bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of chemical composition nitrogen-argon-aluminum plasma
Authors: Strunin V I , Khudaibergenov Zh G 
Published: May 2021

Abstract
Plasma-chemical model of magnetron discharge is described. The model allows you to predict the densities of the main plasma components. As a result of numerical modeling, it was found that dissociation of N2
ranges from 10% to 30% with an increase in plasma power, the degree of dissociation increases. The addition of N2
to the plasma leads to a decrease in ion density due to energy consumption for non-ionizing molecular collisions. It can be assumed that aluminum nitride is deposited on the surface of a substrate with a high flow of metal ions in combination with a stream of neutral molecules N2 with a low adhesion coefficient and a relatively small flow of nitrogen ions.
Application of the Herts equation for calculating the parameters of the elastic-plastic central impact of two solid deformable bodies
Authors: Chernyavsky D I , Chernyavsky D D 
Published: May 2021

Abstract
The study of the dynamics of mechanical impact of solid deformable bodies is an urgent problem in mechanics. This problem is associated with the strength calculations of machine parts and mechanisms. The most difficult case is the strength calculation under shock and vibration loads. Exact mathematical equations are obtained only for simple structural elements of machines: balls, rods, plates, beams, etc. The mathematical description of the dynamics of elements of machines of complex shapes under impact conditions is seriously difficult. A method of dynamic strength analysis of machine parts using the Hertzian contact theory is proposed. For the cases under consideration, the impact velocity of two bodies does not exceed 100 m / s.
To the development of the theory of contact interaction in two-roll modules
Authors: Khurramov Sh R 
Published: May 2021

Abstract
The results of the study of the stress-strain state in a two-roll module are presented. The angles that determine the characteristic points of the physical model of the roll contact curves are defined for the case when the strain properties of the material layer and elastic roll coatings are given by power dependences. Formulas are derived for calculating the angles of entering and exit, the angles separating the no-slip zones from the lag and advance slip zones, neutral angles and angles of maximum normal stresses of the two-roll module. It was stated that an increase in the friction coefficient of the roll with the material being processed leads to a decrease in the percentage of slip zones in the contact curve in the driven roll. It was revealed that with an increase in the dynamic coefficient, the slip lag zone decreases, and the advance slip zone increases. It was determined that the faster the feeding rate of the material layer, the greater the percentage of the no-slip zone in the roll contact curve. It was revealed that in the driven roll the neutral angle is inclined towards the entrance of the material layer into the contact zone of the rolls.
A quaternionic description of kinematics and dynamics universal joint
Authors: Mityushov E A , Misyura N E 
Published: May 2021

Abstract
The purpose of the work is figuring out the kinematic and dynamic equations of u-joint motion in the quaternion parametrization. The quaternion description of u-joint kinematics allowed us to formulate the claims about the crosspiece angular velocity projections. We’ve also determined the principle point projection acting on the crosspiece by solving the inverse problem from Euler’s dynamic equations with the found driving shaft’s angular velocity and the inertial crosspiece characteristics.
The modeling results are verified in the computer software-Mathcad and can be used for creating optimal u-joint designs by changing its geometry.
Kinematics of elements of a spherical ball bearing suspension
Authors: Raspopov V Ya , Telukhin S V 
Published: May 2021

Abstract
The kinematic constraint equations of elements of a spherical ball bearing suspension, separator and balls are considered. Based on the equation of motion of the separator and the balls, the angular coordinates of the separator and the trajectory of the centers of mass of the balls relative to the bearing surfaces are determined. Analytical expressions for determining the parameters of the separator and the balls motion are obtained for different ratios between the velocities of rotation of the rotor mounted on the outer ring and the inner ring of the suspension.
Construction project cost estimation model cost dependent on multi-objective fuzzy optimization calculation
Authors: Xu Jing , ye Meiying 
Published: May 2021

