Ruzhong Yan, Liaoyuan Wang and Shengze Wang
The purpose of this study is to reveal the influence law of pressure-equalizing grooves on aerostatic bearings and improve the static performance of bearings by optimizing the…
Abstract
Purpose
The purpose of this study is to reveal the influence law of pressure-equalizing grooves on aerostatic bearings and improve the static performance of bearings by optimizing the distribution form of grooves.
Design/methodology/approach
In view of two kinds of common restrictor distribution forms on the thrust surface, the linear and the rectangular, six kinds of pressure-equalizing groove schemes were proposed – the line-shape, the extended-shape, the S-shape, the oblong-shape, the X-shape and the reticular-shape. Based on the analysis of lubrication theory of the orifice-type aerostatic bearing, the numerical simulations of different bearings were carried out. The pressure distributions and static characteristic curves of different bearings were obtained.
Findings
The study reveals that the adoption of the pressure-equalizing grooves can substantially improve the load capacity and static stiffness of the bearing and make the bearing maintain a uniform stress, which enhances operating accuracy and life of the bearing. The superior function of the reticular-shape groove is highlighted.
Originality/value
The research results can effectively guide the optimization design of aerostatic bearings and provide a crucial technical reference for application of ultra-precision aerostatic supporting system.
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Ruzhong Yan, Liaoyuan Wang and Shengze Wang
The purpose of this paper is to study the mechanical properties of aerostatic guideway taking the structural deformation into account, and further improve the calculation method…
Abstract
Purpose
The purpose of this paper is to study the mechanical properties of aerostatic guideway taking the structural deformation into account, and further improve the calculation method of guideway.
Design/methodology/approach
A theoretical model of fluid-structure interaction for the numerical simulation was established and mechanical properties of the aerostatic guideway with porous restrictors were solved based on computational fluid dynamics. The deformation law of the guideway with different materials and gas-film thicknesses was revealed, and its static and dynamic characteristic curves were obtained.
Findings
The results indicate that ceramics as the material of guideways exhibit good applicability due to the small deformation, the quick dynamic response and the relatively light weight. The rational initial gas-film of guideway is recommended.
Originality/value
The present work can provide ideas for the design and optimization of aerostatic guideways.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2019-0288
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Liaoyuan Chen, Tianbiao Yu, Ying Chen and Wanshan Wang
The purpose of this paper is to improve the dimensional accuracy of inclined thin-walled parts fabricated by laser direct metal deposition (DMD) under an open-loop control system.
Abstract
Purpose
The purpose of this paper is to improve the dimensional accuracy of inclined thin-walled parts fabricated by laser direct metal deposition (DMD) under an open-loop control system.
Design/methodology/approach
In this study, a novel method of the adaptive slicing method and DMD process with feedback adjustment of deposition height has been developed to successively fabricate complex inclined thin-walled square tube elbow parts. The defocus amount was used as a variable to the matching between the deposition thickness and the adaptive slicing height.
Findings
The low relative error of dimensional accuracy between experimental and designed parts shows that the matching of the single-layer deposition thickness and the adaptive slicing height can be realized by optimizing the defocusing amount. The negative feedback of the thin-wall part height can be achieved when the defocus amount and the z-axis increment are less than deposition thickness. The improvement of dimensional accuracy of inclined thin-walled parts is also attributed to the optimized scanning strategy.
Practical implications
The slicing method and deposition process can provide technical guidance for other additive manufacturing (AM) systems to fabricate metal thin-walled parts with high dimensional accuracy because the feedback control of deposition height can be realized only by the optimized process.
Originality/value
This study provides a novel adaptive slice method and corresponding the deposition process, and expands the slicing method of AM metal parts.
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Xiangou Zhang, Yuexing Wang, Xiangyu Sun, Zejia Deng, Yingdong Pu, Ping Zhang, Zhiyong Huang and Quanfeng Zhou
Au stud bump bonding technology is an effective means to realize heterogeneous integration of commercial chips in the 2.5D electronic packaging. The purpose of this paper is to…
Abstract
Purpose
Au stud bump bonding technology is an effective means to realize heterogeneous integration of commercial chips in the 2.5D electronic packaging. The purpose of this paper is to study the long-term reliability of the Au stud bump treated by four different high temperature storage times (200°C for 0, 100, 200 and 300 h).
Design/methodology/approach
The bonding strength and the fracture behavior are investigated by chip shear test. The experiment is further studied by microstructural characterization approaches such as scanning electron microscope, energy dispersive spectrometer and so on.
Findings
It is recognized that there were mainly three typical fracture models during the chip shear test among all the Au stud bump samples treated by high temperature storage. For solder bump before aging, the fracture occurred at the interface between the Cu pad and the Au stud bump. As the aging time increased, the fracture mainly occurred inside the Au stud bump at 200°C for 100 and 200 h. When aging time increased to 300 h, it is found that the fracture transferred to the interface between the Au stud bump and the Al Pad.
