the interfacial effects on the carrier scattering mechanism of the two-dimensional (2D) broken gap heterojunctions are unclear. Herein, we discuss the origin of random telegraph noise of multilayer BP/ReS2 heterojunction diode, in particular, at the direct tunneling (DT) conduction regime. The gate-tunable diode characteristic of BP/ReS2 heterojunction allows one to unveil systematically the transition of the charge fluctuation mechanism from drift-diffusion to the DT regime. Unlike individual BP and ReS2 devices, the current noise histogram obtained from the BP/ReS2 heterojunction device exhibits exclusively two dominant peaks at the DT regime. We ascribed this distinct low-frequency noise feature representing the presence of random telegraph signal to the BP/ReS2 interfacial traps by taking into account of the inherent direct tunneling current conduction mechanism. In addition, the electrostatic bias-dependent power spectrum density manifests clearly that the dominant scattering mechanism is the carrier number fluctuation rather than tunneling barrier height fluctuation at the BP/ReS2 heterointerface. This study elucidates the carrier transport and the charge fluctuation mechanism at the 2D heterostructure interface.
Optimization of normally-off β-Ga2O3 MOSFET with high Ion and BFOM: A TCAD study
Authors: Do Huy-Binh , Phan-Gia Anh-Vu , Nguyen Van Quy , De Souza Maria Merlyne
Published: June 2022

A combination of recessed-gate and gate-field plate in lateral β-Ga2O3 metal–oxide–semiconductor field-effect transistor (MOSFET) is proposed in the Technology Computer Aided Design study to improve its ON resistance (RON) and breakdown voltage. Enhancement-mode (E-mode) is achieved by controlling the thickness of the recessed-gate. Lateral E-mode β-Ga2O3 MOSFET achieves a saturation current density near 120 mA/mm, ION/IOFF ratio ∼109, RON ∼91 Ω mm, and breakdown voltage of 1543 V. The optimized structure results in a prediction of a power figure-of-merit of 261 MW/cm2 in a horizontal E-mode β-Ga2O3 MOSFET.
Real-time changes in the AC magnetic susceptibility of reagents during immunomagnetic reduction assays
Authors: Chen Hsin-Hsien , Hsu Ming-Hung , Lee Kun-Hung , Chen Wen-Yih , Yang Shieh-Yueh
Published: June 2022

Antibody-functionalized magnetic nanoparticles dispersed in phosphate-buffered saline solution were used as reagents in immunomagnetic reduction assays. Biomolecules are detected in bioliquid samples when they associate with magnetic nanoparticles and reduce the AC magnetic susceptibility χac of the reagent at a given frequency. In this study, the chemical kinetics for the real-time χac during the association was investigated. The association kinetics between biomolecules and nanoparticles consists of diffusion and binding steps. It was found that the diffusion speeds up in samples with higher concentrations of molecules. Furthermore, the period of association was longer for samples having higher concentrations of molecules. The association rates were proportional to the T-Tau concentration. The results showed that one biomolecule was associated with one magnetic nanoparticle.
Does neuromuscular fatigue generated by trail running modify foot‐ground impact and soft tissue vibrations?
Authors: Trama Robin , Blache Yoann , Hintzy Frédérique , Rossi Jérémy , Millet Guillaume Y. , Hautier Christophe
Published: June 2022

The purpose of the study was to assess the influence of a preceding mountain ultramarathon on the impact between the foot and the ground and the resulting soft tissue vibrations (STV). Two sessions of measurements were performed on 52 trail runners, before and just after mountain trail running races of various distances (from 40 to 171 km). Triaxial accelerometers were used to quantify the foot‐ground impact (FGI) and STV of both gastrocnemius medialis (GAS) and vastus lateralis (VL) muscles during level treadmill running at 10 km·h−1. A continuous wavelet transform was used to analyze the acceleration signals in the time–frequency domain, and the maps of coefficients as well as the frequency and damping properties of STV were computed. Fatigue was assessed from isometric maximal voluntary contraction force loss of knee extensors (KE) and plantar flexors (PF) after each race. Statistical nonParametric Mapping and linear mixed models were used to compare the means between the data obtained before and after the races. FGI amplitude and GAS STV were not modified after the race, while VL STV amplitude, frequency and damping significantly decreased whatever the running distance. A significant force loss was observed for the PF (26 ± 14%) and KE (27 ± 16%), but this was not correlated to the changes observed in STV. These results might reveal a protection mechanism of the muscles, indicating that biomechanical and/or physiological adaptations may occur in mountain ultramarathons to limit STV and muscle damage of knee extensors.

