Xiaoqing Ni, Liang Zhang, Wenheng Wu, Dexiang Zhu, Decheng Kong, Chaofang Dong and Guoliang Zhu
Laser melting deposition (LMD) is an advanced additive manufacturing (AM) technology without powder waste, and nickel-based alloys with different Nb contents were created one-time…
Abstract
Purpose
Laser melting deposition (LMD) is an advanced additive manufacturing (AM) technology without powder waste, and nickel-based alloys with different Nb contents were created one-time by adjusting the ratio of mixed powders via a dual-feed system. Here, the authors provide a systematic report on the effects of the Nb content on the microstructure, Laves phase segregation and mechanical properties of as-received LMD nickel-based alloys. The effects of the Nb content on the microstructure, precipitation evolution and mechanical properties of the subsequent heat-treated LMD samples are also discussed in this paper.
Design/methodology/approach
Thus, the present research aims to obtain a better understanding of the effect of Nb content on the microstructural and mechanical properties of the as-received LMD Inconel 718 alloys through high-throughput sample fabrication. The microstructures were characterized by scanning electron microscopy and energy-dispersive spectroscopy, electron back-scattered diffraction and transmission electron microscopy methods. The mechanical properties were obtained from compressive tests and nano-indentation tests. Electrochemical tests, including electrochemical impedance spectroscopy and potentiodynamic polarizations, were carried out to evaluate the durability of the Inconel 718 alloys. Results can provide a factual basis for future applications of the functionally graded by AM technology.
Findings
The grain size of the as-received LMD Inconel 718 alloys decreased with the Nb content. The Laves phase distribution at the macro level was relatively uniform and the Laves phase exhibited a 1.5-fold nano-hardness compared with the matrix. The strength improvement for the as-received LMD Inconel 718 alloys with Nb content was attributed to grain refinement and enhancement of the Laves phase in terms of both hardness and content. Meanwhile, the corrosion resistance increased with the increase of the Nb content, especially for the pitting potential, which was attributed to the optimization of carbide precipitates due to the strong affinity between niobium and carbon.
Originality/value
The results provide a factual basis for the Nb content effect in LMD nickel-based alloys, and this method can greatly promote the development of new materials. The authors believe that this study makes a significant contribution to the literature and is suitable for publication.
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Yujing Ni, Qiong Li, Xiaoqing Li and Jun Zou
This chapter provides a synthesis of the research project which investigated whether or not the most recent mathematics curriculum reform has reached the classroom and influenced…
Abstract
This chapter provides a synthesis of the research project which investigated whether or not the most recent mathematics curriculum reform has reached the classroom and influenced classroom practice and student learning in the mainland China. Three types of evidence for change as a result of the curriculum reform were examined. These included the beliefs and perceptions of teachers about learning and teaching mathematics, the cognitive features of learning tasks and of classroom interaction that were implemented in classroom, and student learning outcomes. Two groups of elementary math teachers and their students participated in the study. One group had participated in the reform implementation in classroom for several years, and the other group had used the conventional curriculum when the project was conducted in 2005. About 150 videotaped class sessions were analyzed from 58 classrooms of the two groups. Survey methods were used to probe the changes in the beliefs and perceptions of teachers about teaching and learning mathematics. The student learning outcomes were assessed for three times with multiple measures of mathematics achievement. Findings of the project provide the converging evidence that the curriculum reform has resulted in some of the expected changes. Reform teachers were more likely to hold a dynamic view of mathematics and to indicate the importance to provide students the learning opportunity to hypothesize, to proof, and to communicate in learning mathematics. The reform classrooms used more learning tasks with higher cognitive demands. The teachers in the reform classrooms asked more questions that required students to describe procedures leading to their answers and the students in the reform classrooms raised more questions in learning mathematics. Students of the reform classrooms showed to have achieved a relatively more balanced development in different cognitive areas of mathematics achievement.
