bluuebunny/crossref_metadata_2025_split huggingface dataset:
Finite element simulations of rail milling based on the modified Johnson-Cook constitutive model
Authors: Liu Peijie , Quan Yanming , Wan Junjie 
Published: January 2021

Abstract
Rail milling plays an indispensable role to remove surface defects and irregularity in the railway maintenance industry. In this paper, an appropriate 2D orthogonal cutting model of rail milling process was established. Finite element simulations of rail milling were conducted in detail based on a modified Johnson-Cook constitutive model. The simulation results show that a large amount of cutting heat is generated in the tool-chip contact region, and the highest temperature of the milling insert appears somewhere on the rake face with a certain distance away from the cutting edge. With the increase of cutting thickness and milling speed, the milling temperature displays an upward trend.
The Application of Perovskite Quantum Dots in Photodetectors
Authors: XiaoYang  
Published: January 2021

Abstract
Perovskite quantum dots (PQDs) can adsorb visible light and give out fluorescence or excited electron to the surroundings. Therefore, some kinds of PQDs can be used for light detection. Due to the appropriate band gap, cesium bromide and iodide-based perovskite PQDs (i.e. CsPbX3) are especially suitable for visible light detection. Some other kinds of PQDs with different photoluminescence spectrum can be used to detect ultra-violet light or infrared light. In this paper, PQD-based photodetectors are divided into three categories: photoresistors, photodiodes and field effect transistors. Herein, the device structures, characteristics and mechanism of these three types of PQD-based photodetectors are briefly reviewed. Other applications of PQDs are also briefly introduced, including selective ion detection and organic molecular detection associated with molecular imprinted polymers.
Thermo-electro-mechanical vibration of piezoelectric nanobeams resting on a viscoelastic foundation
Authors: Zhang Dapeng , Liu Mingwei , Wang Zhixiang , Lei Yongjun 
Published: January 2021

Abstract
Taking a piezoelectric nanobeam resting on a viscoelastic foundation as the research object, the free vibration of the nanobeam are studied by considering the thermo-electro-mechanical loadings. The vibration governing equations and boundary conditions are first derived using Hamilton’s principle and then the transfer function method are applied to calculate the natural frequencies under general boundary conditions. And then the influences of nonlocal parameter and material parameters of viscoelastic foundation on the vibration characteristics are also studied in detail. The results show that both nonlocal parameter and viscoelastic foundation have significant influence on the vibration of nanobeams. The conclusions of this study could provide important theoretical basis for the research and application of nanostructures in nanosensors, nanodrivers, nanoresonators and other intelligent devices.
Dactyls and inward gripping stance for amphibious crab-like robots on sand
Authors: Graf Nicole M , Behr Alexander M , Daltorio Kathryn A 
Published: January 2021

Abstract
Sandy beaches are areas that challenge robots of all sizes, especially smaller scale robots. Sand can hinder locomotion and waves apply hydrodynamic forces which can displace, reorient, or even invert the robot. Crab-like legs and gaits are well suited for this environment and could be used as inspiration for an improved design of robots operating in this terrain. Tapered, curved feet (similar to crab dactyl shape) paired with a distributed inward gripping method are hypothesized to enable better anchoring in sand to resist hydrodynamic forces. This work demonstrates that crab-like legs can withstand vertical forces that are larger than the body weight (e.g. in submerged sand, the force required to lift the robot can be up to 138% of the robot weight). Such legs help the robot hold its place against hydrodynamic forces imparted by waves (e.g. compared to displacement of 42.7 mm with the original feet, crab-like feet reduced displacement to 1.6 mm in lab wave tests). These feet are compatible with walking on sandy and rocky terrain (tested at three speeds: slow, medium, and fast), albeit at reduced speeds from traditional feet. This work shows potential for future robots to utilize tapered and curved feet to traverse challenging surf zone terrain where biological crabs thrive.
Model coupling biomechanics and fluid dynamics for the simulation of controlled flapping flight
Authors: Colognesi Victor , Ronsse Renaud , Chatelain Philippe 
Published: January 2021

Abstract
This paper proposes a multiphysics computational framework coupling biomechanics and aerodynamics for the simulation of bird flight. It features a biomechanical model based on the anatomy of a bird, which models the bones and feathers of the wing. The aerodynamic solver relies on a vortex particle-mesh method and represents the wing through an immersed lifting line, acting as a source of vorticity in the flow. An application of the numerical tool is presented in the modeling of the flight of a northern bald ibis (Geronticus eremita). The wing kinematics are imposed based on biological observations and controllers are developed to enable stable flight in a closed loop. Their design is based on a linearized model of flapping flight dynamics. The controller solves an underdetermination in the control parameters through minimization. The tool and the controllers are used in two simulations: one where the bird has to trim itself at a given flight speed, and another where it has to accelerate from a trimmed state to another at a higher speed. The bird wake is accurately represented. It is analyzed and compared to the widespread frozen-wake assumption, highlighting phenomena that the latter cannot capture. The method also allows the computation of the aerodynamic forces experienced by the flier, either through the lifting line method or through control-volume analysis. The computed power requirements at several flight speeds exhibit an order of magnitude and dependency on velocity in agreement with the literature.
Recent advances in development of nanomedicines for multiple sclerosis diagnosis
Authors: Zhang Qin , Dai Xinghang , Zhang Hu , Zeng Yujun , Luo Kui , Li Weimin 
Published: January 2021

