High order schemes, which are widely used in DNS and LES, received increasing attention in recent years with a number of variants being developed. However most of these schemes…
Abstract
High order schemes, which are widely used in DNS and LES, received increasing attention in recent years with a number of variants being developed. However most of these schemes have difficulties in achieving high order accuracy near the boundary points. In order to solve this problem, the analytical discrete method (ADM) is proposed and presented in this paper. In addition, this method is convenient to construct the higher order WENO (weighted essentially non‐oscillatory) scheme. Application of the ADM‐WENO scheme to shock‐tube problems and compressible mixing flows has shown it is robust and accurate in both shock‐capturing and complex flow structures detection.
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Bifu Xiong, Siliang He, Jinguo Ge, Quantong Li, Chuan Hu, Haidong Yan and Yu-An Shen
This paper aims to examine the effects of bonding temperature, bonding time, bonding pressure and the presence of a Pt catalyst on the bonding strength of Cu/SB/P-Cu/SB/Cu joints…
Abstract
Purpose
This paper aims to examine the effects of bonding temperature, bonding time, bonding pressure and the presence of a Pt catalyst on the bonding strength of Cu/SB/P-Cu/SB/Cu joints by transient liquid phase bonding (TLPB).
Design/methodology/approach
TLPB is promising to assemble die-attaching packaging for power devices. In this study, porous Cu (P-Cu) foil with a distinctive porous structure and Sn-58Bi solder (SB) serve as the bonding materials for TLPB under a formic acid atmosphere (FA). The high surface area of P-Cu enables efficient diffusion of the liquid phase of SB, stimulating the wetting, spreading and formation of intermetallic compounds (IMCs).
Findings
The higher bonding temperature decreased strength due to the coarsening of IMCs. The longer bonding time reduced the bonding strength owing to the coarsened Bi and thickened IMC. Applying optimal bonding pressure improved bonding strength, whereas excessive pressure caused damage. The presence of a Pt catalyst enhanced bonding efficiency and strength by facilitating reduction–oxidation reactions and oxide film removal.
Originality/value
Overall, this study demonstrates the feasibility of low-temperature TLPB for Cu/SB/P-Cu/SB/Cu joints and provides insights into optimizing bonding strength for the interconnecting materials in the applications of power devices.
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The purpose of this study is to empirically explore the impact of government subsidies for the digital economy on corporate innovation. It aims to determine whether these…
Abstract
Purpose
The purpose of this study is to empirically explore the impact of government subsidies for the digital economy on corporate innovation. It aims to determine whether these subsidies promote innovation, and to examine the specific ways in which they inspire corporate innovation.
Design/methodology/approach
This study selects Chinese A-share listed companies during the period from 2007 to 2019 as the research object. It employs panel data to empirically examine the impact of government subsidies in the digital economy on corporate innovation.
Findings
The findings reveal that government subsidies for the digital economy effectively promote corporate innovation. They significantly increase the number and share of invention patents and improve the quality of corporate innovation. Moreover, it is noted that the positive impact is largely confined to non-state-owned enterprises, small firms and those in highly competitive markets.
Originality/value
The contribution of this paper lies in focusing on government subsidies in the digital economy, which is distinct from the general government subsidies in a broad sense.
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Xun Xu, Haidong Yu, Yunyong Li and Xinmin Lai
The structure stiffness is greatly affected by the fixture constraints during assembly due to the flexibility of large-scale thin-walled structures. The compliant deformation of…
Abstract
Purpose
The structure stiffness is greatly affected by the fixture constraints during assembly due to the flexibility of large-scale thin-walled structures. The compliant deformation of structures is usually not consistent for the non-uniform stiffness in various clamping schemes. The purpose of this paper is to investigate the correlation between the assembly quality and the clamping schemes of structures with various initial deviations and geometrical parameters, which is based on the proposed irregular quadrilateral plate element via absolute nodal coordinate formulation (ANCF).
Design/methodology/approach
Two typical clamping schemes are specified for the large-scale thin-walled structures. Two typical deviation modes are defined in both free and clamping states in the corresponding clamping schemes. The new irregular quadrilateral plate element via ANCF is validated to analyze the compliant deformation of assembled structures. The quasi-static force equilibrium equations are extended considering the factors of clamping constraints and geometric deviations.
Findings
The initial deviations and geometrical parameters strongly affect the assembly deviations of structures in two clamping schemes. The variation tendencies of assembly deviations are demonstrated in details with the circumferential clamping position and axial clamping position in two clamping schemes, providing guidance to optimize the fixture configuration. The assembly quality of structures with deviations can be improved by configuration synthesis of the clamping schemes.
Originality/value
Typical over-constraint clamping schemes and deviation modes in clamping states are defined for large-scale thin-walled structures. The plate element via ANCF is extended to analyze the assembly deviations of thin-walled structures in various clamping schemes. Based on the proposed theoretical model, the effects of clamping schemes and initial deviations on the deformation and assembly deviation propagation of structures are investigated.
