Sen Jiang, Hua Ji, Tianhao Wang, Donglin Feng and Qian Li
The shapes of surface textures have been designed to control the leakage of mechanical seals in recent years. The purpose of this paper is to demonstrate the influence of…
Abstract
Purpose
The shapes of surface textures have been designed to control the leakage of mechanical seals in recent years. The purpose of this paper is to demonstrate the influence of geometric properties of elliptical dimples on the leakage rate.
Design/methodology/approach
A new geometric feature point is expressed using an analytical solution to locate the high-pressure zones. Furthermore, a numerical model of the three-dimensional flow field for the mechanical seal with elliptical dimples is developed using ANSYS Fluent to demonstrate the influencing mechanism.
Findings
The location of the proposed geometric converging point coincides with the maximum pressure point under different orientation angles. An inward flow on the leakage section observed from the simulation results is responsible for decreasing the leakage rate.
Originality/value
The influencing mechanism of the elliptical dimple on the leakage rate is demonstrated, which can facilitate the design of surface textures.
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Xiaojing Feng, Bin Cui, Yaxiong Liu, Lianggang Li, Xiaojun Shi and Xiaodong Zhang
The purpose of this paper is to solve the problems of poor mechanical properties, high surface roughness and waste support materials of thin-walled parts fabricated by…
Abstract
Purpose
The purpose of this paper is to solve the problems of poor mechanical properties, high surface roughness and waste support materials of thin-walled parts fabricated by flat-layered additive manufacturing process.
Design/methodology/approach
This paper proposes a curved-layered material extrusion modeling process with a five-axis motion mechanism. This process has advantages of the platform rotating, non-support printing and three-dimensional printing path. First, the authors present a curved-layered algorithm by offsetting the bottom surface into a series of conformal surfaces and a toolpath generation algorithm based on the geodesic distance field in each conformal surface. Second, they introduce a parallel five-axis printing machine consisting of a printing head fixed on a delta-type manipulator and a rotary platform on a spherical parallel machine.
Findings
Mechanical experiments show the failure force of the five-axis printed samples is 153% higher than that of the three-axis printed samples. Forming experiments show that the surface roughness significantly decreases from 42.09 to 18.31 µm, and in addition, the material consumption reduces by 42.90%. These data indicate the curved-layered algorithm and five-axis motion mechanism in this paper could effectively improve mechanical properties and the surface roughness of thin-walled parts, and realize non-support printing. These methods also have reference value for other additive manufacturing processes.
Originality/value
Previous researchers mostly focus on printing simple shapes such as arch or “T”-like shape. In contrast, this study sets out to explore the algorithm and benefits of modeling thin-walled parts by a five-axis machine. Several validated models would allow comparability in five-axis printing.
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Rebeca Cordero-Gutiérrez and Libia Santos-Requejo
The purpose of this paper is to analyze the underlying differences in the intention to participate in online commercial experiments through the social network considering users’…
Abstract
Purpose
The purpose of this paper is to analyze the underlying differences in the intention to participate in online commercial experiments through the social network considering users’ gender and age.
Design/methodology/approach
The model of this paper uses two relevant variables, trust and attitude, to test the behavioral intention. There were 269 data sets from social network’s users. Factorial analysis and linear regression were used in the analysis of the data obtained to investigate the differences in gender and age in the intention to participate in online commercial experiments.
Findings
The results of this paper show that there exist differences among women and men, and among youthers and adults. Women and youthers are the most desirable groups to conduct commercial experiments through social networks.
Research limitations/implications
From the point of view of the academics, this paper increases the knowledge of social network’s possibilities as a marketing tool.
Practical implications
This study and its conclusions are relevant for entrepreneurs in any field who want to reach their customers through a horizontal social network because they can improve the online experiments’ profit. Entrepreneurs can know and understand their customers better, taking into account their wishes, tastes and interests through when participating in a commercial experiment.
Originality/value
This paper describes the possibilities that social networks like Facebook offer entrepreneurs to know the intention of users to participate in an online commercial experiment. Moreover, the differences in gender and age allow in adapting the contents of the online commercial experiments to get better results. In addition, this research contributes to the investigation in the possibilities of social networks as marketing tools.
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Abstract
Purpose
This paper aims to review policy innovations in China for addressing the graduate unemployment crisis that has been created by the expansion of higher education in the past decade.
Design/methodology/approach
The authors draw on government documents, research findings, and mass media reports to highlight the key measures of the Chinese government to alleviate the over‐education problem and to improve college graduates' employment prospects.
