bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-dimensional horizontal visibility graph analysis of human brain aging on gray matter
Authors: Huang-Jing Ni , Ruo-Yu Du , Lei Liang , Ling-Ling Hua , Li-Hua Zhu , Jiao-Long Qin
Published: March 2023

Characterizing the trajectory of the healthy aging brain and exploring age-related brain structural changes can help deepen our understanding of the mechanism of brain aging. Currently, most structural magnetic resonance imaging literature explores brain aging merely from the perspective of morphological features, which cannot fully utilize the gray-scale values containing important intrinsic information about brain structure. In this study, we proposed to construct two-dimensional horizontal visibility graphs based on the pixel intensity values of the gray matter slices directly. Afterward, the normalized network structure entropy (NNSE) was introduced to quantify the overall heterogeneities of these graphs. The results demonstrated decreased between the NNSEs of gray matter and ages. Compared with the middle-aged and the elderly, the larger values of the NNSE in the young group may indicate the more homogeneous network structures, the smaller differences in importance between nodes, and thus a more powerful intrusion tolerance ability. In addition, the hub nodes of different adult age groups are primarily located in the precuneus, cingulate gyrus, superior temporal gyrus, inferior temporal gyrus, parahippocampal gyrus, insula, precentral gyrus, and postcentral gyrus. Our study can provide a new perspective for understanding and exploring the structural mechanism of brain aging.
Effects of collisional ion orbit loss on tokamak radial electric field and toroidal rotation in an L-mode plasma
Authors: Zhu Hongxuan , Stoltzfus-Dueck T. , Hager R. , Ku S. , Chang C.S.
Published: March 2023

Ion orbit loss has been used to model the formation of a strong negative radial electric field E

r
in the tokamak edge, as well as edge momentum transport and toroidal rotation. To quantitatively measure ion orbit loss, an orbit-flux formulation has been developed and numerically applied to the gyrokinetic particle-in-cell code XGC. We study collisional ion orbit loss in an axisymmetric DIII-D L-mode plasma using gyrokinetic ions and drift-kinetic electrons. Numerical simulations, where the plasma density and temperature profiles are maintained through neutral ionization and heating, show the formation of a quasisteady negative E

r
in the edge. We have measured a radially outgoing ion gyrocenter flux due to collisional scattering of ions into the loss orbits, which is balanced by the radially incoming ion gyrocenter flux from confined orbits on the collisional time scale. This suggests that collisional ion orbit loss can shift E

r
in the negative direction compared to that in plasmas without orbit loss. It is also found that collisional ion orbit loss can contribute to a radially outgoing (counter-current) toroidal-angular-momentum flux, which is not balanced by the toroidal-angular-momentum flux carried by ions on the confined orbits. Therefore, the edge toroidal rotation shifts in the co-current direction on the collisional time scale.
Modulation behaviour and possible existence criterion of geodesic acoustic modes in tokamak devices
Authors: Palermo F. , Conway G.D. , Poli E. , Roach C.M.
Published: March 2023

Geodesic acoustic modes (GAMs) represent the oscillating counterpart of zonal flow in tokamak plasma and can affect transport due to their interaction with turbulence eddies. GAMs have been observed in many experiments and modelled under different conditions, but because of their variety of characteristics, we do not yet have a complete picture of their dynamics. It has been demonstrated that optical methods can be efficiently used to describe and predict several characteristics of the GAM radial structures that can be interpreted as ‘waves’ propagating in the space-time. We exploit complex eikonal theories to investigate the behavior of GAMs that are commonly observed in experiments, and find that their periodic modulation and intermittency can be explained by the properties of the equilibrium temperature profile. Theoretical results obtained in this work are supported by gyrokinetic simulations for several equilibria. Implications for existence criteria and GAM dynamics in different plasma equilibrium conditions are discussed, with particular attention to the edge plasma in low and high confinement modes.
33Cl Spectroscopic Factors via the 32S(3He, d)33Cl One-Proton Transfer Reaction
Authors: Cinausero M , Dell’Aquila D , Lombardo I , Vigilante M , Barlini S , Bolzonella R , Bruno M , Buccola A , Cartuan S , Casini G , Cicerchia M , D’Andrea M , Degerlier M , Fabris D , Gasques L , Gramegna F , Lepine-Szily A , Mantovani G , Marchi T , Piantelli S , Rigato V , Scomparin L , Valdrè S
Published: March 2023

The structure of light-to-medium mass nuclei is crucial to understand exotic phenomena in nuclear structure, including the appearance of molecular effects in light nuclei and their impact in nuclear astrophysics. In this paper, a new experiment to probe one-proton spectroscopic factors of bound and unbound states in the sd-nucleus 33Cl is discussed. The experiment exploits the reaction 32S(3He, d)33Cl* at 9.68 MeV bombarding energy. This reaction is suitable to probe the single-particle structure of 33Cl states with respect to the population of 1d
3/2, 1f
7/2 and 2p
3/2 shells. Crucial aspects of the investigation are the use of an enriched, high-purity, 32S target and a new generation hodoscope with improved angular resolution, allowing to obtain high-precision angular distribution of the differential cross section in a broad angular range. Results are interpreted by means of finite-range DWBA and coupled-channel calculations.
Heavy-ion induced quasi-elastic reactions in view of the NUMEN project
Authors: Cavallaro M , Agodi C , Auerbach N , Bellone J I , Bijker R , Brischetto G A , Burrello S , Calabrese S , Cappuzzello F , Carbone D , Ciraldo I , Colonna M , De Gregorio G , Delaunay F , Ferreira J L , Fisichella M , Gambacurta D , García-Tecocoatzi H , Gargano A , Lay J A , Lenske H , Linares R , Lubian J , Santopinto E , Sgouros O , Soukeras V , Spatafora A , Torresi D
Published: March 2023

