bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro effects of Type I interferons (IFNτ and IFNα) on bovine hepatocytes cultured with or without Kupffer cells
Authors: Endriß Kai Josef , Meyerholz Marie Margarete , Fischbach Teresa , Brimmers Lutz , Pfarrer Christiane , Marth Christina Deborah , Schmicke Marion
Published: February 2021

In cattle, maternal recognition of early pregnancy depends on the effects of the embryonic signal interferon (IFN)-τ. IFN-stimulated genes have been upregulated in the maternal liver during early pregnancy. In this study, primary hepatocyte cell culture models were evaluated for their suitability to test Type I IFN effects invitro. The expression of target genes (interferon-stimulated gene 15 (ISG-15), interferon-induced GTP-binding protein (MX-1), C-X-C motif chemokine 10 (CXCL-10), CXCL-5, insulin-like growth factor 1 (IGF-1), IGF binding protein 2 (IGFBP-2)) was measured using reverse transcription–quantitative polymerase chain reaction in hepatocytes from monoculture or in indirect coculture with Kupffer cells (HKCid) on Days 1, 2, 3 and 4 of culture (n=21 donor cows). Gene expression was also measured on Day 4 after challenging the cultures with recombinant IFNτ, IFNα, progesterone (P4), IFNτ+IFNα or IFNτ+P4 for 6h. A significant increase in the mRNA expression of target genes in hepatocytes was shown in response to stimulation with IFNτ. The Kupffer cells in coculture did not influence the effects of IFNτ in hepatocytes. In conclusion, primary bovine hepatocyte cultures are suitable for stimulation experiments with Type I IFNs and as an extrauterine model for embryo–maternal communication. The proposed endocrine action of IFNτ in the liver may affect maternal metabolism and immune function in the liver.
Frame decompositions of bounded linear operators in Hilbert spaces with applications in tomography
Authors: Hubmer Simon , Ramlau Ronny
Published: February 2021

We consider the decomposition of bounded linear operators on Hilbert spaces in terms of functions forming frames. Similar to the singular-value decomposition, the resulting frame decompositions encode information on the structure and ill-posedness of the problem and can be used as the basis for the design and implementation of efficient numerical solution methods. In contrast to the singular-value decomposition, the presented frame decompositions can be derived explicitly for a wide class of operators, in particular for those satisfying a certain stability condition. In order to show the usefulness of this approach, we consider different examples from the field of tomography.
Coarse-grained model of a nanoscale-segregated ionic liquid for simulations of low-temperature structure and dynamics
Authors: Kloth Sebastian , Bernhardt Marvin P , van der Vegt Nico F A , Vogel Michael
Published: February 2021

We perform molecular dynamics simulations to study the structure and dynamics of the ionic liquid [Omim][TFSI] in a broad temperature range. A particular focus is the progressing nanoscale segregation into polar and nonpolar regions upon cooling. As this analysis requires simulations of large systems for long times, we use the iterative Boltzmann inversion method to develop a new coarse-grained (CG) model from a successful all-atom (AA) model. We show that the properties are similar for both levels of description at room temperature, while the CG model shows stronger nanoscale segregation and faster diffusion dynamics than its AA counterpart at low temperatures. Exploiting these features of the CG model, we find that the characteristic length scale of the structural inhomogeneity nearly doubles to ∼3 nm when the temperature is decreased to about 200 K. Moreover, we observe that the nanoscale segregation is characterized by a bicontinuous morphology. In worm-like nonpolar regions, the ends of the octyl rests of the cations preferentially aggregate in the centers, while the other parts of the alkyl chains tend to be aligned parallel on a next-neighbor level and point outward, allowing for an integration of the imidazolium head groups of the cations into polar regions together with the anions, resembling to some degree the molecular arrangement in cylindrical micelles.
Magnet alignment monitoring system with eigenfrequency-based wire sag correction
Authors: Zhang C , Azumi N , Fukami K , Kimura H , Kiuchi J , Matsui S , Takemura Y , Takano S , Watanabe T
Published: February 2021