Abstract
Multiple sclerosis (MS) is a neurodegenerative disease with a high morbidity and disease burden. It is characterized by the loss of the myelin sheath, resulting in the disruption of neuron electrical signal transmissions and sensory and motor ability deficits. The diagnosis of MS is crucial to its management, but the diagnostic sensitivity and specificity are always a challenge. To overcome this challenge, nanomedicines have recently been employed to aid the diagnosis of MS with an improved diagnostic efficacy. Advances in nanomedicine-based contrast agents in magnetic resonance imaging scanning of MS lesions, and nanomedicine-derived sensors for detecting biomarkers in the cerebrospinal fluid biopsy, or analyzing the composition of exhaled breath gas, have demonstrated the potential of using nanomedicines in the accurate diagnosis of MS. This review aims to provide an overview of recent advances in the application of nanomedicines for the diagnosis of MS and concludes with perspectives of using nanomedicines for the development of safe and effective MS diagnostic nanotools.
Previous Atlantic Multidecadal Oscillation (AMO) modulates the lightning-ignited fire regime in the boreal forest of Northeast China
Authors: Gao Cong , Zhao Fengjun , Shi Chunming , Liu Kezhen , Wu Xiaoxu , Wu Guocan , Liang Ying , Shu Lifu 
Published: January 2021

Abstract
Lightning-ignited fire is sensitive to climatic change and responsible for large fires in boreal forests. In addition to global-warming caused fire increase, large-scale climate oscillations have significantly contributed to fire variability. However, the leading climate oscillation driving lightning-ignited fire and the mechanisms connecting regional and large-scale climate in the boreal forest of Northeast China, the most fire-prone biome of China, are still unclear. By compositing fire, climate, and atmospheric data, we found that the previous Atlantic Multidecadal Oscillation (AMO) was significantly coherent with the May to August temperature–evapotranspiration variability and lightning-ignited fire occurrence. These connections were valid at both the interannual and multidecadal time scales. Different from previous viewpoints, we found no connection of fire occurrence with the El Niño-Southern Oscillation and Pacific Decadal Oscillation. A warm AMO was followed by high sea level pressure and geopotential height over the study region. We assume these atmospheric anomalies are associated with descending atmospheric motion, producing adiabatic warming and less precipitation on the land surface, both of which favour high fuel aridity and lightning ignition. Therefore, we believe that the winter AMO could be a promising predictor for lightning-ignited fire occurrences in the following summer.
Nullspaces of entanglement breaking channels and applications
Authors: Kribs David W , Levick Jeremy , Olfert Katrina , Pereira Rajesh , Rahaman Mizanur 
Published: January 2021

Abstract
Quantum entanglement breaking channels are a fundamental class of quantum operations; originally investigated for quantum information theoretic reasons, their study has since grown to touch on many aspects of quantum information science. Here we investigate the nullspace structures of entanglement breaking channels and we derive a pair of related applications. We show that every operator space of trace zero matrices is the nullspace of an entanglement breaking channel. We derive a test for mixed unitarity of quantum channels based on complementary channel behaviour and entanglement breaking channel nullspaces. We identify conditions that guarantee the existence of private algebras for certain classes of entanglement breaking channels.
Design and closed-loop control of a piezoelectric actuator
Authors: Rusu C , Besoiu S , Tatar M O 
Published: January 2021

Abstract
Piezoelectric elements can produce a high displacement resolution with high force outputs but exhibits large hysteresis nonlinearities. An efficient way to compensate for nonlinearities is using a closed loop control technique. Another limitation for many applications is their relatively short displacement ranges. One method to avoid the above-mentioned shortcoming is to integrate a piezoelectric element with a mechanical displacement amplifier based on a compliant mechanism. This paper presents the design and closed-loop control of such a piezoelectric actuator. Using the integrated strain gauge sensors, a PI controller was designed and tested.
Manufacturing of SiO2-ZnO materials with optical properties
Authors: Mocioiu O C , Băilă D I , Atkinson I , Brătan V , Mocioiu A M 
Published: January 2021

