Wenqiang Guo, Guoxiang Hou, Yin Guan and Senyun Liu
This paper aims to explore the mechanism of the slip phenomenon at macro/micro scales, and analyze the effect of slip on fluid flow and heat transfer, to reduce drag and enhance…
Abstract
Purpose
This paper aims to explore the mechanism of the slip phenomenon at macro/micro scales, and analyze the effect of slip on fluid flow and heat transfer, to reduce drag and enhance heat transfer.
Design/methodology/approach
The improved tangential momentum accommodation coefficient scheme incorporated with Navier’s slip model is introduced to the discrete unified gas kinetic scheme as a slip boundary condition. Numerical tests are simulated using the D2Q9 model with a code written in C++.
Findings
Velocity contour with slip at high Re is similar to that without slip at low Re. For flow around a square cylinder, the drag is reduced effectively and the vortex shedding frequency is reduced. For flow around a delta wing, drag is reduced and lift is increased significantly. For Cu/water nanofluid in a channel with surface mounted blocks, drag can be reduced greatly by slip and the highest value of drag reduction (DR) (67.63%) can be obtained. The highest value of the increase in averaged Nu (11.78%) is obtained by slip at Re = 40 with volume fraction φ=0.01, which shows that super-hydrophobic surface can enhance heat transfer by slip.
Originality/value
The present study introduces and proposes an effective and superior method for the numerical simulation of fluid/nanofluid slip flow, which has active guidance meaning and applied value to the engineering practice of DR, heat transfer, flow control and performance improvement.
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Zhifang Wang, Jianguo Yu, Shangjing Lin, Junguo Dong and Zheng Yu
The paper takes the air-ground integrated wireless ad hoc network-integrated system as the research object, this paper aims to propose a distributed robust H∞ adaptive…
Abstract
Purpose
The paper takes the air-ground integrated wireless ad hoc network-integrated system as the research object, this paper aims to propose a distributed robust H∞ adaptive fault-tolerant control algorithm suitable for the system to distribute to solve the problem of control and communication failure at the same time.
Design/methodology/approach
In the paper, the authors propose a distributed robust H∞ adaptive fault-tolerant control algorithm suitable for the air-ground integrated wireless ad hoc network-integrated system.
Findings
The results show that the integrated system has good robustness and fault tolerance performance indicators for flight control and wireless signal transmission when confronted with external disturbances, internal actuator failures and wireless network associated failures and the flight control curve of the quadrotor unmanned aerial vehicle (UAV) is generally smooth and stable, even if it encounters external disturbances and actuator failures, its fault tolerance performance is very good. Then in the range of 400–800 m wireless communication distance, the success rate of wireless signal loop transmission is stable at 80%–100% and the performance is at least relatively improved by 158.823%.
Originality/value
This paper takes the air-ground integrated wireless ad hoc network-integrated system as the research object, based on the robust fault-tolerant control algorithm, the authors propose a distributed robust H∞ adaptive fault-tolerant control algorithm suitable for the system and through the Riccati equation and linear matrix inequation method, the designed distributed robust H∞ adaptive fault-tolerant controller further optimizes the fault suppression factor γ, so as to break through the limitation of only one Lyapunov matrix for different fault modes to distribute to solve the problem of control and communication failure at the same time.
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Hui Zhang, David Bourell, Yanling Guo, Xiaodong Zhang, Yu Zhuang, Yueqiang Yu, Kaiyi Jiang and Wasim M.K. Helal
A pine/co-PES composite (PCPES composite) was proposed as the feedstock for powder bed fusion (laser sintering, LS). This paper aims to provide some necessary experimental data…
Abstract
Purpose
A pine/co-PES composite (PCPES composite) was proposed as the feedstock for powder bed fusion (laser sintering, LS). This paper aims to provide some necessary experimental data and the theoretical foundation for LS of pine/co-PES, especially for the application of using the laser-sintered pine/co-PES parts as complex structural patterns in investment casting.
Design/methodology/approach
The PCPES composites with different pine loadings were mixed mechanically. The composite’s preheating temperature and processing temperature during LS were determined experimentally based on the material’s thermal behavior. The effects of pine powder on the binding mechanism of PCPES composites were discussed through analyzing the microstructure of the laser-sintered parts’. Mechanical properties and dimensional precision of laser-sintered PCPES parts in different pine loadings were tested, and the parts’ mechanical properties were strengthened by wax-infiltration post-processing. The influence extents of process parameters on the mechanical properties of laser-sintered 20 Wt.% pine/co-PES parts were investigated using a 1/2 fractional factorials experiment.