Double charge exchange (DCE) reactions induced by heavy ions and other direct reactions characterized by same projectile and target are crucial tools to access information relevant for neutrinoless double beta decay nuclear matrix elements. In this context the NUMEN project aims to investigate, for each system of interest, not only the DCE channel but also the whole set of reactions promoted by the same projectile/target interaction in the same experimental conditions and within the same theoretical framework. An example of the application of such a multi-channel approach is presented here.
Electron Scattering for Neutrino Physics at MAMI and MESA
Authors: Doria Luca
Published: March 2023

The groundbreaking discovery of neutrino oscillations represents a concrete indication of new physics and the measurement of the oscillation parameters has the potential to unlock new knowledge on the fundamental building blocks of matter. For measuring the neutrino properties to percent-level precision, an ambitious accelerator-based experimental program was started by two international collaborations: HyperK and DUNE. However, these experiments will only be able to achieve their unprecedented precision goal if our current knowledge of neutrino-nucleus interactions in the detectors is dramatically improved. In this contribution, we describe how experiments based on electron beams can provide key information to neutrino experiments, benchmarking theoretical models, improving simulations needed for a reliable extraction of the neutrino oscillation parameters, and decisively contribute to the success of next-generation neutrino experiments.
Gamow-Teller excitations in the Subtracted Second RPA approach
Authors: Gambacurta Danilo
Published: March 2023

The charge-exchange subtracted second random-phase approximation, based on Skyrme functionals, is employed to investigate the Gamow-Teller resonances in several nuclei, located in different regions of the nuclear chart. The amount of Gamow-Teller strength is considerably smaller than in other energy-density-functional based calculations and agrees better with the experimental data. These important results, obtained without any ad hoc quenching factors, are due to the inclusion of two-particle–two-hole configurations. Their density progressively increases with excitation energy, leading to a long high-energy tail in the spectrum. This result may have implications for the computation of nuclear matrix elements for neutrinoless double-beta decay in the same framework.
Direct measurement of the 13C(α,n)16O reaction in the Gamow window of the s-process nucleosynthesis
Authors: Ciani G.F. , Formicola A.
Published: March 2023

One of the main neutron sources for the astrophysical s process is the 13C(α,n)16O reaction, which takes place in thermally pulsing asymptotic giant branch (TP-AGB) stars at environmental temperature around 90 MK. To model the nucleosynthesis process connected with the reaction, it is important to know with high accuracy the cross section reaction in the energy window 240-150 keV, the so called Gamow window. At these sub-Coulomb energies, direct cross section measurements are severely affected by the low event rate and low signal-to-noise ratio. In this work, a new study of the astrophysical S(E)-factor for the 13C(α,n)16O reaction is presented.

In the framework of the LUNA scientific programme, a direct measurement of the absolute cross section of the 13C(α,n)16O reaction in an energy window from 300 keV down to 230 keV, significantly closer to the Gamow peak, has been performed. Lower uncertainties with respect to literature values are obtained allowing to reduce overall uncertainties on reaction rates calculation. Selected stellar models have been computed to estimate the impact of our revised reaction rate. For stars of nearly solar composition, we find sizeable variations of some isotopes, whose production is influenced by the activation of close-by branching points that are sensitive to the neutron density, in particular 60Fe, 205Pb and and 152Gd.
A + 2n compound nuclei and the unitary limit in nuclear physics
Authors: Georgoudis P E
Published: March 2023

This contribution discusses a new perception of the structure of compound nuclei by introducing intermediate states of the Feshbach formalism of nuclear reactions in the Interacting Boson Model of nuclear structure. The stake is to explore the manifestation of the unitary limit in heavy, even-even nuclei. Interactions that govern Feshbach resonances of cold and dilute atomic gases suggest the formulation of an IBM-compound Hamiltonian for scattering two neutrons (2n) from a heavy, even-even target (A). The solutions of the corresponding coupled channel equations host a 2n-IBM state resonance. It turns out that the unitary limit is measurable in a heavy A + 2n compound nucleus at low temperatures. That measurement is feasible through the fluctuations of the cross-sections that tune the 2n-A scattering length.
Experimental Investigation on the Failure Behavior of Single-Stiffened Composite Panels under Compressive Load
Authors: Yu Fei , Zhang Ru , Chen Xiangming , Deng Fanchen , Wang Zhe , Yuan Fei , Cheng Liping , Lin Guowei , Li Xinxiang
Published: March 2023

