bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical simulation and mechanical analysis of square corrugated steel pipe gallery with different top angel
Authors: Zheng Jiayan , Yang Xiaomeng , Liu Haijing , Xu Chao , He Shiyong 
Published: February 2021

Abstract
To investigate the load and stress characteristics of the underground square arch gallery, a numerical model was proposed. Equivalent stress, lateral displacement and vertical displacement of the structure of different angles were discussed, with the increase of filling height, and the appropriate section angle was selected according to the variation rules of the stress. The results show that the maximum Mises equivalent stress is lower when the top Angle is 50° than that of the other two top angles. The maximum transverse displacement is the smallest when the pipe top Angle is 50°, and the structure has a better ability to resist the transverse displacement.
Surface modification of tool steel by using EDM green powder metallurgy electrodes
Authors: Balanou M , Karmiris-Obratański P , Papazoglou E L , Galanis N I , Markopoulos A P 
Published: February 2021

Abstract
Electro-discharge machining (EDM) is mostly used for machining difficult-to-cut materials which are difficult to machine by conventional machining processes. In recent years, EDM is also used for surface modification. This work aims to investigate the phenomenon of surface modification of tool steel Calmax (Uddeholm) by EDM process using Cu-ZrO2 powder metallurgy green compact electrode. Results show that the higher Material Transfer Rate of 46.5 mgr/min is achieved on the combination of Ip=9A and Ton=25 μs. The effect of peak current and pulse duration on the material transfer rate and surface roughness (Ra and Rz) was investigated. Machined surfaces were characterized by scanning electron microscopy (SEM).
Direct 3D Printing of a hand splint using Reverse Engineering
Authors: Kechagias J , Kitsakis K , Zacharias A , Theocharis K , Aslani K-E , Petousis M , Fountas N A , Vaxevadnidis N M 
Published: February 2021

Abstract
The present work is focused on the direct manufacturing of a hand splint using free-open access software and a low-cost three-dimensional printer (3DP). The hand digital model was created using panoramic photos by a common mobile phone camera. The photos were used as input to the “3DF-Zephyr” free software for creating the hand surface model. Then, the hand surface model was transferred into the “Autodesk fusion 360” free software and the surface model of the hand splint was generated and modified according to the design requirements. Sequentially, both hand and hand splint were translated to Stereolithography (STL) files and transferred to open access “MakerBot” 3D printing software in order to prepare the G-codes for 3D printing. A low cost 3D printer was used for building the models while Polylactic acid (PLA) was the material of the customized 3D physical models.
A new and lean finite element model to predict the out of plane crash behaviour of aluminium honeycomb structures
Authors: Chacko Kevin , Asadi Mehrdad , Ramezanpour Ahad , Markopoulos Angelos P. 
Published: February 2021

Abstract
Aluminium honeycombs are well-known anisotropic structures which are commonly used as energy absorber units. In the past decades, several researchers have focused on developing finite element models credible enough to predict the crash behaviour of honeycomb structures. A number of modelling methodologies have been developed and validated to closely represent the structural behaviour under various boundary conditions. Due to the limitations with modelling the structure accurately as well as the adhesive failure and trapped air, presents a serious challenge to predict the crushing behaviour of honeycomb structures. This paper introduces multiple simplified FE models and the results from simulations are compared with experimental data to evaluate the most effective model. The results have also been compared with our existing article which used LSDYNA for numerical analysis. The techniques proposed in this paper show good correlation with the mentioned experimental data and the LSDYNA model. Thus, the simplified FE models are regarded as validated and credible enough to predict out-of-plane crash behaviour of aluminium honeycomb. Altair’s HyperMesh and HyperCrash were used to create the FE models and the dynamic explicit code RADIOSS to solve the models.
Computer modelling-based selection of accelerated cooling parameters for advanced high-strength structural steel
Authors: Efremenko V G , Zotov D S , Zurnadzhy V I , Kussa R A , Savenko V I , Sagirov R I , Bocharova O A , Efremenko A V 
Published: February 2021

Abstract
The article describes the working principles and configuration of the computer system applied for selecting parameters of accelerating water cooling of rolled sheets made of low-carbon advanced strength steel. The system is based on mathematical models using empirical regression equations that describe the interconnections between working parameters of cooling equipment and the technological parameters of thermal processing. The equations are outlined and discussed. The results of computer modelling verification in industrial trials are presented. The case-study involved computer system concerning steel properties and microstructure is described.
Structures for Metamaterial Superlenses Used in Medical Imaging
Authors: Ionescu Daniela , Apreotesei Gabriela 
Published: February 2021