The precision of magnet alignment in next-generation light sources is critical. To achieve this, the multipole magnets on a common girder of SPring-8-II, an upgrade of SPring-8, are planned to be aligned using the vibrating-wire technique. We developed an alignment monitoring system to monitor the magnet positions in the tunnel where the vibrating-wire technique cannot be executed while the magnets are not energized or when there are vacuum chambers in the magnet center. The alignment monitoring system utilizes a non-contact capacitive sensor embedded in a ceramic ball to measure the wire position relative to the center of the ball and derives the wire sag by measuring a higher mode eigenfrequency. The constitution of this system is illustrated for relevant studies, including the investigation of wire sag against the eigenfrequency, observation of the actual wire sag at a test bench, and validation of the system on the girders for the prototype magnets of SPring-8-II. The system measured the positions of a series of magnets with a precision of ±4 µm (peak to peak) in a 4 m range, in both the horizontal and vertical directions, meeting the requirement of SPring-8-II.
Delay induced dynamical behaviors in a stochastic insect outbreak model in presence of Michaelis-Menten type harvesting
Authors: Mandal Saroj Kumar , Poria Swarup
Published: February 2021

In this paper, we have considered stochastic insect outbreak model in presence of Michaelis-Menten type of harvesting. The growth of the insect species is taken as delayed logistic type together with a multiplicative noise term. The impact of internal environmental disturbances on the insect population is taken into account by adding an additive noise term in the model. The effects of the noises, cross correlation strength of the noises and time delay on the insect population are investigated and observed very rich dynamical behaviors. It is ascertained that multiplicative noise reduces population size greatly than additive noise. As usual, increase of harvesting of insect species reduces the population size at faster rate. Regime shift is possible depending on multiplicative noise only in contrast it is not possible via only additive noise. One of the key finding is the noise-delayed switching phenomenon for negatively correlated noises.
Study on the influence factors of aging property of nano-modified asphalt
Authors: Sun Huadong , Yao Ming , Jiang Peng , Ding Yongling , Zhang Aiqin , Wang Baoqun , Liu Hongke
Published: February 2021

In order to study the aging property of nano-modified asphalt, the values of nano-modified asphalt like softening point, penetration, ductility and viscosity etc. before and after the aging test were measured by controlling the content and types of nanomaterial, and then the relevant aging property indexes were calculated, the aging property optimum of the modified asphalt was determined by scientific methods of mathematical statistics and analysis. The testing results show that nanomaterial can effectively improve the high-temperature stability, low-temperature crack resistance and viscoelasticity of nano-modified asphalt. The content and type of nanomaterial have a great influence on the aging property of modified asphalt, the anti-aging performance of nano-modified asphalt with 0.5% titanium dioxide content is better.
Automatic profile tracking of deformed surface in mirror milling based on ultrasonic measurement
Authors: Guo P , Wu Z M , Zhang Y , Zhu L M
Published: February 2021

Mirror milling is an effective and environmentally friendly means to manufacture large thin-walled parts. The remaining wall thickness of such parts is supposed to be strictly controlled to balance strength and weight reduction. However, the clamping deformation will lead to overcut or undercut if the nominal tool path is directly utilized. To address this issue, it would be helpful to scan and reconstruct the deformed unknown workpiece surface and then adjust the nominal tool path. In this paper, an automatic profile tracking approach is proposed to adaptively sample the deformed surface and reconstruct the surface model, based on a multi-ultrasonic-probe measurement system. The adaptive sampling algorithm calculates the position and surface normal of the next sampling point simultaneously based on a curvature sphere, which utilizes the surface information of the local area covered by the multi-ultrasonic-probe system. Moreover, a boundary processing algorithm is proposed to ensure the sampling process is carried out inside the boundary. The feasibility of the proposed automatic measurement method was validated through experiment.
Decision-making and computational linguistic tools application for overall estimation of the level of social tension
Authors: Shchoholiev Maksym , Andriichuk Oleh , Tsyganok Vitaly , Tretynyk Violeta
Published: February 2021

The study of social tension, its causes and laws of variation, as well as establishing its level is crucial during crises, epidemics and wars. The purpose of this research is to develop the system for determining the level of tension in society on the basis of data from social networks using decision-making and computational linguistic tools. The impact of various factors on the growth of social tensions is determined with the help of knowledge bases built by means of decision support systems. To analyse the emotionality of comment on news publications the TF-IDF and Word2vec methods are used. Within the framework of the method of goal dynamic estimating of alternatives, the level of social tension is determined as the degree of achievement of the main goal, the ratings of news publications and the ratings of news events that contributed to the increase in social tension are calculated. The study presents the efficient method of determining the level of social tension and defining the main factors that have the greatest impact on the growth of social tension. Further studies are needed to improve the estimates of factors and the overall estimate of social tension.
The vibration character and reducing vibration analysis about series manipulator’base
Authors: Xin Wu Zai , Tai Li
Published: February 2021