Originality/value
In addition, the bonding strength also changed with the high temperature storage time increasing. The bonding strength does not change linearly with the high temperature storage time increasing but decreases first and then increases. The investigation shows that the formation of the intermetallic compounds because of the reaction between the Au and Al atoms plays a key role on the bonding strength and fracture behavior variation.
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Shi Zheng, Zhigang Wang and Cheryl Joy Wachenheim
The purpose of this paper is to investigate factors influencing intent to adopt unmanned aerial vehicles for use in agricultural operations in Jilin Province, China.
Abstract
Purpose
The purpose of this paper is to investigate factors influencing intent to adopt unmanned aerial vehicles for use in agricultural operations in Jilin Province, China.
Design/methodology/approach
This paper uses probit analysis to estimate the influence of factors on intent to adopt unmanned aerial vehicles for plant protection application operations in Jilin Province, China based on the Technology Acceptance Model.
Findings
UAV technology is acceptable to most participating farmers. Gender (male), agricultural income ratio, understanding of new technology, perceived ease-of-use and perceived usefulness have a positive relationship with farmers’ willingness to adopt UAVs.
Practical implications
For application, crop monitoring and other farm operations, UAVs have clear advantages. There remain challenges associated with the development of applicable technology and facilitating adoption among farmers. Understanding factors affecting adoption will contribute to the latter, and brings forth the following recommendations: conduct research on the cost effectiveness of UAVs for agriculture; accelerate development of the information service system; and increase financial support.
Originality/value
This paper is among the first to consider adoption intent among Chinese farmers of use of UAVs for agricultural operations.
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Wujuan Zhai, Florence Yean Yng Ling, Jiyong Ding and Zhuofu Wang
Megaprojects have large impact on the environment and stakeholders should take collective action to ensure that these projects are developed in a socially responsible manner…
Abstract
Purpose
Megaprojects have large impact on the environment and stakeholders should take collective action to ensure that these projects are developed in a socially responsible manner. Hitherto, it is not known whether group and subjective norms and social identity could compel stakeholders to take socially responsible collective actions in megaprojects. The aim of this study is to design and test a model to boost stakeholders' intention to take socially responsible collective action in the context of mega water transfer projects in China.
Design/methodology/approach
A quasi-experimental causal research design was adopted to establish cause–effect relationships among the dependent variable (we-intention) and independent variables (subjective norms, group norms, social identity and desire). This study adopts the belief–desire–intention model and social influence theory to empirically investigate how to boost the stakeholders' intention to participate in socially responsible collective action. An online questionnaire survey was conducted and data was collected from 365 respondents who were involved in mega water transfer projects in China. The partial least squares structural equation modeling technique was employed to analyze the data.
Findings
The results from partial least squares analyses indicate that the presence of subjective norms, group norms and social identity (collectively known as social influence process) could increase stakeholders' intention to take socially responsible collective action. In addition, the desire to be socially responsible also boosts stakeholders' intention to take collective action. Desire partially mediates the relationship between social influence process and intention to take socially responsible collective action.
Originality/value
This study adds to existing knowledge by discovering social influence process as an antecedent to taking socially responsible collective action in megaprojects. Strong group norms and subjective norms could propel stakeholders to be more socially responsible. The study also adds to knowledge by discovering that stakeholders' desire to fulfill social responsibility also leads them to take concrete actions. Implications and recommendations are provided on how to manipulate different types of social influence processes to facilitate stakeholders to adopt socially responsible collective action in the process of managing megaprojects.
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Xiaoxing Liang and Zhixiang Zhou
With the rapid economic growth and urbanization development, regional environmental problems have attracted increasing attention. The study on analyzing cities’ capacity on…
Abstract
Purpose
With the rapid economic growth and urbanization development, regional environmental problems have attracted increasing attention. The study on analyzing cities’ capacity on resource utilization and environmental protection is practically significant because of the industrial agglomeration in an urban area. This study aims to measure environmental efficiency of urban industrial water utilization by comparing input, output and undesirable outputs variables of cities.
Design/methodology/approach
This paper combines data envelopment analysis basic approach with regression to discover the environmental efficiency score of cities and their influence factors. A set of slack-based measure (SBM) model is constructed for calculating the environmental efficiency score by considering both desirable and unendurable outputs.
Findings
This paper analyzes the industrial water utilization efficiency for China from the city level by evaluating the performance for up to 200 mainland Chinese cities during 2012–2016 under SBM model. Then, 2C Tobit regression is used to measure the determining factors of industrial water utilization efficiency from the angle of natural, social, municipal and industrial structure factors. The empirical study results show huge room for improvement in industrial water utilization in China, while the average citizen efficiency scores maintain a level of about 0.5.
Originality/value
Significant differences exist in the regional efficiency in different cities in China. Per capita GDP, a total length of drainage pipe and whether the area is coastal or not have significant positive impacts on the water utilization efficiency, while the proportion of secondary industry to GDP has a significant negative influence. Specific recommendations are proposed based on the local industrial water utilization efficiency scores, such as improving urban infrastructure and adopting a more flexible water pricing system.