Abstract
The metamaterial superlenses for imaging proteins, viruses, and DNA have to present a high resolution, which cannot be ensured by classical lenses. Such a material for lenses exceeds the Abbe-Rayleigh diffraction limit, leading to a nanoscale level of resolution, a several times better than the classical diffraction limits. We have illustrated here a hotspot size of ca. 0.25 – 0.28 λ, corresponding to a numerical aperture of about 1.4. The used metamaterial structures are isotropic negative index metamaterials (NIMs), with negligible losses. Material combinations of metallic nanoparticles (with dimensions of tens of nm) inserted in a dielectric slab have been considered for study. Microcomponents periodicity in the layer is of a few hundred of naometers. Material properties evolve in function of the constituent’s nature and dimensions. Refraction index in function of wavelength was determined and represented on graphs in order to illustrate the domain of negative values and the manner in which it can be controlled at structure level. Analysis was performed in visible and IR range by simulation methods, using the HFSS program and a proper algorithm based on physical considerations.
Optimization of dynamic absorber parameters for protecting the machines against the vibrations transmitted through their base
Authors: Ibănescu R , Ibănescu M 
Published: February 2021

Abstract
The correct functioning of machines could be affected by the vibrations transmitted through their base from other devices. The first possible protection measure is to support these machines on elastic elements with damping. The present work presents a protection solution which consists in the attachment of a dynamic absorber with viscous friction to the considered machine, in order to diminish the amplitudes of the vibrations caused by base movement. The mathematical model is developed for the real case when the base vibrations are not transmitted to the machine, but to the elastic supporting elements. The analytical expression of machine vibration amplitude in steady state is obtained. This amplitude could be diminished by an accurate choice of the three dynamic absorber parameters (mass, elastic constant, coefficient of viscous friction). An optimization program conceived in MATLAB provides the values of these parameters which lead to the minimum amplitude of machine vibrations.
Optimization of the production plan of drill bits with fuzzy constraints based on a heuristic method
Authors: Orazbayev B B , Ospanov Ye A , Orazbayeva K N , Kulmagambetova Zh K , Seidaliyev A A , Smailova U M 
Published: February 2021

Abstract
The problem of optimizing the production plan under fuzzy constraints is formulated using the theory of fuzzy sets. To solve the obtained fuzzy optimization problem, a heuristic method is proposed, in which, on the basis of the use of expert information and the knowledge of experts, the decision-maker in the optimization process and the choice of the best solution, it makes possible to improve the solution of the fuzzy problem. The results obtained are implemented and applied when solving the problem of optimizing the production plan of a plant for the production of diamond drill bits under fuzzy constraints. It is shown that when solving the optimization problem based on the proposed fuzzy approach, the plant’s profit from the sale of different types of bits increases to 8%.
Forming a convex flange by pulsed-magnetic field pressure
Authors: Kurlaev N V , Matveev K A , Ahmed Soliman M E , Detinov M B 
Published: February 2021

Abstract
A large number of parts used in aircraft are D16AM sheet metal flanged parts. Stress plays a role in reducing damage and improving plasticity. Common to such parts is the necessary shaping to increase rigidity and reduce weight. High strain rate forming is a dynamic shaping process that uses the instantaneous impact pressure generated by suddenly released energy to plastically process metal sheets for the numerical study and simulation of the process of magnetic-pulse forming (MPF) of convex flanging. The LS-DYNA program was used, a universal software multi-purpose system of the finite element complex. A computer simulation technique was developed, which allows, in accordance with the required geometry of the die surface and with the selected loading schemes, to take into account the change in load over the deformable area and set the distribution of the pulsed magnetic field (PMF) pressure intensity, vary the geometric parameters of the blanks and the characteristics of the material. In the case of elastic-plastic deformation of a solid, within the framework of the modern approach, it is a cooperative deformation process caused by correlated motion in an ensemble of crystal lattice dislocations. This causes a change in the volume of a deformable body under load by the pressure of a pulsed magnetic field; when the load is removed, the internal stress is almost completely removed and the volume of the body takes the required shape in our case in the form of a convex flange.
Simulation of electromagnetic and thermal processes during induction heating of pipelines in Elcut 5.1
Authors: Bocharova O A , Murygin A V , Tynchenko V S , Kurashkin S O , Bocharov A N , Petrenko V E 
Published: February 2021

Abstract
The article discusses the issues of modeling induction heating in the process of induction brazing of pipelines in a protective gas environment. Elcut 5.1 software product is used for modeling. The modeling of the following physical characteristics of the induction heating process is carried out: the electromagnetic field formed by the inductor, the distribution of eddy currents over the elements of the pipe being welded, the temperature distribution. On the basis of the developed simulation models, the influence of the position of the pipeline system assembly in the inductor window and the influence of the frequency of the current generated by the generator on the efficiency of the induction heating process are evaluated. The results obtained in the course of the study make it possible to efficiently adjust the technological parameters of the process of induction brazing of pipelines in protective environments and, accordingly, to improve the quality of the formed permanent joints.
Rigid chain in parallel kinematic positioning system
Authors: Kubrikov M , Pikalov I , Saramud M 
Published: February 2021