Whilst the thin-walled composite structures have been widely used to build the primary components in aircraft, Low-Velocity Impact (LVI) can cause severe intra-laminar and inter-laminar damage in the composite material, reducing the mechanical performance of these components. This paper presents an experimental study on the compressive failure behavior of a Single Hat-Stiffener Panel (SHSP) with two typical flaws, i.e., impact-induced damage and skin/stiffener debonding. LVI tests were performed to introduce the damage around the radius edge of the stiffener and the center of the flat skin panel, respectively, while the skin/stiffener debonding was introduced to the SHSP by artificially embedding a PTFE film at the skin/stiffener interface during autoclave curing. The impact energy to cause Barely Visible Impact Damage (BVID) was determined to be 22 J for the thin SHSP configuration. Whilst the considerable damage area was detected by the ultrasonic scan for the thick SHSP at an energy level of 35 J, the impact-induced indentation was not visually detectable (<0.35 mm), indicating a high impact resistance of this thick SHSP. Compression After Impact (CAI) results showed a significant reduction (59.1%) in the ultimate compressive strength of the SHSP when the impact location was on the stiffener compared to the pristine specimen. However, this reduction is less significant (34.7%) when the damage resulted from the same impact energy in the flat skin panel. In this study, the presence of skin/stiffener debonding does not adversely influence the compressive strength of the thick SHSP, while this debonding flaw appears to cause a minor reduction in the compressive strength of the thin SHSP.
Model-based Operation Safety Assessment for Civil Aircraft
Authors: Ma Biao
Published: March 2023

With the operation of China’s large aircraft, operational safety has become an important issue. The manufacturer uses operation data and design data to carry out safety assessments in the operation phase. Operation safety assessment evaluates whether the conclusion of the safety assessment is still valid and analyzes the safety margin of the aircraft in the operating environment. Model-based civil aircraft operation safety assessment method uses the model-based ideology to propose a technical method of operating safety assessment based on the failure propagation model. The relevant practice also shows that this method is effective and can improve efficiency and accuracy.
Research Progress and Prospect of Satellite Constellation Optimization Design
Authors: Zhao Shuailong , Wang Yaru , Zhang Yasheng , Zheng Kaiyuan
Published: March 2023

Satellite constellation optimization has gradually developed from simple single-objective optimization to complex multi-objective optimization. Among them, the high-dimensional and multi-objective dynamic optimization problem poses a great challenge to the performance of the algorithm. To improve convergence speed and optimization performance, researchers continue to improve modern optimization algorithms. Firstly, the construction process of the optimization model is reviewed. The model takes the coverage performance, network performance, and system cost as objective functions or constraints. Secondly, the general forms of multi-objective constellation optimization design models under various constraints are given, and the applications of modern optimization algorithms such as genetic algorithm (GA), non-dominated sorting genetic algorithm (NSGA-2), multi-objective particle swarm optimization algorithm (MOPSO), differential evolution algorithm (DE) in different constellation design tasks, as well as their characteristics and development trends are introduced. Finally, it is pointed out that in the era of vigorous development of Leo mega-constellations, the combination of modern optimization algorithms and machine learning is the future research direction to solve high-dimensional and multi-objective dynamic optimization problems.
Investigation of Mixing Characteristics of the Transverse Jet in a Supersonic Combustor at Low Mach Inflow Condition
Authors: Wang Yi , Zhang Lin , Liang Jianhan
Published: March 2023

LES is used in the present work to simulate and unfold unsteady flow dynamics and mixing characteristics in a cavity-based supersonic combustor at low Mach numbers. In the combustor, a transverse jet is injected ahead of the cavity. Two inflow Mach numbers (Ma=1.2 and Ma=2.5) are numerically investigated. Fine instantaneous and average mixing flow structures are well identified and analyzed by LES. The mixing performance is also studied and compared. The simulation results show that penetration is dominated by jet/freestream momentum flux ratio, even though the inflow Mach number varies. It is also demonstrated that for a jet at low Mach inflow, a higher coefficient of pressure is attained. While around the jet location, a much higher peak of the mixing vorticity efficiency is obtained for low Mach inflow, which is of fundamental importance to the near-field mixing.
Method and Experiment Study of the Array Shape Calibration for Underwater Vertical Line Arrays
Authors: Li Xuegang , Wu Shuyou , Su Shengli , Ding Lan , Jiang Guoqing
Published: March 2023

Vertical line arrays have been widely used in underwater target location and noise measurement, and the attitude and shape of the vertical array have a significant influence on detection accuracy. The paper presents an array shape calibration method for underwater vertical acoustic array-based measurement systems. Firstly, a standard acoustic source was used to transmit underwater acoustic signals at a certain distance from the acoustic array, and the target location based on the received data of the acoustic array was estimated concerning distance and depth to obtain the two-dimensional ambiguity function of the depth and distance of the array. Then, the ambiguity function was used to calculate the center depth and the inclination angle of the vertical acoustic array and to further obtain the shape and location information of the acoustic array. Finally, a lake experiment study was carried out. The results showed that the calibrated array shape was in good agreement with the actual location, and the sound source location estimated by using the calibrated array shape was consistent with the actual sound source location, thereby effectively reducing the impact on the measurement accuracy due to the inclination of the measurement system under the influence of water current.
Sound Quality Improvement of Dynamic Loudspeaker by Material Selection of Diaphragm
Authors: Dong Gengyue
Published: March 2023