Abstract
With the development of the social economy, the number and scale of construction projects are also growing. How to control construction project costs has become the key to investment and construction. Based on the multi-objective fuzzy optimization computing, the completed project investment data in the actual project progress is used for empirical analysis of a construction project using the cost prediction model.
Comparative Analysis of Hydration Expansion Performance of Desulfurized gypsum-baseda/β Gypsum
Authors: Zhang Jixiu , Zhang Ye , Miao Yuanchao , Duan Saihong 
Published: May 2021

Abstract
Gypsum has micro-expansion characteristic during the process of hydration and solidification, and there are certain differences in the hydration expansion characteristics of different types of hemihydrate gypsum. In this paper, by analysing the gypsum crystal morphology, particle size distribution, hydration heat, dimensional change rate, and morphology change of hydration products in the process of hydration process, the hydration expansion performance of α/β gypsum are compared and discussed. The results indicate there are differences in the hydration swelling mechanism between α-gypsum and β-gypsum. The expansion of gypsum is the result of the combined effect of the crystal transformation and the release hydration heat during the hydration process. The particle size distribution and the amount of hydration water added have a great influence on the expansion performance.
Effect of Hybrid Fiber on Early Mechanical Properties of High Performance Concrete
Authors: He Tusheng , Chen Qidong , Li Zaibo , Liu Yang , Zhao Sanyin , Zhao Xuguang 
Published: May 2021

Abstract
The early mechanical properties of hybrid fiber reinforced concrete were studied by orthogonal test, the factors of steel fiber content, polypropylene fiber content and length on compressive strength and splitting tensile strength of concrete for 3 d ages were investigated, the test results were analyzed by range analysis, variance analysis and performance index analysis. The results show that the hybrid fiber has a negative hybrid effect on the compressive strength of concrete for 3 days, a positive hybrid effect on the splitting tensile strength of concrete for 3 days. When the volume fraction of polypropylene fiber is 0.1%, the length is 12mm, and the volume fraction of steel fiber is 1.5%, the compressive strength of concrete is the largest. When the volume fraction of polypropylene fiber is 0.15%, the length is 18mm and the volume fraction of steel fiber is 1.5%, the splitting tensile strength of concrete is the largest.
Study on the Selection Principles of Building Sealant in AAC External Wall
Authors: Zhang Ye , Zhang Jixiu , Miao Yuanchao , Duan Saihong 
Published: May 2021

Abstract
With the vigorous development of prefabricated buildings in China, the maturity of assembly technology, the matching of materials and the professionalism of construction have become the focus of attention. As the most important lightweight wall enclosure material, the sealant for autoclaved aerated concrete (AAC) wall plays a major role in the joint sealing of the wall. In this paper, on the analysis of related standards and the application characteristics of sealants, the requirements of sealant for AAC external wall are discussed and summarized. The requirements include good compatibility and adhesion with the substrate, low modulus and high displacement ability, environmental protection, good weather resistance and paint ability (when there is painting demand for the joints).
Water expansion performance standard for cement stabilized phosphogypsum soil
Authors: Peng Bo , Zhang Jing , Peng Jing-wen 
Published: May 2021

Abstract
The application of cement stabilized phosphogypsum soil (CSPS) in highway engineering has great economic and social benefits. There are few corresponding classification standards for water swelling during long-term use and so a test method for water swelling of CSPS is designed. Unconfined compressive strength (UCS), dry shrinkage (DS), and temperature shrinkage (TS) of CSPS at three cement contents and eight phosphogypsum (PG) contents were measured. This paper analyzes the reasons for the poor early mechanical strength of CSPS. Based on the water expansion tests, ultimate expansion without load (δe) is proposed as the evaluation index for water expansion. Combined with the relationship between the shear strength of the CSPS after the termination of water expansion, δe, and PG content, a water swelling classification standard for CSPS is established. The results show that be is negatively correlated with cement content, and positively correlated with PG content. In combination with direct shear test results, CSPS is divided into mild water expansion (0 <δe ≤15), moderate water expansion (15 < δe ≤80), and severe water expansion (δe > 80).
Comparative study on properties of recycled concrete mixed with slag and polypropylene fiber/steel fiber
Authors: Fang Jinmiao , Zhi-yong Han , Qingyun Ge , Zhu Bian , Wenli Li 
Published: May 2021