Trial registration: ClinicalTrials.gov identifier: NCT04025138.
Topological resonance in graphene-like materials
Authors: Magar Krishna Rana , Oliaei Motlagh S Azar , Apalkov Vadym
Published: June 2022

In topological materials, interacting with short and strong optical pulses, electrons can accumulate a topological phase during the pulse. Such phase can compensate the dynamic phase resulting in topological resonance, which is visible as a large inter-band transfer of electron population. We study theoretically the topological resonance in materials of the gapped multilayer graphene type. We show that the resonance can be observed only in the systems with finite bandgap. For graphene monolayer the topological resonance can occur only in the field of an elliptically polarized pulse, while for graphene systems with many layers the topological resonance can be also realized in a linearly polarized pulse.
An approach to dual-energy contrast-enhanced spectral mammography (DE-CESM) using a double layer filter: dosimetric and image quality assessment
Authors: Niroshani Sachila , Nakamura Tokiko , Michiru Nikaidou , Negishi Toru
Published: June 2022

Dual-energy contrast-enhanced spectral mammography (DE-CESM) is a recently developed advanced technique in digital mammography that uses an iodinated intravenous contrast agent to assess tumor angiogenesis. The aim of this study was to investigate the diagnostic potential of DE-CESM recombined images in terms of radiation dose and image quality. A 50% fibroglandular—50% adipose, custom-made phantom with iodine inserts of 1.0 mgI cm−3, 2.0 mgI cm−3, 4.0 mgI cm−3 was used for the estimation of mean glandular dose (MGD) and the image quality. Low-energy (LE) images were acquired with the W/Rh, W/Rh + 0.01 mm Cu and W/Rh + 0.5 mm Al while high energy images (HE) are acquired with the W/Rh, W/Rh + 0.06 mm Ba, W/Rh + 0.01 mm Cu, and W/Rh + 0.03 mm Ce anode filter combinations. The total MGD was reduced up to a maximum from 1.75 mGy to 1.45 mGy by using Rh + 0.01 mm Cu double-layer filter for both LE and HE imaging of 50 mm, standard 50% fibroglandular phantom compared to Rh single-layer filter with W target. The minimum total MGD reduction (1.69 mGy) was observed when Rh + 0.5 mm Al was used for LE and Rh + 0.06 mm Ba was used for HE exposure. The image quality was comparable with the single-layer filter. The use of W/Rh + 0.01 mm Cu or W/Rh + 0.5 mm Al as target/filter combination for LE exposure and W/Rh + 0.01 mm Cu for HE exposure can reduce the additional radiation dose delivered by DE-CESM without degrading the image quality.
Global existence of weak solutions to viscoelastic phase separation part: I. Regular case
Authors: Brunk Aaron , Lukáčová-Medvid’ová Mária
Published: June 2022

We prove the existence of weak solutions to a viscoelastic phase separation problem in two space dimensions. The mathematical model consists of a Cahn–Hilliard-type equation for two-phase flows and the Peterlin–Navier–Stokes equations for viscoelastic fluids. We focus on the case of a polynomial-like potential and suitably bounded coefficient functions. Using the Lagrange–Galerkin finite element method complex behavior of solution for spinodal decomposition including transient polymeric network structures is demonstrated.
Critical sharp front for doubly nonlinear degenerate diffusion equations with time delay
Authors: Xu Tianyuan , Ji Shanming , Mei Ming , Yin Jingxue
Published: June 2022

This paper is concerned with the critical sharp travelling wave for doubly nonlinear diffusion equation with time delay, where the doubly nonlinear degenerate diffusion is defined by

(

(

u

m

)

x

p
−
2

(

u

m

)

x

)

x

with m > 0 and p > 1. The doubly nonlinear diffusion equation is proved to admit a unique sharp type travelling wave for the degenerate case m(p − 1) > 1, the so-called slow-diffusion case. This sharp travelling wave associated with the minimal wave speed c*(m, p, r) is monotonically increasing, where the minimal wave speed satisfies c*(m, p, r) < c*(m, p, 0) for any time delay r > 0. The sharp front is C
1-smooth for

1

p
−
1

<
m
<

p

p
−
1

, and piecewise smooth for

m
⩾

p

p
−
1

. Our results indicate that time delay slows down the minimal travelling wave speed for the doubly nonlinear degenerate diffusion equations. The approach adopted for proof is the phase transform method combining the variational method. The main technical issue for the proof is to overcome the obstacle caused by the doubly nonlinear degenerate diffusion.
Measurement and image-based estimation of dielectric properties of biological tissues —past, present, and future—
Authors: Sasaki Kensuke , Porter Emily , Rashed Essam A , Farrugia Lourdes , Schmid Gernot
Published: June 2022

The dielectric properties of biological tissues are fundamental pararmeters that are essential for electromagnetic modeling of the human body. The primary database of dielectric properties compiled in 1996 on the basis of dielectric measurements at frequencies from 10 Hz to 20 GHz has attracted considerable attention in the research field of human protection from non-ionizing radiation. This review summarizes findings on the dielectric properties of biological tissues at frequencies up to 1 THz since the database was developed. Although the 1996 database covered general (normal) tissues, this review also covers malignant tissues that are of interest in the research field of medical applications. An intercomparison of dielectric properties based on reported data is presented for several tissue types. Dielectric properties derived from image-based estimation techniques developed as a result of recent advances in dielectric measurement are also included. Finally, research essential for future advances in human body modeling is discussed.