Zhiwei Li, Wenxin Huai, Zhonghua Yang, Zhongdong Qian and Yuhong Zeng
A radial offset jet has the flow characteristics of a radial jet and an offset jet, which are encountered in many engineering applications. The purpose of this paper is to study…
Abstract
Purpose
A radial offset jet has the flow characteristics of a radial jet and an offset jet, which are encountered in many engineering applications. The purpose of this paper is to study the dynamics and mass transfer characteristics of the radial offset jet with an offset ratio 6, 8 and 12.
Design/methodology/approach
Three turbulence models, namely the SST k-? model, detached eddy simulation model, and improved delayed detached eddy simulation (IDDES), were applied to the radial offset jet with an offset ratio eight and their results were compared with experimental results. The contrasting results, such as the distributions of mean and turbulent velocity and pressure, show that the IDDES model was the best model in simulating the radial offset jet. The results of the IDDES were analyzed, including the Reynolds stress, turbulent kinetic energy, triple-velocity correlations, vertical structure and the tracer concentration distribution.
Findings
In the axisymmetric plane, Reynolds stresses increase to reach a maximum at the location where the jet central line starts to be bent rapidly, and then decrease with increasing distance in the radial direction. The shear layer vortices, which arise from the Kelvin-Helmholtz instability near the jet exit, become larger scale results in the entrainment and vortex pairing, and breakdown when the jet approaches the wall. Near the wall, the vortex swirling direction is different at both front and back of attachment point. In the wall-jet region, the concentration distributions present self-similarity while it keeps constant below the jet in the recirculation region.
Research limitations/implications
The radial offset jet with other offset ratio and exit angle is not considered in this paper and should be investigated.
Originality/value
The results obtained in this paper will provide guidance for studying similar flow and a better understanding of the radial offset jet.
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Wanyun Xue, Wenxin Huai, Zhongdong Qian, Zhonghua Yang and Yuhong Zeng
The purpose of this paper is to examine the initial mixing of wastewater discharged from submerged outfall diffusers and the influence of port configurations on wastewater…
Abstract
Purpose
The purpose of this paper is to examine the initial mixing of wastewater discharged from submerged outfall diffusers and the influence of port configurations on wastewater distribution based on computational results.
Design/methodology/approach
Marine wastewater discharges from multiport diffusers are investigated by numerically solving three-dimensional and uncompressible two-phase flow fields. A mixture model simulates this flow and the standard k-e model to resolve flow turbulence; inter-phase interactions were described in terms of relative slip velocity between phases. Computations were performed for two values of the port spacings s/H with different current Froude numbers F.
Findings
Computational results compared well with previous laboratory measurements. Numerical results reveal that for both the closely spaced (s/H=0.21) and widely spaced (s/H=3.0) ports, the normalized dilution Sn becomes independent of F; further, the length of the near field xn and the spreading layer thickness hn are functions of F. For the closely spaced ports, the wastewater discharge behaves like a line plume, the Coanda effect is obvious, quasi-bifurcation is present, horseshoe structures of the jets in the planes are rapidly produced and then squashed and elongated, and the jet trajectories based on maximum velocity precede those based on maximum concentration. For the widely spaced ports, the wastewater discharge behaves like a point plume, the Coanda effect is not obvious, bifurcation is present, horseshoe structures of the jets in the planes are gradually produced and become ellipses, and the jet trajectories based on maximum velocity are similar to those based on maximum concentration.
Originality/value
Semi-empirical equations are presented to predict major near field characteristics. These provide guidance for designing multiport diffusers and assessing environmental impact.
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Chen Zhao, Zhonghua Gao, Yonghong Liu and Ou Yang
The authors propose a new motivation construct, political self-efficacy, and investigate how and when leader political mentoring influences follower political behavior and…
Abstract
Purpose
The authors propose a new motivation construct, political self-efficacy, and investigate how and when leader political mentoring influences follower political behavior and promotability through political self-efficacy.
Design/methodology/approach
The authors collected four samples to develop a scale for political self-efficacy and conducted two field studies of leader-follower dyads to examine the model.
Findings
Leader political mentoring enhances followers' political behavior and promotability through increasing their political self-efficacy. These positive indirect effects are stronger when followers have a higher positive political perception.
Originality/value
This study integrates mentoring research with organizational politics literature and theorizes how a domain-specific self-efficacy—political self-efficacy, translates the positive impact of leader political mentoring on constructive behavioral and career-related outcomes.