Abstract
The article presents an analysis of the trends in the development of kinematic structures of modern machine-building technological equipment. The prospects of using machines with parallel kinematics in processing, measuring and handling equipment, their advantages and disadvantages are demonstrated. It is shown that it is inexpedient to use ball screw drives in machines with parallel kinematics, performing tasks of low accuracy, but with displacements of more than 3000 mm. The rigid chain system of the Serapid firm and the possibility of its use in machines with parallel kinematics are considered. A schematic solution of a three-coordinate manipulation robot based on parallel kinematics with drive mechanisms on rigid chains is proposed.
Imperfection of the convergent cross-mapping method
Authors: Bartsev S , Saltykov M , Belolipetsky P , Pianykh A 
Published: February 2021

Abstract
In 2012, the Convergent Cross Mapping method for finding a causal relationship between system variables from their time series was published. This method is widely used in the study of systems of various nature - from assessing the effect of cosmic radiation on the climate, to the study of cerebral activity. The relevance and prospects of using this method prompted us to master it and to apply it to identifying causal relationships between the variables of the “biosphere-climate” system. The obtained results seemed suspicious and forced us to check carefully the adequacy of the CCM conclusions in relation to various model systems. This paper presents examples of model situations when the method gives false estimates of the presence of causal relationships and offers a possible explanation for the causes of false estimates appearance.
Coagulation of submicron particles in gas-dispersed media due to high-intensity shock-wave exposure
Authors: Khmelev V N , Shalunov A V , Nesterov V A , Tertishnikov P P , Golykh R N 
Published: February 2021

Abstract
The article presents an approach to solving the problem of gas cleaning from high-dispersed aerosols with particles less than 2.5 microns. The proposed approach is based on the use of high–intensity shock-wave ultrasonic exposure, which provides an increase in the coagulation efficiency of high-dispersed particles up to 20 times (in comparison with harmonic ultrasonic exposure). The article considers an example of the implementation of the process of shock-wave exposure on aerosols using previously developed ultrasonic emitters. The results obtained are the basis for the make and use of a new class of gas cleaning equipment for capturing submicron particles in solving the problem of environmental and human protection.
Influence of graphene stacks on the structure and conductivity of shungite carbon
Authors: Antonets I V , Golubev Ye A , Shcheglov V I 
Published: February 2021

Abstract
The influence of graphene stacks on the formation of structural and electrical parameters of shungite carbon was determined. The spatial distribution map of graphene layers and stacks consisting of these layers was obtained by the STEM method. Statistical analysis of images of graphene stacks and the gaps between them was performed. Based on the data obtained, a simplified regular structure model is proposed, within the framework that allows one to quantitatively estimate the spatial dimensions of the carbon regions and describe the integral conductivity of shungite carbon.
The moment of inertia of V-shaped internal combustion engines
Authors: Egorov A V , Egorova O G , Smikulis Yu E , Ignatiev A V , Stepanova K S , Lysyannikov A V , Kaizer Yu F , Matkerimov T I 
Published: February 2021

Abstract
This work contains a solution to the problem of developing a mathematical model and the results of numerical simulation of the change in the inertia of the moving mass V-shaped piston internal combustion engines (ICE) reduced to the axis of rotation of the crankshaft depending on the angle of rotation of the crankshaft during one revolution. The solution of this problem is an important step in the mathematical description of the dependence of the torque developed by the V-shaped piston ICE, depending on the angle of rotation of the crankshaft. Knowing the dependence of the torque developed by the V-shaped piston ICE, depending on the angle of rotation of the crankshaft, is a prerequisite for designing and optimizing the design of non-linearly loaded processing equipment using V-shaped piston ICEs as the drive. The results of mathematical modeling show that the moment of inertia of the moving masses of the V-shaped piston ICE reduced to the axis of rotation of the crankshaft is constantly changing during one revolution of the crankshaft. The greatest change in the moment of inertia of the moving masses reduced to the axis of rotation of the crankshaft takes place in 2- and 4-cylinder V-shaped piston internal combustion engines.
Effect of vibration treatment during welding on technological strength of chromium martensitic steel P91
Authors: Fairushin A M , Kinev S A , Zaripov M Z 
Published: February 2021