Findings
20 Wt.% pine/co-PES is considered to be a promising wood-plastic composite for laser sintering. The relationship between mechanical strength of its laser-sintered parts and process parameters was built up using mathematical formulas. Experimental results show density, tensile strength, flexural strength and surface roughness of laser-sintered 20 Wt.% pine/co-PES parts are improved by 72.7-75.0%, 21.9-111.3%, 26.8-86.2%, 27.0-29.1% after post-process infiltration with a wax. A promising application of the wax-infiltrated laser-sintered parts is for investment casting cores and patterns.
Research limitations/implications
The proper process parameters and forming properties of laser-sintered parts are limited to the results of laser sintering experiments carried on using AFS 360 rapid prototyping device.
Originality/value
This investigation not only provides a new feedstock for laser sintering with the advantages of low cost and fabricability but also uses an advanced technique to produce personalized wood-plastic parts efficiently. Mathematical models between mechanical properties of laser-sintered PCPES parts and LS process parameters will guide the further LS experiments using the 20 Wt.% pine/co-PES composite. Besides, the laser-sintered PCPES parts after wax-infiltration post-processing are promising as complex structural patterns for use in investment casting.
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Vasilii Erokhin and Tianming Gao
Sustainable development is inseparable from rational and responsible use of resources and promotion of green entrepreneurship. The contemporary green development agenda…
Abstract
Sustainable development is inseparable from rational and responsible use of resources and promotion of green entrepreneurship. The contemporary green development agenda encompasses climate, economic, technical, social, cultural, and political dimensions. International efforts to greening the global development are conducted by the major economies, including China as the world’s largest consumer of energy and the biggest emitter of greenhouse gases. China is aware of its environmental problems, as well as of its part of the overall responsibility for the accomplishment of the sustainable development goals. By means of the decarbonization efforts, the latter are integrated both into the national development agenda (the concept of ecological civilization) and China’s international initiatives (the greening narrative within the Belt and Road Initiative). Over the past decade, China has made a breakthrough on the way to promoting green entrepreneurship and greening of its development (better quality of air and water, renewable energy, electric vehicles, and organic farming). On the other hand, emissions remain high, agricultural land loses productivity, and freshwater resources degrade due to climate change. In conventional industries (oil, coal mining, and electric and thermal energy), decarbonization faces an array of impediments. In this chapter, the authors summarize fundamental provisions of China’s approach to building an ecological civilization and measures to reduce emissions and achieve the carbon neutrality status within the nearest decades. The analysis of obstacles to the decarbonization of the economy and possible prospects for the development of green entrepreneurship summarizes China’s practices for possible use in other countries.
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Mayank Shrivastava, Anthony Abu, Rajesh Dhakal and Peter Moss
This paper aims to describe current trends in probabilistic structural fire engineering and provides a comprehensive summary of the state-of-the-art of performance-based…
Abstract
Purpose
This paper aims to describe current trends in probabilistic structural fire engineering and provides a comprehensive summary of the state-of-the-art of performance-based structural fire engineering (PSFE).
Design/methodology/approach
PSFE has been introduced to overcome the limitations of current conventional design approaches used for the design of fire-exposed structures, which investigate assumed worst-case fire scenarios and include multiple thermal and structural analyses. PSFE permits buildings to be designed in relation to a level of life safety or economic loss that may occur in future fire events with the help of a probabilistic approach.
Findings
This paper brings together existing research on various sources of uncertainty in probabilistic structural fire engineering, such as elements affecting post-flashover fire development, material properties, fire models, fire severity, analysis methods and structural reliability.
Originality/value
Prediction of economic loss would depend on the extent of damage, which is further dependent on the structural response. The representative prediction of structural behaviour would depend on the precise quantification of the fire hazard. The incorporation of major uncertainty sources in probabilistic structural fire engineering is explained, and the detailed description of a pioneering analysis method called incremental fire analysis is presented.
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Libiao Bai, Shiyi Liu, Yuqin An and Qi Xie
Project portfolio benefit (PPB) evaluation is crucial for project portfolio management decisions. However, PPB is complex in composition and affected by synergy and ambidexterity…
Abstract
Purpose
Project portfolio benefit (PPB) evaluation is crucial for project portfolio management decisions. However, PPB is complex in composition and affected by synergy and ambidexterity. Ignoring these characteristics can result in inaccurate assessments, impeding the management and optimization of benefit. Considering the above complexity of PPB evaluation, this study aims to propose a refined PPB evaluation model to provide decision support for organizations.