Findings
The review describes government efforts both at the institutional level to enhance student employability and at the national level to create alternative employment channels. The Chinese experiences show that the challenges posed by the graduate employment crisis may turn out to be a new opportunity to reform higher education in order to better address the needs unique to a country's own society.
Social implications
The review of the Chinese case will inspire policy makers in other countries to seek alternative routes for the development of their own higher education.
Originality/value
This is the first study of its kind to address the recent policy innovations and their implications for potential reform.
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Daniel Eduardo Chavez and Haipeng (Allan) Chen
The purpose of this paper is to propose an overarching unifying theory where first-mover advantages are a conditional effect, not a main effect. By offering a closer look at how…
Abstract
Purpose
The purpose of this paper is to propose an overarching unifying theory where first-mover advantages are a conditional effect, not a main effect. By offering a closer look at how the firm, market and product characteristics influence the supply and demand of innovations, this research furthers our understanding of the advantages and disadvantages for first movers.
Design/methodology/approach
This paper explores first-mover advantages as a conditional effect. Adopting a contingency perspective, the authors review the literature in marketing, strategic management, innovation and entrepreneurship to offer a conceptual framework putting innovation success at the core of first-mover advantages. The authors develop an inventory of propositions specifying how first-mover advantages depend on various firm features, market characteristics and product properties through their effects on the success of innovations.
Findings
A conceptual framework centered around innovation success yields testable hypotheses that are coherent with extant research on first-mover advantages and reconcile the seemingly contradictory evidence in that body of work.
Practical implications
This research provides managers with the opportunity to think about one of the most important decisions, i.e. time of entry, not as a linear finite decision, but instead as a flow with the innovations and potential for their success in mind.
Originality/value
This paper distinguishes itself from the existing literature with its focus on innovation within a contingency perspective for first-mover advantages.
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Jing Zheng, Chuan‐You Deng, Shao‐Min Cheng, Wen‐Ya Liu and A‐Tao Wang
The purpose of this paper is to examine the great contributions made by the American library expert, Mary Elizabeth Wood, to Chinese library development.
Abstract
Purpose
The purpose of this paper is to examine the great contributions made by the American library expert, Mary Elizabeth Wood, to Chinese library development.
Design/methodology/approach
As a pioneer of the modern library movement Mary Elizabeth Wood devoted herself to a Chinese library career. It was structured according to the following theme: setting up the Boone Library and introducing the modern American public library into China; establishing Boone Library School and initiating Chinese library science education; raising money and appealing for China's library development; helping forward the foundation of the Library Association of China; as well as promoting Chinese library intercommunion and cooperation with the West.
Findings
With the background of underdeveloped Chinese librarianship, Mary Elizabeth Wood introduced modern American public library spirit into China, opened the gate of Chinese library science, and promoted Chinese library science.
Research limitations/implications
The paper discusses the library history of China and the role of an American librarian in Chinese library history; thus, it should be of wide interest to researchers involved in library history.
Originality/value
Mary Elizabeth Wood devoted herself to a Chinese library career, and promoted Chinese library science greatly, but research on her is limited. This paper considers her contribution to Chinese library science.
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Michele Ciotti, Giampaolo Campana and Mattia Mele
This paper aims to present a survey concerning the accuracy of thermoplastic polymeric parts fabricated by additive manufacturing (AM). Based on the scientific literature, the aim…
Abstract
Purpose
This paper aims to present a survey concerning the accuracy of thermoplastic polymeric parts fabricated by additive manufacturing (AM). Based on the scientific literature, the aim is to provide an updated map of trends and gaps in this relevant research field. Several technologies and investigation methods are examined, thus giving an overview and analysis of the growing body of research.
Design/methodology/approach
Permutations of keywords, which concern materials, technologies and the accuracy of thermoplastic polymeric parts fabricated by AM, are used for a systematic search in peer-review databases. The selected articles are screened and ranked to identify those that are more relevant. A bibliometric analysis is performed based on investigated materials and applied technologies of published papers. Finally, each paper is categorised and discussed by considering the implemented research methods.
Findings
The interest in the accuracy of additively manufactured thermoplastics is increasing. The principal sources of inaccuracies are those shrinkages occurring during part solidification. The analysis of the research methods shows a predominance of empirical approaches. Due to the experimental context, those achievements have consequently limited applicability. Analytical and numerical models, which generally require huge computational costs when applied to complex products, are also numerous and are investigated in detail. Several articles deal with artificial intelligence tools and are gaining more and more attention.
Originality/value
The cross-technology survey on the accuracy issue highlights the common critical aspects of thermoplastics transformed by AM. An updated map of the recent research literature is achieved. The analysis shows the advantages and limitations of different research methods in this field, providing an overview of research trends and gaps.