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30 results on '"Zhang, Shuohua"'

3. Surface morphologies and corresponding hardness evolution during nanoscratching

Author

Zhang, Shuohua, Guo, Xiaoguang, Jin, Zhuji, Kang, Renke, Guo, Dongming, and Tang, William C

Subjects
Surface morphology, Scratching hardness, Ploughing hardness, Nano-scratch
Abstract

Machining surface topography is a key factor affecting the properties of optical materials.It is generally accepted that the fracture mode tends to dominate practical concerns onmachined parts and the elastic recovery area decreases with the increase of normal load.However, material removal rate is low for ductile zone processing of brittle materials. In thiscase, pile-up and elastic recovery are key factors for surface quality. In this study, an accuratescratching and ploughing hardness model with consideration of both pile-up and elasticrecovery was established based on a series of continuous and constant nanoscratch tests.The hardness evolution mechanism under different nanoscratch deformation modes wasthen investigated. It was found that, in different modes, hardness values exhibited differentcharacteristics due to the change of elastic recovery rate and the intersection of elastic andplastic states. Further, the mapping relationship between hardness dispersion and surfacemorphology characteristics was also investigated. The results indicated that high degree ofhardness dispersion usually corresponded to modes I and II while stable hardness valuerepresented a steady plastic stage. Based on the intrinsic relationship between evolution ofhardness and deformation modes, predicting hardness distribution by in-situ testing dataand then adjusting deformation mode in real time would be helpful in optimizing surfacequality.

Published
2020

12. Subnanoscale Ion Beam Modification-Assisted Smoothing of Heterostructure Surfaces

Author

Zhang, Shuohua, Guo, Xiaoguang, Jin, Zhuji, Kang, Renke, Tang, William C., and Gao, Shang

Abstract

Glass ceramic (GC) is the most promising material for objective lenses for extreme ultraviolet lithography that must meet the subnanometer precision, which is characterized by low values of high spatial frequency surface roughness (HSFR). However, the HSFR of GC is typically degraded during ion beam figuring (IBF). Herein, a developed method for constructing molecular dynamics (MD) models of GC was presented, and the formation mechanisms of surface morphologies were investigated. The results indicated that the generation of the dot-like microstructure was the result of the difference in the erosion rate caused by the difference in the intrinsic properties between ceramic phases (CPs) and glass phases (GPs). Further, the difference in the microstructure of the IBF surface under different beam angles was mainly caused by the difference in the two types of sputtering. Quantum mechanical calculations showed that the presence of interstitial atoms would result in electron rearrangement and that the electron localization can lead to a reduction in CP stability. To obtain a homogeneous surface, the effects of beam parameters on the heterogeneous surface were systematically investigated based on the proposed MD model. Then, a novel ion beam modification (IBM) method was proposed and demonstrated by TEM and GIXRD. The range of ion beam smoothing parameters that could effectively converge the HSFR of the modified surface was determined through numerous experiments. Using the optimized beam parameters, an ultrathin homogeneous modified surface within 3 nm was obtained. The HSFR of GC smoothed by ion beam modification-assisted smoothing (IBMS) dropped from 0.348 to 0.090 nm, a 74% reduction. These research results offer a deeper understanding of the morphology formation mechanisms of the GC surfaces involved in ion beam processing and may point to a new approach for achieving ultrasmooth heterostructure surfaces down to the subnanometer scale.

Published
2024
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20. Roller–rail parameters on the transverse vibration characteristics of super-high-speed elevators

Author

Shunxin Cao, Shuai Qiao, Cong Dongsheng, Zhang Shuohua, Mingxiao Dong, and Ruijun Zhang

Subjects
Elevator, business.industry, Mechanical Engineering, media_common.quotation_subject, 020302 automobile design & engineering, 02 engineering and technology, Structural engineering, Computer Science::Other, Computer Science::Robotics, 020303 mechanical engineering & transports, 0203 mechanical engineering, Transverse vibration, Eccentricity (behavior), business, Geology, media_common
Abstract