In terms of sound quality, mechanical stability, and cost, the moving coil speaker is exceptional to the moving iron and electrostatic speaker. The diaphragm in the speaker is crucial in reproducing the sound wave from the electrical signal input. The materials of the diaphragm should be both rigid and lightweight. However, there are few quantitative studies on the selection of diaphragm materials. Connecting the equation of mass and the deflection of a circular plate yields a performance index that maximizes Young’s Modulus and minimizes the density. A line graph in logarithmic can be generated from the index to select materials from various categories in the Ashby plot provided by the Granta CES Edupack software. The chosen materials would be simulated in COMSOL and their sound pressure level plots would be analyzed based on the numerical solution. The Ashby plot and the numerical solutions by COMSOL have indicated that paper is the best material among the selected materials with the most stable frequency response in the mid-range frequency range, a high-performance index, and a low price per unit volume.
Analysis of 5 MW Blade Two-Way Fluid-Structure Interaction Characteristics
Authors: Lin Xihan , Liu Jiang , Jiang Weiting , Fu Zaiguo
Published: March 2023

A CFD-CSD coupled method was employed to establish an aeroelastic model of the NREL 5 MW wind turbine. The two-way fluid-structure interaction (FSI) simulation was carried out for this aeroelastic model. The response curves of blade tip flapwise, edgewise, and torsional deformation under normal operating conditions was obtained. The results show that the blade deformation shows a trend of increasing and then decreasing from the cut-in wind speed to the cut-out wind speed with the rise in wind speed. The maximum deformation appears in the vicinity of rated working conditions. Furthermore, the difference in aerodynamic performance between two-way FSI and one-way FSI has been studied to reveal the influence of the aeroelastic effect on performance. The two-way FSI that considers the blade deformation causes significant periodic fluctuations in the torque and thrust curves, with a maximum deviation of 3.75% in the average torque at 20 m/s. Therefore, the two-way FSI that introduces the aeroelastic effect can predict the aerodynamic performance more accurately.
Study on the Tribological Properties of Polymer Interface and the Mapping Mechanism of Friction Noise in a Wide Temperature Range
Authors: Cheng Ganlin , Guo Fei , Jia Xiaohong
Published: March 2023

In order to study the tribological properties and frictional noise mapping mechanism of polymer interface at a wide temperature range, tribological and frictional noise acquisition tests were carried out on a Ball-on-Three-Plates Tribology Accessory. The friction coefficient and noise signal data sets were collected for 15 minutes from the friction surfaces of polytetrafluoroethylene and 0Cr18Ni9 austenitic steel pairs at six temperatures and three constant loading-speed contact points in a wide temperature range of -150°C-25°C. The wear rate of the polymer was measured and the wear state of the polymer interface was studied by field emission environmental scanning electron microscopy (SEM). Based on the analysis of the time-frequency domain characteristics of friction noise and the qualitative mapping relationship between the wide-temperature domain tribological properties and friction noise, the theoretical and experimental basis is provided for establishing online early warning monitoring of the tribological performance of polymer-metal friction pairs based on the time-frequency domain characteristics of friction noise.
Effects of structural elasticity on the flow-induced cavity tone in water
Authors: Zhang Wenwen
Published: March 2023

Measurement of the flow-induced tones of cavities with three different structural elasticity was conducted in the water tunnel. The frequency and amplitude of the cavity tones varied with the water flow velocity are present and discussed. In addition, the modal jump phenomenon of flow-induced cavities for both elastic cavities and rigid cavities is compared and discussed. The influence law of structural elasticity on the characteristics of flow-induced tones in water cavities in the amplitude-frequency domain is analyzed.
Numerical Simulation for Nonlinear Interaction between an Attached Air Bubble and Nearby Oscillating Bubble
Authors: Jiang Mingzuo , Wang Jiaxia
Published: March 2023

The numerical simulations of a non-spherical evolution of pulsating bubble interacting with a stationary air bubble attached to a fixed structure were performed by using the three-dimensional boundary integral method which is based on the mirror image method to simplify the processing of the numerical model. Validation of the code is presented by comparison of numerical predictions with laboratory experimental data obtained by our previous research. Complex phenomena are observed such as three kinds of bubble jet forms: upward bubble jet, bubble splitting phenomenon, and downward bubble jet. The present simulations provide insight into the interesting bubble jetting phenomena in detail, including bubble splitting, jet away from the plate, and bubble shedding.
Numerical Simulation of Particle Filtration by Rectangular Fibres within a Parallel and Staggered Array
Authors: Yue Shixian
Published: March 2023

In this research, two-dimensional numerical simulation is used to examine the filtration performance of rectangular fiber filters. Ansys Fluent is employed to obtain the stable flow field distribution and the DPM model is used to calculate the particle trajectories in the flow field. The effect of pertinent factors such as fiber arrangement, particle-to-fiber diameter ratio, and Stokes number on the performance of rectangular fiber filters are analyzed. The simulation results indicate that both the parallel and staggered arrays of rectangular fibers have a significant influence on the capture efficiency and pressure drop. At the same flow velocity, the pressure drop of the fibers with a parallel array is lower than that of the staggered array fiber model. The capture efficiency of the staggered array model and the parallel array model increases with the increase of the ratio of particle to fiber diameter and the Stokes number. When the interception and inertial impaction mechanisms domiant, the filter with a staggered fiber array structure performs batter than the parallel array in terms of capture efficiency. The research results can provide a theoretical basis for the structure optimization and design of the air filter with multi-layer fiber.
Semi-supervised Learning Method for Source Range Estimation in Shallow Water
Authors: Li Lebo , Gong Fusheng , Liu Shijing
Published: March 2023