During the running of serial manipulator, unbalanced force produced by base with respect to the floor has a great effect on the accuracy of manipulator’s end. Aiming at the above problem, we take the three-degree-of-freedom serial manipulator as an example to analysis. First, taking advantage of the methodology of Newton-Euler dynamics to derive the relative force between two joint rods and base with respect to the floor while the manipulator is at the period of working. Then, building the spring-damp vibration model to calculate the parameter formula of the base with relative to the ground. Finally, analysing the characteristics of vibration and giving measures of reducing vibration, simulating to prove the effectivity using MATLAB. The simulation results show that when choosing other values of ωn and ξ, vibration amplitude has significant decrease compared with the conditions of ωn = ωi or ξ =0.414 when other parameters unchanged, which provides a certain reference for further research on vibration reduction of series manipulator.
Simulation study on pedestrian evacuation optimization in a multi-exit building
Authors: Fu Yanyun , Shi Wenxi , Zeng Yiping , Zhang Hui , Liu Xiaodong , Liu Yi
Published: February 2021

Two multi-exit selection models based on social force model are presented to simulate pedestrian evacuation, and the model coefficients are optimized by considering the effect of the exit distance, exit width, crowd number and distribution. The evacuation processes employing shortest distance evacuation strategy, static and dynamic exit selection model are compared. The effects of the crowd number, distribution and desired speed are investigated on the evacuation time and balance degree with the static and dynamic exit selection model. The effects of group size and group shape on the evacuation time in dynamic exit selection model is explored. The simulation results indicate that the proposed dynamic exit selection model can realistically reflect the pedestrian evacuation and help predicate the time available in building spaces with multiple exits, which can lead to a shorter evacuation time and higher evacuation efficiency. The study has some guiding significance for emergency evacuation and exits design of multi-exit buildings.
Modeling and adaptive torque computed control of industrial robot based on lie algebra
Authors: Mei Zaiwu , Chen Liping , Ding Jianwan
Published: February 2021

Computed Torque Control (CTC) is the most direct and effective way to improve the motion control performance of robot. But the computation of the joint torque is quite difficult, and because of the uncertainty of the parameters, an accurate inverse robot dynamic model for torque generation is difficult to obtain. An efficient inverse dynamic model of the industrial robot based on lie algebra is proposed and applied to the computed torque control. In order to overcome the uncertainty of parameters, the inverse robot dynamic model is linearized and an adaptive computed torque control is proposed. In order to validate the adaptive torque computed control method, a multi-domain integrated system model of 6-DOF industrial robot is established and the simulation results show that the adaptive computed torque control system has the function of parameter self-learning, the inaccurate parameters converge to the true value finally. The adaptive control shows better control performance than the traditional computed torque control.
Application of OFDM transmission method for railway signalling system via track circuit
Authors: Higuchi Ryo , Mochizuki Hiroshi , Nakamura Hideo , Ishikawa Ryo , Sano Minoru , Nishida Satoshi
Published: February 2021

At present, railway signalling systems in which control information is transmitted via track circuits (rails) have been deployed in many applications, such as automatic train control (ATC) systems in Japan. In these systems, it is difficult to increase the transmission speed due to the transmission characteristics of rails. To overcome this problem, we have proposed a new transmission method using orthogonal frequency division multiplexing (OFDM) and evaluated a configuration in which data judgment using majority decision was applied for improving the bit error rate (BER) characteristics. In this paper, we describe an FPGA implementation of our proposed method and the performance of the implemented devices.
Vger: a VRF based cross-chain mechanism for blockchains
Authors: Shu Fangxing , Lei Kai
Published: February 2021

As a new distributed computing paradigm, blockchain is rapidly evolving in areas such as digital finance and cryptocurrency. However, existing blockchain projects adopt different blockchain architectures and protocols, as a result it is difficult for different blockchain systems to flow value to each other or communicate information, and different blockchain systems become isolated islands. This has brought limitations to the usable range, function and scalability of blockchain technology. In order to solve this problem, and bulid trust between different blockchain networks, cross-chain technology has been proposed and received a lot of attention. In this paper we proposed a cross-chain mechanism based on verifiable random functions ( VRF ) and threshold cryptography, we name this scheme as Vger. In Vger, through VRF based cryptographic sortition to select management committee for escrow account and dynamic security setting mechanism, that optimize the security and efficiency about cross-chain transaction.
Exploring the possibility space: taking stock of the diverse capabilities and gaps in integrated assessment models
Authors: Keppo I , Butnar I , Bauer N , Caspani M , Edelenbosch O , Emmerling J , Fragkos P , Guivarch C , Harmsen M , Lefèvre J , Le Gallic T , Leimbach M , McDowall W , Mercure J-F , Schaeffer R , Trutnevyte E , Wagner F
Published: February 2021