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Jian Gao, Hao Wen, Zhiyuan Lin, Haidong Wu, Si Li, Xin Chen, Yun Chen and Yunbo He
Remanufacturing of worn blades with various defects normally requires processes such as scanning, regenerating a geometrical reference model, additive manufacturing (AM) through…
Abstract
Purpose
Remanufacturing of worn blades with various defects normally requires processes such as scanning, regenerating a geometrical reference model, additive manufacturing (AM) through laser cladding, adaptive machining and polishing and quality inspection. Unlike the manufacturing process of a new part, the most difficult problem for remanufacturing such a complex surface part is that the reference model adaptive to the worn part is no longer available or useful. The worn parts may suffer from geometrical deformation, distortion and other defects because of the effects of harsh operating conditions, thereby making their original computer aided design (CAD) models inadequate for the repair process. This paper aims to regenerate the geometric models for the worn parts, which is a key issue for implementing AM to build up the parts and adaptive machining to reform the parts. Unlike straight blades with similar cross sections, the tip geometry of the worn tip of a twist blade needs to be regenerated by a different method.
Design/methodology/approach
This paper proposes a surface extension algorithm for the reconstruction of a twist blade tip through the extremum parameterization of a B-spline basis function. Based on the cross sections of the scanned worn blade model, the given control points and knot vectors are firstly reconstructed into a B-spline curve D. After the extremum of each control point is calculated by extremum parameterization of a B-spline basis function, the unknown control points are calculated by substituting the extremum into the curve D. Once all control points are determined, the B-spline surface of the worn blade tip can be regenerated. Finally, the extension algorithm is implemented and validated with several examples.
Findings
The proposed algorithm was implemented and verified through the exampled blades. Through the extension algorithm, the tip geometry of the worn tip of a twist blade can be regenerated. This method solved a key problem for the repair of a twist blade tip. It provides an appropriate reference model for repairing worn blade tips through AM to build up the blade tip and adaptive machining/polishing processes to reform the blade geometry.
Research limitations/implications
The extension errors for different repair models are compared and analyzed. The authors found that there are several factors affecting the accuracy of the regenerated model. When the cross-section interval and the extension length are set properly, the restoration accuracy for the blade tip can be improved, which is acceptable for the repairing.
Practical implications
The lack of a reference geometric model for worn blades is a significant problem when implementing blade repair through AM and adaptive machining processes. Because the geometric reference model is unavailable for the repair process, reconstruction of the geometry of a worn blade tip is the first crucial step. The authors proposed a surface extension algorithm for the reconstruction of a twist blade tip. Through the implementation of the proposed algorithm, the blade tip model can be regenerated.
Social implications
Remanufacturing of worn blades with various defects is highly demeaned for the aerospace enterprises considering sustainable development. Unlike straight blades, repair of twist blades encountered a very difficult problem because the geometric reference model is unavailable for the repair processes. This paper proposed a different method to generate the reference model for the repair of a twist blade tip. With this model, repair of twist blades can be implemented through AM to build up the blade tip and adaptive machining to subtract the extra material.
Originality/value
The authors proposed a surface extension algorithm to reconstruct the geometric model for repair of twist blades.
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Yunyong Li, Yong Zhao, Haidong Yu and Xinmin Lai
A new deviation propagation model considering the form defects in compliant assembly process is proposed. The purpose of this paper is to analyze the deviation propagation by…
Abstract
Purpose
A new deviation propagation model considering the form defects in compliant assembly process is proposed. The purpose of this paper is to analyze the deviation propagation by using the basic deviation fields. In particular, each basic deviation field is defined with a generalized compliance matrix of part.
Design/methodology/approach
First, the form defects of parts may be decomposed into a linear combination of basic deviation fields, which are constructed by the eigen-decomposition of the structure stiffness of parts with ideal dimensions. Each basic deviation field is defined with a generalized compliance of part. Moreover, by analyzing the relationship between the basic deviation fields before and after assembling process, a new sensitive matrix is obtained in which each value expresses the correlation of a basic deviation field between the parts and the assembly.
Findings
This model may solve the deviation propagation problems of compliant assembly with considering form defects. Here, one case is used to illustrate the deviation propagation in the assembly process. The results indicate that the proposed method has higher accuracy than the method of influence coefficient when the entire deviation fields of parts are considered. Moreover, the numerical results with the proposed method basically agree with the experimental measurements.
Research limitations/implications
Owing to the hypothesis of linear superposition of basic deviation fields, the research in this paper is limited to the parts with linear elastic deformation. However, the entire form defects of parts are considered rather than the deviations of the local feature points. It may be extended to analyze the three-dimensional deviations of complex thin-walled parts.
Originality/value
A deviation propagation model considering parts form defects is developed to achieve more accurate predictions of assembly deviation by using the basic deviation fields.
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The purpose of this study was to investigate how financial literacy and investment experience impact cryptocurrency investment behavior and explore which factor is more…
Abstract
Purpose
The purpose of this study was to investigate how financial literacy and investment experience impact cryptocurrency investment behavior and explore which factor is more influential in cryptocurrency investment.