Data-driven machine learning methods in recent years have shown great vitality in underwater acoustic, especially in the localization of underwater sound sources. Meanwhile, there exists a great difficulty in the acquisition and processing of underwater acoustic data, which caused the lack of label data. This paper proposes a two-step semi-supervised learning-based range estimation method for shallow ocean sound sources, which utilizes semi-supervised learning in deep learning to alleviate the problem of limited access to underwater acoustic label data and relatively abundant unlabelled data in practical scenarios. The performance of the method has been validated on SWellEx-96 experiment data.
Study on the Self-Pressurization Laws of Cryogenic Liquid Krypton Tank for the Electric Propulsion System
Authors: Chen Ji Dong , Zhu Jian Bing , Zhao Ji Peng , Gu Sen Dong , Yu Bin , Yuan Yu Qi
Published: March 2023

To meet the application requirements of zero boil-off storage of cryogenic liquid krypton propellant in the process of completing deep space exploration missions by electric propulsion system, it is important to study the thermodynamic changes in cryogenic liquid krypton tanks under different environments. The gas phase and liquid phase material model of krypton working fluid, the gas-liquid phase change model at the interface layers, and the heat transfer process between the wall and the internal fluid are established by ANSYS-Fluent. The energy source term, gas phase, liquid phase mass source term, and phase change saturation temperature in the liquid krypton cryogenic tank are defined. This paper’s three influencing factors of gravity, initial liquid filling rate, and wall heat leakage are simulated and analysed. The results show that: (1) The self-pressurization rate significantly rises as the wall heat flux rises, and the gas-liquid interface drops less quickly. The pressure and temperature in the tank are also increasing at the same liquid level. (2) In the normal gravity environment, the bigger the filling rate, the lower the corresponding self-pressurization rate. (3) In the process of variable gravity, the gas pressurization rate in the cryogenic liquid krypton tank falls with the decrease of gravity.
Numerical Calculation of Hydrodynamic Characteristics of Individuals in Coral Nurseries
Authors: Liu Can , Dong Zhiyong , Pan Yun
Published: March 2023

Coral nurseries play a critical role in solving the technical and ecological problems that hinder the large-scale and long-term culture of coral populations, which has become an effective tool for the coral culture and the restoration of coral reefs. We need to conduct a profound study of the hydrodynamic characteristics of individuals in coral nurseries to ensure that the coral nurseries achieve long-term, industrialized, and batch coral cultivation. In this paper, the calcified coral skeletons of Acropora cervicornis are selected, followed by refined statistical analysis of the characteristic dimensions of individual corals to calculate the average density, and fitted equations for the horizontal projected area and volume. In addition, we also analyze the force of the individual coral, which lays a foundation for studying the hydrodynamic characteristics of corals under wave action.
First-Principles Calculations of Elasticity Properties of AgW20 Alloy
Authors: Liu Jide , Du Xiaoming , Wang Xue , Xie Ming , Li Jinguo , Zhao Shangqiang , Zhou Yizhou , Zhang Qiao , Fang Jiheng
Published: March 2023

In this paper, the first-principles calculations based on DFT were employd to investigate the elasticity characteristics of AgW20 alloy. The elasticity constants of the single crystals are calculated using the finite strain method and Voigt – Reuss – Hill (VRH) approach. The universal anisortropic index (AU
), shear anisortropic index, orientation dependency of Young’s modulus, bulk modulus were used to characterize elasticity anisortropy behaviors. The calculated elasticity properties of AgW20 alloy show a remarkable elasticity anisortropy for AgW20 alloy.
Study on Interfacial Effects on Thermal, Mechanical and Fluorescent Properties for SrTiO3-SrCeO3 Composites
Authors: Qu Liu , Wan Rui , Zhao Yanjie , Wang Yu
Published: March 2023

Combining different phases in composite materials introduces interfaces that control the microstructure as well as functional and structural properties. This work focused on designing thermodynamically compatible SrTiO3-SrCeO3 with low thermal conductivity and up-conversion photoluminescence. Using a one-pot solid-state reaction method, SrTiO3-SrCeO3 composites have been synthesized with high-temperature stability, low thermal conductivity, and ideal mechanical and photoluminescence properties. Due to the interfaces between cubic and orthorhombic structures that could enhance the phonon scattering, the thermal conductivity was significantly decreased, while the hardness was maintained and satisfied by the mixing law. The photoluminescence of SrTiO3-SrCeO3 exhibited green, blue and purple bands with an up-conversion fluorescence at room temperature.
Study on the Hydrogen Precipitation Performance of Nanofiber Aerogel-based Platinum-carbon Catalysts
Authors: Yu Haidan , Liu Yitao
Published: March 2023

Clean energy development is particularly important in the context of increasing environmental pollution caused by fossil energy consumption. In this paper, a carbon aerogel-loaded platinum (Pt/CNF As) catalyst prepared by freeze-drying and combined with sodium borohydride reduction can be used in a hydrogen evolution reaction (HER) to produce the most promising clean energy source and hydrogen energy. The plastic deformation is only 16% after 1000 compression cycles at 50% strain. In addition, compared with commercial Pt/C catalysts, Pt/CNF As eliminates the complicated process of working electrode preparation without reducing electrocatalytic activity and has an overpotential of only 40 mV (10 m A/cm2) and an active area of 124 mF/cm2.
Study on the Bearing Capacity of Stringer of Large Civil Aircraft Composite Fuselage after Impact Damage
Authors: Wu Yuzhen , Liu Fu
Published: March 2023