Abstract
In order to study the effect of fiber and slag on the performance of high performance recycled aggregate concrete, polypropylene fiber/steel fiber and slag are selected as admixtures, in which fiber is used as admixture and slag is equivalent to replace cement content. The influence of recycled aggregate content, admixture formula and admixture on the mechanical and water absorption properties of high performance recycled concrete and its improvement effect were analyzed systematically. The results showed that when the slag is added, the early mechanical properties of concrete have little effect, the later is slightly improved, but the water absorption of concrete is improved significantly. Adding fiber can not only improve the compressive strength, splitting tensile strength and flexural tensile strength of high performance recycled concrete, but also significantly improve the water absorption properties. Fiber and slag composite modified material can bond concrete mixture into a whole and improve the density of the mixture.
Study on the interaction mechanism between deep displacement of soil and internal force of anchor cable under pile-anchor support system of ultra-deep foundation pit
Authors: Han J H , Wang J P , Gu C Y 
Published: May 2021

Abstract
Based on a concrete engineering example, the change law of soil deep displacement and internal force of anchor cable in the excavation process of foundation pit under pile and anchor support system is simulated by numerical analysis method, and compared with the measured results, and the synergistic action law of soil deep displacement and internal force of anchor cable is discussed. The comparison between the results of finite element numerical analysis and the field measurement shows that the two-dimensional finite element numerical analysis can reflect the variation law of the deep displacement of soil and the internal force of anchor cable in the field to some extent.
Study on properties and pore structure characteristics of cement-based materials with limestone powder
Authors: Xia Junying , Yu Bentian , Wang Huan , Han Baojian , Chen Yanfei , Xie Chao 
Published: May 2021

Abstract
In order to study the effect of limestone powder as an auxiliary cementing material replacing part of cement on the properties and pore structure of cement mortar, the working performance, mechanical properties and pore structure characteristics of cement mortar with 0%, 10%, 20% and 40% substitutions of limestone powder were tested. The experimental results show that with the increase of the amount of limestone powder, the fluidity of mortar increases continuously and the water retention also becomes better. The addition of limestone powder improves the workability of mortar, but with the increase of limestone powder, the compressive strength of mortar decreases continuously. The results of low field NMR show that the porosity of cement mortar increases firstly and then decreases with the increase of limestone powder content. Compared with the reference mortar, its porosity is improved to some extent, however the pore throat distribution indicates that the increase of porosity is caused by the increase of small pores between 0.01μm and 0.16μm. The harmful macropores between 0.16μm and 0.63μm in mortar are reduced, which indicate that the addition of limestone powder can effectively improve the pore diameter distribution of mortar.
Centrifugal Modeling of Geo-synthetics Reinforced Roadbed under Cyclic Loading Condition
Authors: Mu Taiping , Chen Tianyi , Qiu Zhixiong 
Published: May 2021

Abstract
The cyclic load of overload vehicles will cause uneven deformation of the roadbed, leading to serious safety accidents. Geo-synthetics can effectively restrict the roadbed as a type of reinforcement. However, it is not clear how to arrange geo-synthetics for a good balance between the economic benefits and sufficient reinforcement. A series of centrifuge model tests of geo-synthetics reinforced roadbed are carried out under the cyclic loads. The deformation and reinforcement effect are investigated by considering the different geo-synthetics spacing. The results show that geo-synthetics effectively restricts the roadbed deformation. The reinforcement effect of geo-synthetics decreases with the increase of depth along the loading center. The geo-synthetics reinforcement effect is enhanced by decreasing the geo-synthetics spacing. The cyclic loads only induce deformation within a limited zone in the roadbed. As the geo-synthetics spacing decreases, the depth of the deformation zone decreases while the horizontal width increases.
Application Research on Information Integration Technology of Bridge BIM Model Based on 2-D EBS Coding System
Authors: Sha Gaocen , Wang Hong , Men Guangyu , Guo Rui , Feng Yuchuan 
Published: May 2021