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Tiedan Huang and Alexander W. Wiseman
Tingting Qi's chapter titled, “Moving toward Decentralization? Changing Education Governance in China After 1985,” provides the historical and policy context for the volume. This…
Abstract
Tingting Qi's chapter titled, “Moving toward Decentralization? Changing Education Governance in China After 1985,” provides the historical and policy context for the volume. This chapter integrates the post-1978 Chinese educational reforms into the socioeconomic context of China. The special contribution of this chapter is that it explores the complexity of educational decentralization in China through an in-depth analysis of changes in education finance, administration, and curriculum. Qi reviews prior studies, government documents, laws, and regulations related to Chinese education reform since 1978 within the context of education decentralization in China. Qi also demonstrates that China's educational policy reforms are moving China toward “centralized decentralization” because decentralization is driven by a common, centralized national goal of economic modernization. The chapter presents evidence that “centralized decentralization” is a strategic maneuver that maintains centralized control while providing the reform legitimacy of decentralization. By focusing on decentralization as the core of Chinese educational policy reforms, this chapter situates the following chapters within the social, cultural, and political context of post-1978 China.
Alexander W. Wiseman and Tiedan Huang
As China's educational policy and reforms continue to evolve and adjust to shifting social, economic, and political conditions, this chapter provides a template for conceptually…
Abstract
As China's educational policy and reforms continue to evolve and adjust to shifting social, economic, and political conditions, this chapter provides a template for conceptually framing education research on and in China. To do so this chapter first identifies focus areas in comparative education research related to China, which reflect researcher perspective, perceived advantage, and demonstrated resistance to these educational policy reforms. The authors develop a conceptual framework for comparatively understanding education research on and in China, which focuses on the intersection of comparative education themes, institutional change agents or methods, and Chinese educational reform topics. This conceptual framework specifically accounts for overlap, complexity, and the evolving nature of educational policy reform in China. This chapter concludes by emphasizing the importance of comparative education researchers, national policymakers, and consumers of the research using new data and methods as they become available to continue to revise understandings of Chinese educational policy and reform.
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Xiaoqing Feng, Wen Wen, Yun Ke and Ying He
This study aims to examine whether a firm's demand for high-quality auditors is influenced by multiple large shareholders (MLS). As one type of ownership structure, MLS have…
Abstract
Purpose
This study aims to examine whether a firm's demand for high-quality auditors is influenced by multiple large shareholders (MLS). As one type of ownership structure, MLS have gained popularity in China recently and have different types of large shareholders, including large institutional shareholder, large foreign shareholder and large state shareholder. The authors also examine whether different types of MLS have heterogeneous impacts on appointing high-quality auditors.
Design/methodology/approach
With a sample of 27,131 firm-year observations from Chinese public companies from 2003 to 2018, the authors use multivariate regressions to examine the effect of MLS on auditor choice. Heckman two-stage analysis, a firm fixed effects model, propensity score matching and difference-in-differences test are used as robustness checks.
Findings
This paper finds that the presence and power of MLS increase the likelihood of appointing high-quality auditors. With regard to the types of MLS, large institutional shareholders and foreign shareholders have significant positive effects on appointing high-quality auditors, while the presence of state-owned large shareholders has no effect on auditor choice. Further analyses reveal that the positive effect of MLS on high-quality auditor choice is more pronounced in firms with severe agency problems and information asymmetry. Taken together, these results suggest that MLS play a monitoring role by demanding high-quality auditors.
Originality/value
This paper contributes to the literature on the determinants of auditor choice. While prior studies primarily focus on the impact of concentrated ownership structure, corporate governance and the pressure from stakeholders on auditor choice, this paper complements the literature by providing evidence from the heterogeneous effects of different types MLS. This paper also extends the literature on the consequences of MLS from the perspective of auditor choice.
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In order to solve the current imbalance of academic resources within the discipline, this article builds a three-dimensional talent evaluation model based on the…
Abstract
Purpose
In order to solve the current imbalance of academic resources within the discipline, this article builds a three-dimensional talent evaluation model based on the topic–author–citation based on the z index and proposes the ZAS index to evaluate scholars on different research topics within the discipline.