Integrated assessment models (IAMs) have emerged as key tools for building and assessing long term climate mitigation scenarios. Due to their central role in the recent IPCC assessments, and international climate policy analyses more generally, and the high uncertainties related to future projections, IAMs have been critically assessed by scholars from different fields receiving various critiques ranging from adequacy of their methods to how their results are used and communicated. Although IAMs are conceptually diverse and evolved in very different directions, they tend to be criticised under the umbrella of ‘IAMs’. Here we first briefly summarise the IAM landscape and how models differ from each other. We then proceed to discuss six prominent critiques emerging from the recent literature, reflect and respond to them in the light of IAM diversity and ongoing work and suggest ways forward. The six critiques relate to (a) representation of heterogeneous actors in the models, (b) modelling of technology diffusion and dynamics, (c) representation of capital markets, (d) energy-economy feedbacks, (e) policy scenarios, and (f) interpretation and use of model results.
Research on Customized Passenger Route Optimization Based on Improved Genetic Algorithms
Authors: jun Ma , Hongzhou Wu , Xiu Zhang , Huijuan Zheng , Yufei Chen
Published: February 2021

In view of the passenger travel demand changing from popularization to high quality and customization, a customized passenger route planning method with multi-departure point and multi-arrival point is proposed, and a customized passenger route optimization model with the minimum total cost for enterprise operation and passenger travel time is established. An improved genetic algorithm is proposed to solve the optimization model. Finally, the feasibility of the optimization method and the effectiveness of the improved genetic algorithm are verified by a practical case.
Land subsidence in Beijing from 2017-2018 revealed by Sentinel-1A TOPS time series interferometry
Authors: Ran Peilian , Li Shaoda , Dai Keren , Yang Xiaoxia
Published: February 2021

Beijing is one of the largest cities in China, which has suffered from land subsidence for a long time. According to the study from 2005 to 2017, the maximum subsidence rate of Beijing is more than 10 cm/year. This paper will use Sentinel-1A TOPS data for the first time to reveal the land subsidence of Beijing from 2017 to 2018 by using time series interferometry. SBAS-InSAR technology was used for time series analysis. The annual mean subsidence rate and time series subsidence of Beijing were obtained. The results show that the east of Chaoyang district and the northwest of Tongzhou district were the severe subsidence areas in Beijing, and the subsidence rate is more than 10 cm/year, which indicates that the subsidence area in Beijing is continuous in recent years, and corresponding measures should be taken by the government.
Design and Kinematic Analysis of a Wall-climbing Robot for Bridge appearance Inspection
Authors: Qin Yue , Dong Shaojiang , Pang Rong , Xia Zongyou , Zhou Qingsong , Yang Jianxi
Published: February 2021

In order to solve the maneuverability and safety of large bridge appearance inspection, a new type of hexapod wall-climbing robot is designed. As an important branch of mobile robot field, the organic combination of ground mobile robot technology and adsorption technology greatly expands the application range of robot. This paper introduces the mechanical structure of two self-designed legged wall-climbing robots, puts forward four problems on the quadruped robot and improves them on the hexapod robot. At the same time, in order to control the hexapod wall-climbing robot, the kinematics model of the hexapod wall-climbing robot must be established, and on this basis, the forward and inverse kinematics equations of the robot should be solved. The research results show that the two new robots meet the requirements of reliable adsorption and flexible movement, and have large application scenarios. The forward and inverse kinematics solved by the established kinematics model is proved to be effective by experiments.
Research on Optimization of Hoisting Sequence of Main Girder of Asymmetric Long-span Suspension Bridge
Authors: Xiong Shaohui , Li Yang , Fu Bin
Published: February 2021