Abstract
Antireflection coatings have been widely used to increase the absorption of solar collectors and to reduce surface reflection. Many techniques have been explored to prepare thin coatings, such as sputtering, chemical etching, chemical vapour deposition, and sol-gel method. SiO2-ZnO coatings were prepared on the surface of glass substrates via the sol-gel dip-coating process. The structural, morphological and optical properties of the coatings were characterized. The vitreous structure was identified by infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Morphology of materials was observed by scanning electron microscopy (SEM). The reflectance spectra were investigated and the optical performance of the structure was determined.
The role of the friction process in abrasive grain micro cutting technology
Authors: Mazuru S , Scaticailov S 
Published: January 2021

Abstract
The process of micro-cutting with abrasive grain - complicated tribological phenomenon. The removal of the chip-shaped material from the surface of the semi-finished product is accompanied by elastic and plastic deformations of the surface, with heat releases and phase changes. One of the features of the grinding process and other types of abrasive processing, is that the removal of the chip especially takes place with negative front angles. According to [1] the average value of the front cutting angle values is within the limits -(46.6… 56.9). To the geometric parameters of the distant layer that characterizes the cutting process can be attributed: the thickness and width of the cut and the shrinkage of the chip. A series of scientific and manual works on cutting materials can be objected to the fact that in the process of deformation at cutting which is characterized by the coefficient of shrinkage of the chip a physical-mechanical influence has the characteristic of the processed material, the value of advance, depth of cutting and other parameters.
FEM simulation of C45 steel and Cu-ETP billet shaping at hot upsetting between convex conical dies
Authors: Kukhar V V , Yu Balalayeva E , Korenko M G , Prysiazhnyi A H , Anishchenko O S 
Published: January 2021

Abstract
On the basis of finite element analysis (FEA), geometric differences in the shaping during hot upsetting of cylindrical billets with a height-to-diameter ratio of 1.0 and 2.0 made of C45 (1.0503) steel and copper (Cu-ETP) between pointed convex conical dies with a cone slant angle of 12.5°, 15.0° and 17.5° are considered. The stroke velocity of the upper die is 0.5 m/s; process temperature (t) and accepted surface friction coefficient (|&#x03BC;): for steel - t = 1100 °C, &#x03BC; = 0.32, for copper - t = 850 °C, &#x03BC; = 0.34. An equation is obtained for the relation between values of reduction in height ratio and engineering strain on height of workpiece during upsetting between conical dies, taking into account the initial billet dimensions and unevenness of forming due to the geometry of tool. The presence of qualitative and quantitative differences in shaping along the height of upset steel and copper billets was revealed, i.e. influence on unevenness of forming the rheological properties of materials under process conditions. It is advisable to use the results obtained to design and improve of technological processes of open die and closed die forging with preforming of billets.
Study on grinding mode effect on external conical thread quality
Authors: Ya Ropyak L , Vytvytskyi V S , Velychkovych A S , Pryhorovska T O , Shovkoplias M V 
Published: January 2021

Abstract
The article has grounded the necessity to develop an empirical power dependence of cutting modes influence on part surface roughness obtained during thread grinding. The calculations were carried out for grinding of parts made of steel and hard alloy. There have been developed a relation of part material properties, grinding wheel options, lubricating and cooling liquid (constant for concrete conditions of thread grinding), depth of cutting (thickness of a grinded layer per path), revolutions of a part and a wheel, longitudinal feed refer to obtained roughness. It has been stated that components of the grinding mode contribute in roughness values in different way, in particular they are arranged in the ascending order as follows: grinding depth, rotation speed, and detail’s diameter.
Research of fuzzy logic application on surfaces roughness prediction under finishing milling process
Authors: Ghencea D. P. , Anania F. D. , Zapciu M. 
Published: January 2021

Abstract
Artificial intelligence systems are usefully tools for estimation of different parameters for industrial and non-industrial applications. In this paper is presented a fuzzy logic application for surface roughness prediction for two material type for a CAM milling process. A minimum number of measurements have been made on a specific material (Al 6061) and were used for prediction of a roughness of another material (Al 7075). The link parameters between these materials, used in Fuzzy logic system, is the Rockwell hardness. In this way many correction parameters of cutting regime can be calculated in a short time with minimum resource (less experiments and tests needed).
Correlation between market segmentation, industrial product features and context in design assessment
Authors: Craciun A E 
Published: January 2021

Abstract
When referring to product design assessment, even with a standard evaluation format, the perspective from which the criteria are approached differs strongly from one market category to another, this having a direct impact on the accuracy of the method. In order to achieve an objective assessment, the product must relate to a frame of reference in accordance with the product’s destination, taking into account the user specifications and the actual experience of use. This paper represents the study of correlations between the market segment, product features and context and their degree of interdependence. Thus, analysing the relations between sections, the representative influence formulas for each considered feature were deduced, highlighting the extent to which the user’s typology and context relate to the product features.
A brief review of the methods and techniques used in the innovative internal logistics processes and systems
Authors: Pascu I G , Neacsu G C , Nitu E L , Gavriluta A C 
Published: January 2021