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Xinmin Dai, Amy H. Lau and Ji‐liang Yang
Explains why, following China‘s implementation of a market economy, public accounting firms were required to affiliate (hook‐up) with existing government or educational…
Abstract
Explains why, following China‘s implementation of a market economy, public accounting firms were required to affiliate (hook‐up) with existing government or educational institutions until 1993 when partnerships and limited liability firms were also allowed. Describes the rules relating to independent accounting firms and changes which should foster their development but reports that, in fact, most firms are still affiliated. Discusses the reasons for this and the resulting problems, e.g. lack of competition and independence, low quality of service and increases in fraud, misrepresentation and under‐disclosure. Reveals that despite the 1995 exposure draft on eliminating the hooking‐up structure few de‐affiliations have taken place and identifies four problems which need solving if full de‐affiliation is to be achieved.
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Feng Li, Zhonghua Yu and Zhensheng Yang
This paper aims to focus on investigating the failure mode of fused deposition modeling (FDM) fabricated parts by using acoustic emission (AE) technique.
Abstract
Purpose
This paper aims to focus on investigating the failure mode of fused deposition modeling (FDM) fabricated parts by using acoustic emission (AE) technique.
Design/methodology/approach
Considering the special prototyping way of FDM, the failure modes of FDM-fabricated parts were investigated experimentally. One test was carried out and the other two describe what has been observed on this basis. Acoustic emissions are obtained during the tensile process. AE features of peak frequency, energy and amplitude are extracted and preliminarily analyzed. Then, the unsupervised clustering method of k-means is applied to explore the relationship between the failure modes and the AE signals.
Findings
Failure modes of filament debonding and breakage can be successfully recognized by the pattern recognition technique of k-means.
Practical implications
The results obtained can help us understand the failure process of FDM printed parts. This will provide an available monitoring method in the application of FDM-fabricated parts.
Originality/value
This paper has investigated and characterized the failure modes of FDM fabricated parts for the first time.
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Xiufeng Cheng, Ziming Zhang, Yue Yang and Zhonghua Yan
Social coding platforms (SCPs) have been adopted by scores of developers in building, testing and managing their codes collaboratively. Accordingly, this type of platform (site…
Abstract
Purpose
Social coding platforms (SCPs) have been adopted by scores of developers in building, testing and managing their codes collaboratively. Accordingly, this type of platform (site) enables collaboration between enterprises and universities (c-EU) at a lower cost in the form of online team-building projects (repositories). This paper investigates the open collaboration patterns between these two parties on GitHub by measuring their online behaviours. The purpose of this investigation is to identify the most attractive collaboration features that enterprises can offer to increase university students' participation intentions.
Design/methodology/approach
The research process is divided into four steps. First, the authors crawled for numerical data for each interactive repository feature created by employees of Alibaba on GitHub and identified the student accounts associated with these repositories. Second, a categorisation schema of feature classification was proposed on a behavioural basis. Third, the authors clustered the aforementioned repositories based on feature data and recognised four types of repositories (popular, formal, normal and obsolete) to represent four open collaboration patterns. The effects of the four repository types on university students' collaboration behaviour were measured using a multiple linear regression model. An ANOVA test was implemented to examine the robustness of research results. Finally, the authors proposed some practical suggestions to enhance collaboration between both sides of SCPs.
Findings
Several counterintuitive but reasonable findings were revealed, for example, those based on the “star” repository feature. The actual coding contribution of the repositories had a negative correlation with student attention. This result indicates that students were inclined to imitate rather than innovate.
Originality/value
This research explores the open collaboration patterns between enterprises and universities on GitHub and their impact on student coding behaviour. According to the research analysis, both parties benefit from open collaboration on SCPs, and the allocation or customisation of online repository features may affect students' participation in coding. This research brings a new perspective to the measurement of users' collaboration behaviour with output rates on SCPs.
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Paolo Dello Vicario and Valentina Tortolini
The purpose of this paper is to define a methodology to analyze links between programming topics and libraries starting from GitHub data.
Abstract
Purpose
The purpose of this paper is to define a methodology to analyze links between programming topics and libraries starting from GitHub data.
Design/methodology/approach
This paper developed an analysis over machine learning repositories on GitHub, finding communities of repositories and studying the anatomy of collaboration around a popular topic such as machine learning.