This paper analyzes the post-impact pressure loss test data of eight test configurations of composite fuselage hat-type stringers and measures each composite stringer’s residual compressive strength. It compares the bearing capacity and failure strain of different configurations of stringers with and without BVID initial impact damage. Based on the test data and analysis, the optimal configuration of the stringer is selected, which plays a guiding role in the structural design of composite panels.
Preparation and Performance of a New Type of Large-head Cutting Pick with Bimetallic Composite
Authors: Liu Shuang , Zhao Yingfan , Gao Jing , Yan Zelin , Li Tieshuai , Tong Weiping
Published: March 2023

In this paper, a new type of pick with a large size head is produced by a low-temperature bimetallic composite. The pick head is composed of 60 mm long high chromium cast iron, and the pick handle is 20# steel. They are connected by nickel-based alloy powder. The size of the bonding interface observed by SEM is approximately 1.3 mm. The pick head is mainly composed of M7C3 and M2C compounds with high wear resistance to bear the wear resistance of the pick. The pick handle with outstanding toughness bears the impact of picks. It is also worth mentioning that the impact toughness of the sample reaches 62 J/cm2 and the shear strength is 208 MPa.The hardness of the handle is about 325HV, and the pick head hardness is about 935HV. The hardness gradually increases from the pick handle to the pick head.
Dislocation hardening coupling between hard matrix and soft zones in a dual-phase heterostructured material
Authors: Li Zhongkai , Liu Chunming , Liu Yujie
Published: March 2023

Strain hardening coupling between hard and soft zones is still not well understood in heterostructured materials. Here we report the coupling of dislocation hardening between hard iron matrix and soft copper zones in heterostructured Fe-40Cu dual-phase materials. Dislocation hardening is the predominant hardening mechanism in the Fe-40Cu materials, as dislocations dominate plastic deformation in both iron and copper. Low-temperature annealing kept highly deformed iron matrix strong and inductile but softened copper zones by promoting recrystallization in them. This raised plastic incompatibility and strain partitioning between iron matrix and copper zones during deformation. As a result, dislocations accumulated dramatically in copper zones but barely in the iron matrix. Copper zones produced high dislocation hardening to compensate for the low one of the iron matrix, raising the total strain hardening of the heterostructured Fe-40Cu materials. Lowering the plastic incompatibility between the iron matrix and copper zones weakened the strain partitioning between them and consequently depressed the dislocation hardening of copper zones. The role that copper zones played turned from producing high dislocation hardening to stabilizing the plastic deformation of heterostructured Fe-40Cu materials at the high strain level.
Screening of critical dangerous parts of Pi-shaped pipe in the corrosive environment
Authors: Lao Xingsheng , Liu Yong , Dai Chunhui
Published: March 2023

In order to accurately predict the key dangerous parts of the polygonal pressure pipeline in a corrosive environment, based on the stress fatigue theory, a stainless steel pipeline damage calculation model coupled with the coupling of fatigue and corrosion is established, and the cold and operating conditions are carried out for the polygonal pressure pipeline. The analysis of stress and damage fields shows that the fatigue life of the square-shaped pipeline is reduced from 9225 to 42 years after the influence of the stress concentration factor of pitting corrosion. Based on the results of the damage analysis, by defining the dangerous concentration parameters, it is predicted that the key dangerous parts of the zigzag pressure pipeline are mainly the elbow and the long side abdomen. The greater the dangerous concentration parameter is, the more concentrated the dangerous parts are. When the dangerous concentration parameter is greater than 0.5, the elbow of the pipe shoulder and the long side joint are not critical dangerous parts anymore.
Nickel Catalysts Supported on Ce
x
Sm
y
Zr1−x−y
O2-δ
Complex for CO2 Methanation and its Kinetic Analysis
Authors: Ye Jichao , Zhang Hanbing , Hu Xinwei , Zhang Lei , Wang Lina , Wang Hong
Published: March 2023

CO2 methanation shows advantages in Power-to-Gas technologies using renewable energy. In this article, Sm doped Ce
x
Sm
y
Zr1−x−y
O2-δ
complex is prepared using a one-pot hydrolysis method and is used as support for the Ru-Ni catalyst. The CO2 methanation activity at high temperature, GHSV, and thermal stability is tested. The results show that Sm doping is unfavorable for low-temperature methanation activity, but improves the thermal stability with Sm doping amount of 10 mol%. The Sm doping significantly enhances the performance at high temperatures (>400 °C ) and high GHSV (> 10000 h−1). Five reaction rate equations with different adsorption expressions are applied for kinetic analysis. Low activation energies ranging between 50.1 kJ/mol and 53.2 kJ/mol are observed for different models, which are lower than reported Ni-based catalysts. The equation considering both CO2 and H2O adsorption achieves the best-fitting results.
Analysis of Contact Characteristics of Rough Surface/Microporous For Flat Friction Pair
Authors: Li Zhenhua , Ahmat Mutellip , Zhang Quanyi , Zhou Huafeng
Published: March 2023