Design/methodology/approach
Based on the sample data of the CSSCI journals in the discipline of physical education in the past five years, the keywords were classified into 13 categories of research topics including female sports. The ZAS index of scholars on topic of female sports and so on was calculated, and quantitative indexes such as h index p index and z index were calculated. Comparative analysis of the evaluation effect was performed.
Findings
It is found that compared with the h index and p index, the z index achieves a better balance between the quantity, quality and citation distribution of scholars' results and effectively recognizes that the citation quality is higher and the number of citations of each paper is more balanced. In addition, compared to the z index, this article is based on a ZAS index model with an improved three-dimensional topic–author–citation relationship in research fields such as female sports.
Originality/value
It can identify some outstanding scholars who are engaged in small-scale or emerging topic research such as female sports and are excellent in different research areas. Talents create an objective and fair evaluation environment. At the same time, the ranking ability of ZAS indicators in the evaluation of talents is the strongest, and it is expected to be used in practical evaluations.
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Xiaoqing Li, Ziyu Chen and Chao Ma
The purpose of this paper is to achieve stable grasping and dexterous in-hand manipulation, the control of the multi-fingered robotic hand is a difficult problem as the hand has…
Abstract
Purpose
The purpose of this paper is to achieve stable grasping and dexterous in-hand manipulation, the control of the multi-fingered robotic hand is a difficult problem as the hand has many degrees of freedom with various grasp configurations.
Design/methodology/approach
To achieve this goal, a novel object-level impedance control framework with optimized grasp force and grasp quality is proposed for multi-fingered robotic hand grasping and in-hand manipulation. The minimal grasp force optimization aims to achieve stable grasping satisfying friction cone constraint while keeping appropriate contact forces without damage to the object. With the optimized grasp quality function, optimal grasp quality can be obtained by dynamically sliding on the object from initial grasp configuration to final grasp configuration. By the proposed controller, the in-hand manipulation of the grasped object can be achieved with compliance to the environment force. The control performance of the closed-loop robotic system is guaranteed by appropriately choosing the design parameters as proved by a Lyapunove function.
Findings
Simulations are conducted to validate the efficiency and performance of the proposed controller with a three-fingered robotic hand.
Originality/value
This paper presents a method for robotic optimal grasping and in-hand manipulation with a compliant controller. It may inspire other related researchers and has great potential for practical usage in a widespread of robot applications.
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Yuqing He, Xintian Liu and Xiaoqing Wang
This study aims to build a global environmental quality protection convention to jointly address the problems of environmental pollution governance worldwide.
Abstract
Purpose
This study aims to build a global environmental quality protection convention to jointly address the problems of environmental pollution governance worldwide.
Design/methodology/approach
From the perspective of environmental pollution of the air, ocean, forest, water and solid waste, the authors summarize the main important measures and mechanisms of environmental pollution governance in various countries.
Findings
The results indicate that management research on biodiversity and natural resources must be strengthened, the relationship between economic development and environmental quality management needs to be balanced, the comparative study of domestic and international environmental governance theories and practices should be strengthened, empirical and applied research on environmental governance needs to be focused on, and complete system research on environmental governance and management should be explored. In the future, further strengthening environmental awareness, addressing environmental pollution and managing environmental quality are necessary.
Originality/value
The environment is the foundation of human survival and development. With the development of economy, contradictions between human and natural environment (e.g. air, ocean, forest and water) have become prominent. Environmental pollution governance cannot only help address existing environmental problems but also solve economic problems of various countries. The prerequisite for sustainable development is to lay a solid foundation for the coordinated development of economic growth and pollution management.
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Chentong Chen is an undergraduate at Nanjing Normal University studying law and English. She has research interests in education policy, education assessment and evaluation, and…
Abstract
Chentong Chen is an undergraduate at Nanjing Normal University studying law and English. She has research interests in education policy, education assessment and evaluation, and child development. She is currently working on two research projects: policy issues related to the college entrance exam in China, and theories and practice of preschool assessment in the U.S.