With the emergence of asymmetric long-span suspension bridge, it is necessary to study the optimization of hoisting sequence of the main girder of this type of suspension bridge. According to the relationship between the lifting sequence of the main girder and the pushing scheme of the pylon, the method flow of optimizing the lifting sequence of the main girder of the asymmetric long-span suspension bridge is given. Taking an asymmetrical long-span suspension bridge in Guangdong Province as an example, this method is used to optimize the hoisting sequence of the main girder and put it into practice. Good results are obtained and verified: the hoisting of the main girder should be carried out from the middle of the span to the two pylons, and the hoisting speed of the middle side span should be consistent with the proportion of the standard beam sections of the middle side span, and the maximum allowable deviation of the pylon and the main girder should be used in the jacking scheme of the pylon The hoisting sequence shall be formulated based on. It can provide a useful reference for the hoisting of the main girder of the same type suspension bridge and the suspension bridge with slings on both sides of the bridge.
State-of-the-art review on asphalt mixture distribution uniformity based on digital image processing technology
Authors: Xiaoli Chen , Jianfei Zhang , Xin Wang , Yongqiang Zhu , Hui Guo , Yidong Xu
Published: February 2021

Asphalt mixture uniformity has an important impact on the long-term performance of pavement. This paper introduces the asphalt mixture uniformity evaluation method based on digital image processing technology, lists a variety of evaluation indicators based on different evaluation ideas, and finally points out the advantages of this method compared with the traditional method and new detection technology, as well as the shortcomings of the current method.
Open block structure planning of eco city based on big data spatial syntax
Authors: Tang Yanming
Published: February 2021

For high-frequency sub-images, a hybrid particle swarm optimization algorithm is used to select the threshold, and the neighbourhood algorithm based on average gradient selection is used for fusion. This algorithm can effectively improve the fusion effect of fused images. The experimental research results show that combining the characteristics of gradient intensity and phase consistency, the characteristic method of compressing the information while retaining important information, which is convenient for real-time processing, is used for related research on sensor image fusion. The application of big data to stock planning will help to promote the reform of planning technology and planning subject, and help historical districts better carry out protection planning, construction implementation and operation management. In order to give full play to the urban spatial function, this paper puts forward an ecological city open block structure planning method based on big data spatial syntax. Taking the big data spatial syntax as the core and taking the practical problems as the guidance, this paper constructs the method system and technical realization of the planning, construction and operation management of the historical block supported by the big data spatial syntax, so as to open the block stock of the ecological city The planning methodology is discussed and innovated.
Stability Analysis of Rock-soil Mixture Slope
Authors: Zhongfeng Yang , Yuqin Ding , Jiangong Chen
Published: February 2021

This research provides a method of random generation of Soil-rock Mixture (SRM) model depends on digital imaging technology and rock stone database technology. With processed rock shape diagrams, database of rock shape had been built and a method of random generation depend on this database had been provided. The SRM backfilled slope models were generated with random generation method. Couples of SRM slope models had been simulated with ABAQUS CAE to study the stability of SRM slope with different parameters variations. The influence of block stones on the slope stability is main caused by rock stones’ slipresistance effect. When the stone content is 40%-50%, the block stones gradually contact with each other and form a framework. The safety factor gradually increases. The spatial distribution of rock stones at the foot of the slope has the most obvious influence on the stability of SRM slope. With the increase of maximum block size, the slope stability decreases firstly and then increase. The sliding resistance effect is the key factor of the SRM slope stability. Aggregation of small size stones or large size stones can change the shape of the sliding surface and have great influence on the stability of the slope.
Road performance and construction of weathered siltstone for expressway subgrade
Authors: De-yong Wang , Jun-long Hu , Jing Wang , Shang-hui Gao
Published: February 2021

Whether weathered siltstone can be used for expressway subgrade filling, there is currently no clear regulation, and there is a lack of relevant evaluation standards. In order to solve the problem of expressway slag disposal and the source of subgrade fillers, relying on an expressway in northern Guangdong, the characteristics of compaction and disintegration of weathered siltstone material are tested and studied. The research shows that: the weathered sandstone material has strong softening and disintegration characteristics, but good compaction performance, and can be used for expressway subgrade filling. The filling process parameters of weathered siltstone subgrade are determined through field test.
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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
The closing lemma and the planar general density theorem for Sobolev maps
Authors: Azevedo Assis , Azevedo Davide , Bessa Mário , Torres Maria
Published: February 2021

We prove that given a non-wandering point of a Sobolev-

(
1
,
p
)

(1,p)

homeomorphism we can create closed trajectories by making arbitrarily small perturbations. As an application, in the planar case, we obtain that generically the closed trajectories are dense in the non-wandering set.