Abstract
In the trend of information technology, BIM Technology has been widely used in the design, construction and maintenance stages of bridge engineering activities with its own advantages. At present, BIM Technology has made further development to realize the bridge life cycle information. In view of the shortage of information carrier in the application of EBS in BIM life cycle, this paper proposes a 2-dimensional EBS coding system component decomposition coding system. The 2-D EBS coding system is composed of component information and subsidiary information. Through the practical application of Shapotou Yellow River Bridge in Ningxia, the possibility of 2-D EBS coding system in bridge life cycle information integration, exchange and storage is further verified. It provides a link role for bridge life cycle informatization, and has strong engineering practice significance.
Accuracy analysis of multi-baseline InSAR height inversion
Authors: Hao Yin Ying , Hui YuanZhi 
Published: May 2021

Abstract
Digital elevation model (DEM) is of great significance in commercial and scientific applications, and the accuracy of elevation inversion represents the quality of DEM. With reference to the height measurement accuracy formula of single-baseline interferometric SAR, the mathematical relations between elevation accuracy and platform height, lower viewing angle, target oblique distance, baseline strip number, baseline length and baseline roll angle are established, and the variation of elevation accuracy with system parameters (especially the number of base lines and baseline length) is quantitatively analyzed, and the optimal range of multi-baseline InSAR system parameters is obtained. It provides a theoretical basis for the optimal design of system parameters.
A modified partially averaged Navier-stokes model for the turbulent flows over a backward facing step
Authors: Ye W X , Miyagawa K , Luo X W 
Published: May 2021

Abstract
In current study, a partially averaged Navier-stokes model based on a modified SST k-ω model is proposed (MSST PANS) to predict the turbulent flows with flow separations, recirculation and reattachment. A benchmark case, turbulence flows over the backward facing step (Re=50000), is treated to evaluate the capacity of the MSST PANS model. Several other turbulence models, i.e., the standard k-ε model, SST k-ω model, the standard k-ε PANS (SKE PANS) model and SST k-ω PANS (SST PANS) model are also implemented for comparisons with some available experimental data. Results show that the MSST PANS model performs the closest results in predicting the reattachment length as well as the corner vortex. Furthermore, the MSST PANS model yields improved statistics on the skin frictions, pressures, velocity profiles together with Reynolds stresses. In contrast to the SST PANS models, the modifications on the eddy viscosity and ω equation with consideration of streamline curvature show promising in capturing the small-scale flow separations, recirculation and reattachments in some industrial applications.
Localization and characterization of rotating noise sources on axial fans by means of an irregularly shaped microphone array
Authors: Amoiridis O , Zamponi R , Zarri A , Christophe J , Schram C 
Published: May 2021

Abstract
Aerodynamic noise emitted by low-speed axial fans has been receiving increasing attention in various sectors of high societal impact, such as automotive and HVAC systems. In this framework, turbulence interaction, flow non-uniformities, trailing-edge boundary layer fluctuations and blade-tip leakages are different mechanisms generating aeroacoustic sources on the rotating blades and contributing to the overall emitted sound. An accurate localization of the sound sources on the surface of the blade is instrumental in separating and isolating these contributions and, therefore, in designing novel sound mitigation concepts. The main objective of this paper is to present an inexpensive and efficient way to isolate and quantify the noise generating mechanisms on rotating blades by means of a irregularly shaped microphone array. The technique is based on ROtating Source Identifier (ROSI) and has been implemented and validated at the von Karman Institute for Fluid Dynamics (VKI). Simulated benchmark datasets that refer to rotating point sources emitting white noise have been considered for the validation of the method. The accuracy in the source localization and in the source strength reconstruction has been evaluated for a fixed and a variable angular rate. Moreover, the algorithm implementation has been parallelized with the purpose of reducing its computational time, which represents the main drawback of ROSI. Finally, the developed technique has been applied to measure the noise sources generated by a forward-skewed subsonic axial fan operated at maximum efficiency. In this case, it has been possible to successfully localize and characterize the major noise sources on the blades. Although further investigation will be necessary to gain better insight into the topic, the present work constitutes an important step for a better understanding of the physical phenomena occurring in the noise generation of an axial fan.
Hybrid Overset-LES Simulations of Noise Reduction Concepts of Loaded Airfoils
Authors: Bernicke P , Akkermans R A D 
Published: May 2021