Abstract
The paper shows the possibility of using the technology of vibration treatment in the process of welding of high-temperature chromium steel of martensitic class P91 applied to the product to increase the technological strength of welded joints and the effect of this technology on mechanical properties before and after thermal treatment. Application of vibration action on welding bath and weld seam in process of manufacturing of welded structure may allow to reduce inhomogeneity of weld metal structure in liquid phase, as well as increase its microchemical inhomogeneity within crystallites during crystallization, reduce grain size due to more efficient heat removal and increase of number of crystallization centers. On the example of manufacturing the turbine support housing of the gas turbine drive, it is shown that it is necessary to replace part of the heat treatment operations with other more energy - efficient and less labor-intensive operations. Results of studies of influence of vibration treatment of welded joint on tendency of welded joint metal to form cold cracks, strength, hardness and impact toughness are given. Based on the obtained results, diagrams of average values of parameters are constructed and conclusions are drawn on the possibility of using the technology of vibration treatment of the turbine casing in the process of welding in order to reduce the number of heat treatment operations during its manufacture.
Control by the accuracy of the results of studies for the cadmium content in samples applying the microwave laboratory system PLP-01M
Authors: Tretyak L N , Rebezov M B , Korablev A V , Mikhaylova T M , Voskanyan E A 
Published: February 2021

Abstract
The article states that in order to compare the results obtained while operating on the atomic absorption spectrometer “Kvant-2AT” applying the microwave laboratory system PLP-01M and during the sample preparation in accordance with GOST 26929 “Raw materials and food products. Sample preparation. Mineralization to determine the content of toxic elements”, on operating samples, the products were selected that most fully cover the range of results obtained during the research. Some research results and data analysis were carried out within 30 operating days. The data were obtained while working on the Kvant-2AT atomic absorption spectrometer, taking into account the application of the PLP-01M microwave laboratory system and while the sample preparation in accordance with GOST 26929. The average values obtained under repeatability conditions were put in the table. The analyte cadmium was supplemented to assess the accuracy of the obtained values. The implementation of sample preparation methods taking into account the microwave decomposition of the sample in the case of using the microwave laboratory system PLP-01M and while sample preparation in accordance with GOST 26929-94 achieves the precision of the analysis results both under conditions of repeatability and under conditions of intermediate precision.
Control by the accuracy of the results of studies for the lead content in samples applying the microwave laboratory system PLP-01M
Authors: Rebezov M B , Assirzhanova Zh B , Dautova Assel , Derkho M A , Meshcheryakova G V , Gumenyuk O A 
Published: February 2021

Abstract
The article presents the analysis of the study results of samples for lead content by their determination on the atomic absorption spectrometer “Kvant-2AT”, taking into account the use of the microwave laboratory system PLP-01M and while the sample preparation in accordance with GOST 26929 “Raw materials and food product. Sample preparation. Mineralization to determine the content of toxic elements”. A fundamentally new method of the sample preparation is used in the microwave laboratory system PLP-01M. The decomposition was carried out in a closed system, i.e. sealed fluoroplastic vessels under the influence of high temperature, pressure and microwave field. The microwave field was created by a special generator-magnetron in the operating chamber of the furnace. According to the assessment results of the operational control of the measurement procedure applying samples for the lead control when the microwave laboratory system PLP-01M was introduced in the laboratory; the analysis procedure was found satisfactory.
Individual changes in anthropometric measures after age 60 years: a 15-year longitudinal population-based study
Authors: Guo Jie , Shang Ying , Fratiglioni Laura , Johnell Kristina , Welmer Anna-Karin , Marseglia Anna , Xu Weili 
Published: February 2021

Abstract

Background
weight loss is commonly observed with ageing. We explored the trajectory of body mass index (BMI) and two proxies of muscle mass—calf circumference (CC) and mid-arm circumference (MAC)—and identified their determinants.

Methods
within the SNAC-K cohort, 2,155 dementia-free participants aged ≥60 years were followed over 15 years. BMI, CC and MAC were measured at baseline and follow-ups. Baseline sociodemographic and lifestyle factors were collected through interviews. Diabetes and vascular disorders were diagnosed by physicians through clinical examination and medical records. Data were analysed using linear mixed-effect models stratified by age (younger-old [&lt;78 years] vs. older-old [≥78 years]).

Results
over the 15-year follow-up, BMI remained stable among participants aged 60 years at baseline (βslope = 0.009 [95% confidence interval −0.006 to 0.024], P = 0.234) and declined significantly among those aged ≥66 years, while CC and MAC declined significantly across all age groups. The decline over 15 years in BMI, CC and MAC separately was 0.435 kg/m2, 1.110 cm and 1.455 cm in the younger-old and was 3.480 kg/m2, 3.405 cm and 3.390 cm in the older-old. In younger-old adults, higher education was associated with slower declines in all three measures, while vascular disorders and diabetes were associated with faster declines. In older-old adults, vigorous physical activity slowed declines in BMI and CC, while vascular disorders accelerated declines in BMI and MAC.

Conclusions
CC and MAC declined earlier and more steeply than BMI. Cardiometabolic disorders accelerated such declines, while higher education and physical activity could counteract those declines.