Interaction and wear between wheel and rail become increasingly serious with the increase in elevator speed and load. Uneven roller surface, eccentricity of rollers, and the looseness of rail brackets result in serious vibration problems of high-speed and super-high-speed elevators. Therefore, the forced vibration differential equation representing elevator guide rails is established based on Bernoulli–Euler theory, and the vibration equation of the elevator guide shoes and the car is constructed using the Darren Bell principle. Then, the coupled vibration model of guide rail, guide shoes, and car can be obtained using the relationship of force and relative displacement among these components. The roller–rail parameters are introduced into the established coupled vibration model using the model equivalent method. Then, the influence of roller–rail parameters on the horizontal vibration of super-high-speed elevator cars is investigated. Roller eccentricity and the vibration acceleration of the car present a linear correlation, with the amplitude of the car vibration acceleration increasing with the eccentricity of the roller. A nonlinear relationship exists between the surface roughness of the roller and the vibration acceleration of the car. Increased continuous loosening of the guide rail results in severe vibration of the car at the loose position of the support.

Published
2019

26. The analysis of the structural parameters on dynamic characteristics of the guide rail–guide shoe–car coupling system

Author

Ruijun Zhang, Qin He, Cong Dongsheng, and Zhang Shuohua

Subjects
Elevator, business.industry, Computer science, Mechanical Engineering, 020101 civil engineering, 02 engineering and technology, Structural engineering, Elevator system, Displacement (vector), 0201 civil engineering, ComputingMilieux_GENERAL, Vibration, 020303 mechanical engineering & transports, 0203 mechanical engineering, Bending stiffness, Coupling system, business, Integral method
Abstract

Guide rails are important part of the elevator guide system, which is significant to its dynamic characteristics that influence the vibration of the elevator system. In this study, the researchers set up a guide rail, guide shoe and car coupling system model which is based on the interaction relationship between guide rail, guide shoe and car. The influence of the three parameters such as the length, weight per unit length and the bending stiffness on the dynamic characteristics of the guide rail is analyzed by applying above model, using the step-by-step integration integral method under the discrete variables. The results showed that weight per unit length affects the quiver of the guide rail. The bending stiffness of the guide rail mainly affects the vibration displacement, the length, which has a significant influence on the vibration displacement and the quiver of the guide rail. The results reveal the inherent law between the structural parameters and the dynamic characteristics, which will provide theoretical guidance for the manufacture and selection of the guide rail and the design of the elevator.

Published
2018

30. Exploration of China's net CO 2 emissions evolutionary pathways by 2060 in the context of carbon neutrality.

Author

Li W, Zhang S, and Lu C

Subjects
China, Climate, Coal, Urbanization, Carbon Dioxide analysis, Carbon Sequestration
Abstract

In the context of global climate governance, as the biggest carbon emitter, China bears momentous responsibility for mitigating emissions. Especially after the carbon neutrality target is proposed, it is urgent for China to seek a feasible pathway to achieve net-zero carbon dioxide (CO 2 ) emissions by 2060. With the aims of exploring the net-zero emission pathways, an integrated prediction model incorporating the extreme learning machine (ELM) network, the Aquila optimizer (AO) technique, and the Elastic Net (EN) regression method is constructed. Then the prediction model is employed to project CO 2 emissions and forest carbon sinks during 2021-2060 under the nine designed scenarios. The simulation results reveal that China has the potential to achieve net-zero CO 2 emissions by 2060 under the combined effects of reducing emissions and increasing forest carbon sinks. Specifically, the total CO 2 emissions will be peaked at 11441 million tons CO 2 (MtCO 2 ) in 2029. The post-peak carbon reduction rate should be 8% per year, and the average annual forest carbon sink is required to be 209.45 TgC/year during 2021-2060. In addition, in accordance with the optimal carbon neutrality pathway, the GDP per capita growth rate should be maintained at 5.5% during the period of 2021-2030, China's urbanization rate should be increased to 72% in 2030, and the total energy consumption should be limited to a peak value of 6000 million tons of coal equivalent (Mtce) in 2030., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Published
2022
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