The rough surface has serious friction, wear and thermal damage during the sliding friction process in engineering applications, which leads to the failure of the friction pair. The rough surface contact is simplified into a rough surface with fractal properties and an ideal plane. The interaction between the asperities of the contacting body and the coupling effect of frictional heat flow at the frictional interface is considered. The impact of contact pressure and temperature rise between microporous model and non porous model on rough surface was compared, as well as the impact of Sa on the area, contact pressure and temperature rise of the friction pair. The results show that in the process of uniform sliding friction, when the asperities pass through the micropores, the asperities are embedded in the edge of the micropores so that the peak contact pressure increases, cutting occurs, and the deformation is affected by the interaction between the micropores and the asperities. The position of the highest pressure point is not fixed due to the deformation of the asperity, which improves the force of the asperity, and the micro-hole reduces the contact zone, thereby reducing the contact of the asperity and the pressure extreme point and reducing the pressure.Micropores reduce the temperature and enhance the wear condition of the end face. Small surface roughness can decrease the risk of end face wear.
In-situ Observation of High-temperature Phase Transformation of Ti-6Al-4V Titanium Alloy
Authors: Zhu Qiangqiang , Yang Xingdi , Lan Huifang , Li Jianping , Zhang Tianxing
Published: March 2023

As a typical dual-phase titanium alloy, Ti-6Al-4V has a complex phase transformation process, which is sensitive to temperature parameters and difficult to control its microstructure. To further master the law of phase transformation of Ti-6Al-4V titanium alloy and make a reasonable heat treatment system, different heat treatment systems in β single-phase region and (α+β) two-phase region were made for Ti-6Al-4V titanium alloy, and the phase transformation process and microstructure growth rate of different heat treatment processes were studied by high-temperature confocal microscope. At 1050 °C and 1200 °C in the β single-phase region, the β grain size increases with the prolongation of the holding time and the increase of the holding temperature. The tissue growth rate of the α phase was higher than 1200°C in the cooling process after 1050°C incubation, which was 2.88 μm/s. Based on the heat preservation in the single-phase region, the second heat preservation was carried out for the two-phase region of Ti-6Al-4V titanium alloy at 850 °C and 900 °C. The study found that when the holding temperature was 850°C, the fastest growth rate of the α phase was 4.64 μm/s, which was greater than 3.29 μm/s when the holding temperature was 900°C.
The Effect of Nickel Content on Phase Transition Characteristics of Ni-rich Fe-Ni Elastocaloric Refrigeration Alloys
Authors: An Junyu , Shi Yongjun , Li Xianfa , Chen Jiaxian , Wang Shaowei
Published: March 2023

In order to examine the impact of Ni content on the phase transition properties of Ni-rich Fe-Ni elastocaloric refrigeration alloys, the mechanical alloying (AM) and powder metallurgy (PM) technologies were used to create the Fe-Ni alloys.The results show that similar to the Ni-lacked Fe-Ni alloys, the phase transition characteristics varied with the different of Ni content and displayed various trends. Besides, it was found that the phase change enthalpy reached 44.43J/g when the Ni content was 50% (at%), which was about 1.3 times of Ni-lacked Fe14.6Ni (at%) alloy. In addition, different from the BCC structure with crystal space group of IM-3M (225) of Ni-lacked Fe-Ni alloy, Ni-rich Fe-Ni elastocaloric refrigeration alloys presented the FCC structure with crystal space group of FM-3M (225). This study provides an experimental reference for the preparation and application of Ni-rich Fe-Ni elastocaloric refrigeration content.
Design of an integrated CO2 methanation system with CO2 capture from flue gas and H2 production from water electrolysis
Authors: Ye Jichao , Zhang Hanbing , Hu Xinwei , Zhang Lei , Wang Lina , Wang Hong , Li Wenying , Wu Kejing
Published: March 2023

As one of the important Power to X technologies, CO2 methanation realizes the storage of green hydrogen and the emission reduction of flue gas CO2. In this study, process modeling was applied for CO2 methanation coupled with CO2 capture and water electrolysis. Aspen Plus and HYSYS models of 400 kW water electrolysis were set up for integration. The heat exchange network and the reaction temperature and catalyst usage of two methanation reactors are optimized. The effects of step-wise evolution of H2 flow on stream flows and reactors are also studied. The results show a system energy efficiency of 42.3% using a high-temperature solid oxide electrolysis cell (SOEC) and 30% monoethanolamide solution (MEA). The heat-exchange network significantly improves the efficiency to 61.5%. Optimizing two-stage methanation reactors realizes 98% CO2 conversion at 10018 h-1 gas hourly space velocity. The optimized reaction temperatures are 390 and 325 °C, respectively. The Aspen HYSYS dynamic modeling shows that the flows reach stability within 10 min under 1 kmol/h step-wise evolution of H2 flow. Longer time is required to approach the stability of the methanation reactor. Sharp evolutions of H2 flow cause higher amplitudes and a longer time to reach stability. The H2 flow lower than 35% of the initial value would result in the unstable behavior of the methanation reactor.
Design of a CNC Incremental Forming Machine with a tiltable structure
Authors: Chen Runhao , Xu Chun
Published: March 2023