Abstract
In the last period, logistics knew a strong technological evolution that has changed the way it operates and determined its transformation into innovative logistics, especially in the case of internal logistics. Innovation in internal logistics processes and systems consists in the use of different Industry 4.0 and digitization technologies. So, it is necessary to use modern methods and techniques to support the transformation of internal logistics processes and systems into innovative ones. This paper presents an analysis of recent studies, briefly presenting the evolution of the concept of logistics, the concepts of process and logistics system and Industry 4.0. Also, the most common methods and techniques used in the realization of innovative internal logistics systems are presented and some conclusions are presented regarding their use.
New design of precise deployable reflector. Technologies for manufacturing of physical model
Authors: Bujakas V I , Glotov M D 
Published: January 2021

Abstract
The new design of petal space antenna is considered in the paper. Various versions of solid petal-type mirrors have been considered and investigated in a number of articles and space projects. The classical scheme of petal type deployable space reflector was proposed and developed by Dornier Corporation within FIRST space project and was used in the Radioastron project to create a 10-meter antenna of space radio telescope. However, the classical petal mirror design has two significant drawbacks. Firstly, in the open state, the petals are cantilevered on the central mirror, what leads to low rigidity of the structure in open state. Secondly, in the classical design, the accuracy of the reflecting surface of the open mirror strongly depends on small errors in the operation of the deployment system. To overcome these drawbacks a new design of petal type mirror and a new system for precise opening of the mirror were proposed and studied. To test a new technical solution, a physical model of a deployable reflector was developed. The model contains a central mirror, a set of petals, hinges, locks and actuators for opening the mirror. 3D printing technology, CNC (computer numerical control) milling, plastic injection molding and carbon fiber technologies have been tested for central mirror and petals of the model fabrication. The results of computer and physical simulation are presented in the paper.
Determination of the regularities of the covered wagon supporting structure dynamic loading when conducting fire from it in the horizontal plane
Authors: Fomin O , Lovska A , Gerlici J , Fomina Yu , Fedosov-Nikonov D , Prokopenko P 
Published: January 2021

Abstract
A study of the supporting structure dynamic loading of a covered wagon for the military equipment transportation and for firing has been carried out. A mathematical model has been drawn for this purpose, taking into account the vertical and angular displacements relative to the longitudinal axis (side rolling) of the wagon supporting structure when firing. Accelerations as the components of the dynamic load acting on the wagon supporting structure have been determined. It was found that the accelerations acting on the wagon supporting structure in the vertical plane were about 6.0 m/s2 (0.6 g). In the horizontal plane, the accelerations were 2.6 m/s2 (0.26 g). That is, the wagon movement can be assessed as “satisfactory”. To reduce the wagon dynamic loading during the conduct of fire, it is proposed to install elastic vibration dampers under the support sectors. In this case, the horizontal acceleration was about 2 m/s2 (0.2 g). Taking into account the proposed technical solutions, the wagon dynamic load is reduced by about 25% in comparison with the case of the rigid interaction of the sector with the frame. The strength analysis of the covered wagon bearing structure has been carried out. It was found that the maximum equivalent stresses are concentrated in the area of the front stops and are about 315 MPa. The conducted research will contribute to the creation of recommendations for the design of covered wagons for the military equipment transport and for firing, as well as to increase the efficiency of the railway transport operation..
Determination of residual resource of flat wagons load-bearing structures with a 25-year service life
Authors: Fomin O , Vatulia G , Horbunov M , Lovska A , Píštěk V. , Kučera P. 
Published: January 2021

Abstract
The article determines the residual resource of flat wagons load-bearing structures with a 25-year service life. For this purpose, field studies of the technical condition of the load-bearing structures of flat wagons based on the wagon depot of the Foundation of the Southern Railway branch of JSC “Ukrzaliznytsia” were carried out. The flat wagon of model 13-401 was chosen as the subject. It is established that the design service life of the load-bearing structures of the studied flat wagons, taking into account the extension of their operation is not less than 18 years. The strength of the load-bearing structure of the flat wagon in the environment of SolidWorks Simulation (CosmosWorks) software by the finite element method is calculated. It is established that the maximum equivalent stresses occur in the zone of interaction of the spine beam with the pivot be equal to 337.5 MPa. Therefore, the strength of the load-bearing structure of the flat wagons is provided. The estimation of the course of the flat wagons is determined. The research was carried out in the vertical plane during the movement of the butt rail track. The calculation was performed in the MathCad software environment by the Runge-Kutta method. The assessment of the wagon is “excellent”. The conducted researches will promote increase of efficiency of combined transportations in the international communication and strengthening of foreign economic positions of Ukraine in the market of transport services.