Abstract
The noise reduction potential of a loaded airfoil is investigated by means of a novel Overset-LES simulation method. This aerodynamic noise prediction tool solves the compressible Navier-Stokes equations, supplemented with a sub-filter-stress model, in perturbation form over a background flow. The such obtained noise sources are subsequently propagated with wave propagation equations to the far-field (e.g., with the Acoustic Perturbation Equations). This hybrid prediction method is applied to a noise reduction investigation of a loaded airfoil. For this purpose, two geometries are considered, i.e., a reference geometry and a modified geometry with a long-chord slat. The effect of the long-chord slat on the turbulent sound sources is investigated by mainly considering turbulence statistics in the slat cove and shear-layer reattachment location. Moreover, the acoustic far-field propagation revealed the influence of a long-chord slat on the directivity. The slat noise reduction primarily results from the combined effect of the less intense shear-layer instabilities and the larger distance between reattachment location and upper trailing-edge, rather than a shielding effect by the long-chord slat. The predicted noise reduction matches well with values reported in literature.
Identification of Noise Sources in a Realistic Turbofan Rotor Using Large Eddy Simulation
Authors: Kholodov P , Moreau S 
Published: May 2021

Abstract
Large Eddy Simulation (LES) is performed using the NASA Source Diagnostic Test database at approach conditions (62% of the design speed). The simulation is performed in a periodic domain containing one single blade. The aerodynamic and acoustic results are compared with the experiment. Ffowcs Williams and Hawkings’ (FWH) analogy is used to compute the far-field noise from the solid surface of the rotor blade. The analogy is computed for the full blade and for its tip region to see the contribution of the latter. The dynamic mode decomposition is performed at different iso-radii of the computational domain. The contribution of the tip region to the far-field noise is observed around the first blade passing frequency (2.8 kHz) and 4 kHz due to the mixing process of the leading-edge and tip vortices. The rest of the blade contributes more at frequencies above 7 kHz which corresponds to the trailing-edge noise. The high-amplitude modes are observed at 75% and 90% of the spanwise length. These modes contribute to the corresponding frequency humps in the far-field spectrum.
Noise from unmanned aerial vehicle contra-rotating propellers
Authors: McKay R. S. , Go S. T. , Jung S. , Kingan M. J. 
Published: May 2021

Abstract
This paper presents an analysis of the noise produced by contra-rotating propeller systems used on small unmanned aerial vehicles. Selected results from an extensive experimental campaign are presented. In these experiments a commercially available contra-rotating propeller with 2- and 3-blade propellers was statically tested in a large anechoic chamber. It was observed that the noise spectrum contained a large number of tones which occurred at the sum of integer multiples of the blade passing frequency of each propeller. These tones exhibit some interesting features including: the amplitude of the interaction tones decays rapidly with increasing propeller spacing; tones for which the azimuthal mode number is equal to zero generally have a dipole like radiation pattern radiating strongly along the propeller axis. This is in contrast to the tones at the blade-passing frequency which radiate strongly in the plane of the propeller. A simple theoretical model for predicting the tones produced by the contra-rotating propeller is presented and is used to explain some of the observed phenomena.
Lattice Boltzmann Simulation of Industrial Axial Fan Noise
Authors: Hayashi K , Nakaye S , Nishimura S 
Published: May 2021

Abstract
Noise simulation of an industrial axial fan has been conducted by implicit large-eddy simulation with Lattice Boltzmann simulation which is based on Cumulant Lattice Boltzmann method with wall model and diffuse-interface method for a moving boundary condition. Simulation results are compared with experimental results of a factory test of an industrial fan for a thermal power generation. The result shows a good agreement and overall value is within 3dB error.