In view of the existing incremental forming machine, there is a problem that the tool needs to be replaced when machining parts with different degrees of sidewall concavity. The incremental forming machine with a tiltable cutter was designed, and the feasibility of a cutter tilting structure was discussed. The forming results show that the tiltable structure meets the design requirements.
Research on the Chemical Mechanical Polishing Process of Aluminum Alloy Wafers with Acidic Slurry
Authors: Song Xiaoming , Zhao Shicheng , Zhang Renjie
Published: March 2023

Aluminum alloy has low density, good thermal conductivity, and low resistivity, which has been widely used in the fields of the defense industry, aerospace, and machinery manufacturing. As technology advances, there is a growing demand for high-precision parts and green processing. In this paper, a green chemical mechanical polishing (CMP) slurry for aluminum alloy is developed to optimize the rotational speed and pressure and improve the quality of polished aluminum alloy surface. The influence of CMP slurry composition on the quality of aluminum alloy surface and its mechanism are analyzed. Orthogonal experiments and single-factor experiments are used to investigate the effects of CMP slurry composition and process parameters on the surface quality of polished aluminum alloy. A green chemical mechanical polishing slurry consisting of deionized water, 6 wt.% SiO2, 2 wt.% H2O2, and citric acid to adjust pH=3 was proposed, with the pressure of 24 kPa and rotational speed of 90 r/min. After the CMP of aluminum alloy, surface roughness was reduced from 45.587 nm to 0.876 nm in the scan range of 70 μm × 50 μm. The mechanism was analyzed by X-ray photoelectron spectroscopy (XPS).
Sliding Mode Control of Vehicle Semi-active Suspension System Based on Magnetorheological Damper
Authors: Tang Tianyu , Sha Shujing , Pan Chenhao , Li Hang
Published: March 2023

Given the fact that the passive suspension of the vehicle cannot adapt to the changing road excitation and replace conventional suspension with damping-adjustable semi-active suspension, based on the 1/4 vehicle model, sliding mode controllers are designed for two different error vectors respectively, and the simulation is carried out through Matlab/Simulink. The results show that the semi-active suspension controller can effectively improve the stability and safety of the vehicle when driving.
Design and optimization of a half-wavelength ultrasonic bone scalpel
Authors: Chen Jian , Chen Feng
Published: March 2023

Compared with traditional orthopedic surgical instruments, the ultrasonic bone scalpel (UBS) has obvious advantages in both safety and effectiveness. Based on the structure of the sandwich piezoelectric transducer, a design of half-wavelength UBS with a longitudinal vibration frequency of 22.5 kHz is proposed in this study. Firstly, the dimensions of each component of the UBS are calculated by the transmission matrix method, the initial design is verified by modal analysis, and the error is optimized by the response surface method. Then the harmonic response analysis is used to calculate the UBS’s tip amplitude, impedance and stress distribution. In addition, the influence of bolt pre-tightening force on the vibration characteristics of the UBS is analyzed. When the bolt pre-tightening force is 50-90MPa, the vibration performance of the UBS is stable, and the tip amplitude is large, which provides a reference for selecting appropriate tightening torque when the UBS is assembled. Finally, the bone-cutting experiment shows that the UBS has good cutting performance.
Design of a Shield Tail Clearance Measuring Sensor for a Shield Machine
Authors: Zhou Zheng , Liu Xiaolong , Li Wei , Sun Weiwei
Published: March 2023

To improve the measurement accuracy and judge the distance between shield segments and shield tail accurately, the online monitoring technology of shield tail clearance was studied. Firstly, a sensor that can be used for shield tail clearance measurement was designed, and its key parts were selected. Secondly, the characteristics of the key parts were simulated to verify their feasibility. Finally, the monitoring principle was analyzed
Study of dynamic wedging performance of the multi-shape sprag clutch
Authors: Yu Hao , Zhao Yongqiang , Xue Yuan , Cao Kai , Wu Xuemei
Published: March 2023

The dynamic contact parameters such as contact force, contact stress and rotational speed fluctuate with time during the actual operation of a sprag clutch. To this end, ANSYS LS-DYNA is applied to simulate the dynamics of various types of sprag clutches with different wedge surfaces to obtain the curves of speed, contact force, and windup angle of each component during operation with time. The dynamic wedging performance of the all-phase type and the PCE (positive continuous engagement) type clutch is compared and analyzed, and the effect of the change of contact angle on the dynamic wedging performance of the sprag clutch with logarithmic and Archimedean spirals is investigated, and the dynamic wedging performance of the three types of sprag clutches is compared and analyzed to guide the design of multi-faceted sprag clutches.
Sintering optimization of high nitrogen nickel free austenitic stainless steel prepared by Metal Injection Molding
Authors: Zou Liming , Liu Ruiyang , Su Zaijun , Gao Jixiang , Li Liejun
Published: March 2023

High nitrogen and nickel free austenitic (HNNFA) stainless steel prepared by powder metallurgy has become a research hotspot because of solving nickel precipitation and saving cost. In this paper, metal injection molding (MIM)method was used to prepare such kinds of steel. The effect of sintering parameters such as sintering temperature, holding time, and nitriding pressure on the density, shrinkage rate, and nitrogen content of austenitic stainless steel was systematically evaluated by an orthogonal experiment to obtain the optimum sintering parameters. When the sintering temperature is 1200°C, the holding time is 6 h, and the nitriding pressure is 1100 mbar, the sample possesses a higher density (7.52g/cm3) and nitrogen content (0.76%). The matrix of stainless steel is austenite after nitriding sintering.