Findings
This analysis indicates the significant importance of programming languages and technologies such as Python and Jupyter Notebook. It also shows the rise of deep learning and of specific libraries such as Tensorflow from Google.
Originality/value
There exists no survey or analysis based on how developers influence each other for specific topics. Other researchers focused their analysis on the collaborative structure and social impact instead of topic impact. Using this methodology to analyze programming topics is important not just for machine learning but also for other topics.
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Bo Song and Zhonghua Zhao
How do institutional pressures influence the cluster firm’s innovation? Institutional pressure consists of regulative, normative and cognitive pressures; most scholars have only…
Abstract
Purpose
How do institutional pressures influence the cluster firm’s innovation? Institutional pressure consists of regulative, normative and cognitive pressures; most scholars have only focused on the influence of regulative pressure as institutional environment on innovation. In addition, the nature of strategic cognition, as the mediator act on innovation strategy, remains underexplored in the literature. Based on institution theory and ambidextrous innovation theory, this study aims to propose a framework to examine the mechanism of institutional pressures acting on ambidextrous innovation through the moderated mediating role of strategic cognition in clusters.
Design/methodology/approach
Using survey data collected from 422 sampled firms in China, regression models were used to test hypotheses from the mediating role of strategic cognition between institutional pressures and cluster firm’s ambidextrous innovation.
Findings
The results showed that regulative, cognitive pressures and, especially, normative pressures have significant positive effects on cluster firms’ ambidextrous innovation. Strategic cognition presented by prospector and analyzer mediates the relationship between institutional pressure and ambidextrous innovation except defender; dynamic environment positively moderates the mediating effects of prospector cognition on explorative innovation, and negatively moderates the mediating effects of analyzer cognition on exploitative innovation.
Originality/value
The findings of this study have some implications that strategic cognition played a partially meditating role between the institutional pressure and ambidextrous innovation. Government should construct a dynamic innovation policy system according to the resource endowment in different regions; furthermore, classification support system to cluster firms with different strategic cognition should be built.
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Jinglong Liu, Zhonghua Wu, Xiaowen Xing and Qizhi He
The purpose of this paper is to find an omnidirectional robust gust response stabilization (GRS) scheme with anti-disturbance and state-limited features.
Abstract
Purpose
The purpose of this paper is to find an omnidirectional robust gust response stabilization (GRS) scheme with anti-disturbance and state-limited features.
Design/methodology/approach
Disturbance observer and barrier Lyapunov techniques, which can, respectively, estimate the lumped disturbances of the dynamic system in real-time and ensure the middle states within some prescribed ranges according to some flight safety indexes.
Findings
In the existing literature, almost all of the GRS controllers are either only for the longitudinal dynamics or only for the latitudinal dynamics. Few studies have considered the gust response alleviation problem with omnidirectional wind disturbance and full aircraft model.
Originality/value
This paper proposes a fresh scheme to deal with a more holistic GRS problem; the disturbance observer based (DOB) barrier Lyapunov backstepping longitudinal controller has been put forward; DOB nonlinear dynamic inversion to handle the multi-input-multi-output lateral dynamics; and to closely connect the two loops of the latitudinal dynamics, a manipulating variable conversion method is proposed.
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Abstract
Purpose
This paper traces the incorporation of western educational histories in the development of normal-school curricula during the late Qing Dynasty and the Republic of China (1901–1944). It uses publication networks to show how the study of comparative educational history facilitated the international circulation of knowledge in the teaching profession, and how the “uses” of educational history were shaped by larger geopolitical forces.
Design/methodology/approach
This paper analyzes the international exchange of texts between normal schools in China and Japan and, subsequently, between normal schools in China and the United States. A database of 107 publications in the field of western educational history that were adopted in China reveals specific patterns of textual citation, cross-reference, and canon-formation in the field of educational historiography.
Findings
With conclusions derived from a combination of social network analysis and clustering analysis, this paper identifies three broad stages in China's development of normal-school curricula in comparative educational history: “Japan as Teacher,” “transitional period” and “America as Teacher.”
Research limitations/implications
Statistical analysis can reveal citation and reference patterns but not readers' understanding of the deeper meaning of texts – in this case, textbooks on the subject of western educational history. In addition, the types of publications analyzed in this study are relatively limited, the articles on the history of education in journals have not become the main objects of this study.
Originality/value
This paper uses both quantitative and qualitative methods to uncover the transnational circulation of knowledge in the field of comparative educational history during its formative period in China.