Design/methodology/approach
Using a sample of US individual investors from the 2018 National Financial Capability Study Investor Survey, a three-step hierarchical logistic regression was conducted following a model-comparison approach. In addition, a mediation analysis was conducted using the Karlson−Holm−Breen (KHB) method to further explore the mediating effect of investment experience between financial literacy and cryptocurrency investment.
Findings
This study found that while both financial literacy and investment experience were positively associated with investing in cryptocurrencies, investment experience was more influential in cryptocurrency investment. The findings also demonstrated that investment experience, especially risky asset holding, had a significant mediating effect between subjective financial knowledge and cryptocurrency investment behavior.
Practical implications
The findings of this study offer insight to researchers by providing a deeper understanding of the determinants of cryptocurrency investment in the United States. This study also provides detailed implications for financial institutions, financial professionals and policymakers to guide rational cryptocurrency investment behavior.
Originality/value
This study is one of the initial attempts to explore the determinant factors in cryptocurrency investment, an area that has rarely been studied in the literature.
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Shanhua Qian, Longfei Gong, Wei Wang, Zifeng Ni and Haidong Ren
This study aims to reduce the harm of industrial lubricants to consumers. Composite aluminum-based grease (CAG) was prepared, and medical-grade montmorillonite (M-MMT) was used to…
Abstract
Purpose
This study aims to reduce the harm of industrial lubricants to consumers. Composite aluminum-based grease (CAG) was prepared, and medical-grade montmorillonite (M-MMT) was used to improve the antiwear performance of the prepared grease.
Design/methodology/approach
The influence of the additive (M-MMT) on the tribological performance is mainly investigated using a ball-disc wear tester, and the wear scar surface about the disc was characterized by white light interferometer and electrochemical workstation. Moreover, the cell viability test was used to evaluate the safety of the grease.
Findings
The results indicated that for the grease containing 1.5% M-MMT, the average coefficient of friction was reduced by about 46% compared with the CAG, the wear volume of the disc reduced by about 74%. Moreover, CAG and 1.5% M-MMT-containing CAG were proved safety by means of the cell viability test.
Originality/value
The integral properties of CAG can be improved with the medical-grade materials as the additives, while ensuring the safety.
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The purpose of this paper is to explore the relationship between firm size, the nature of ownership and corporate social responsibility (CSR) performance in China and to figure…
Abstract
Purpose
The purpose of this paper is to explore the relationship between firm size, the nature of ownership and corporate social responsibility (CSR) performance in China and to figure out the reason that state-owned enterprises (SOEs) usually perform better in CSR activities than private enterprises.
Design/methodology/approach
The authors conducted two studies of CSR in China. In the first study, the authors developed and assessed a CSR measure; second study was to investigate the difference of CSR behavioral performance between SOEs and private enterprises.
Findings
The authors found that the differences in CSR performances between SOEs and private enterprises were not caused by the nature of ownership as most Chinese scholars used to believe. Actually, the differences came from the differences of firm size, which had been ignored in prior studies on factors influencing CSR performance. The size of SOEs is usually much larger than private enterprises, and larger enterprises often perform better in the field of CSR. In a word, the size rather than the nature of ownership is the main reason that CSR performances of SOEs are better than private enterprises.
Originality/value
Though many papers in China suggested that SOEs performed much better than private enterprises in CSR activities, the authors proved that this belief was a misunderstanding. It was found that SOEs were usually larger than private enterprises, which might have confused their efforts to find the real reason that SOEs and private enterprises perform differently in CSR. The authors also developed a measuring tool of CSR based on the Stakeholder Theory, which would be a new measurement tool for future studies, especially for emerging market economies and unlisted companies.
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Lini Zhang, Haidong Zhao and Brenda Cude
This study, which is based on the extended hierarchy of effects (HOE) model, aims to examine whether social media interactions with one or more luxury brands can affect consumers'…
Abstract
Purpose
This study, which is based on the extended hierarchy of effects (HOE) model, aims to examine whether social media interactions with one or more luxury brands can affect consumers' knowledge of, affection for and purchases of as well as loyalty to luxury fashion brands as a category.
Design/methodology/approach
SoJump (a leading data collection company in China) launched an online survey to collect data from Chinese luxury fashion brand consumers. Structural equation modeling (SEM) was conducted to analyze data from the random sample of 308 Chinese luxury fashion brand consumers.
Findings
The findings of this study demonstrated that social media interaction had direct positive influences on three stages of the luxury fashion brand decision-making process – knowledge, affection and loyalty – but not purchases. The results also empirically confirmed that consumers' response to social media interaction follows the cognition-affect-conation sequential process presented in the HOE model.
Practical implications
This study not only provides a new perspective for researchers to investigate the impacts of interactive social media marketing on purchase decision-making in the luxury fashion brand category but also underpins the importance of building interactive alliances for luxury brands to increase consumers' knowledge of, affection for, purchases in and loyalty to the luxury fashion brand category.
Originality/value
This study is among the first to investigate whether social media interactions with luxury fashion brands as a category influence consumers' knowledge of, affection for and loyalty to that category. In addition, this study is the first attempt to explore whether social media interactions can directly influence consumers' luxury fashion brand purchases.