Design/methodology/approach
A back propagation neural network optimized via genetic algorithm and pruning algorithm (P-GA-BPNN) is constructed for PPB evaluation. First, the benefit evaluation criteria are established. Second, the inputs and expected outputs for model training and testing are determined. Then, based on the optimization of BPNN via genetic algorithm and pruning algorithm, a PPB evaluation model is constructed considering the impacts of ambidexterity and synergy on PPB. Finally, a numerical example was applied to validate the model.
Findings
The results indicate that the proposed model can be used for effective PPB evaluation. Moreover, it shows superiority in terms of MSE and fitting effect through extensive comparative experiments with BPNN, GA-BPNN, and SVM models. The robustness of the model is also demonstrated via data random disturbance experiment and 10-cross-validation. Therefore, the proposed model could serve as a valuable decision-making tool for PPB management.
Originality/value
This study extends prior research by integrating the impacts of synergy and ambidexterity on PPB when conducting PPB evaluation, which facilitates to manage and enhance PPB. Besides, the structural redundancy of existing assessment methods is solved through the dynamic optimization of the network structure via the pruning algorithm, enhancing the effectiveness of PPB decision-making tools.
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Limin Guo, Jinlian Luo and Ken Cheng
Integrating appraisal theories of discrete emotions with the emotion regulation literature, this study aims to explore the relationships between exploitative leadership and…
Abstract
Purpose
Integrating appraisal theories of discrete emotions with the emotion regulation literature, this study aims to explore the relationships between exploitative leadership and certain types of counterproductive workplace behavior (CWB). Besides, this study seeks to examine the mediating roles of discrete emotions (i.e. anger and fear) and the moderating role of cognitive reappraisal within the proposed relationships.
Design/methodology/approach
Based on time-lagged survey data from 440 Chinese employees, this study conducted hierarchical regression analysis and bootstrapping approach to test the hypotheses.
Findings
The results revealed that exploitative leadership was positively related to approach-oriented CWB and avoidance-oriented CWB. In addition, this study found that anger mediated the relationship between exploitative leadership and approach-oriented CWB, whereas fear mediated the relationship between exploitative leadership and avoidance-oriented CWB. Further, cognitive reappraisal buffered the positive effects of exploitative leadership on anger and fear and the indirect effects of exploitative leadership on approach-oriented CWB (via anger) and avoidance-oriented CWB (via fear).
Practical implications
Managers should reduce leaders' exploitation and enhance employees' skills on emotional management and cognitive reappraisal.
Originality/value
First, by verifying the effects of exploitative leadership on both approach-oriented and avoidance-oriented CWB, this study adds to the literature on exploitive leadership and provides a more complete understating of the relationship between exploitative leadership and workplace deviance. Second, this study enriches the understanding of the process through which exploitative leadership affects employees by demonstrating the novel mediating roles of discrete emotions (i.e. anger and fear) through the lens of appraisal theories of discrete emotions. Third, by verifying the moderating role of cognitive reappraisal, this study provides insights into the boundary conditions of the influences of exploitive leadership.
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Yongqiang Sun, Yafei Feng, Xiao-Liang Shen and Xitong Guo
Prior researches on the adoption of mobile health services (MHS) concentrate on the subjective cognitive appraisals resulting in technology adoption, while ignoring how to shape…
Abstract
Purpose
Prior researches on the adoption of mobile health services (MHS) concentrate on the subjective cognitive appraisals resulting in technology adoption, while ignoring how to shape those cognitive appraisals by the objective message design strategies which are easier to operate in practice. Based on protection motivation theory (PMT), the current research aims to explore the antecedents of cognitive appraisals by focusing on message design strategies of fear appeal and coping appeal.
Design/methodology/approach
A two-stage scenario-based survey of 204 participants was conducted to collect data. The authors chose SPSS and covariance-based structural equation modeling (CB-SEM) approach with the software LISREL 8.8 to test our model.
Findings
The results show that the relationship between fear appeal and fear arousal is inverted U-shaped such that the degree of fear arousal is the greatest when the fear appeal is at a moderate level. Perceived usefulness for the message with negative framing is higher than that with positive framing. Furthermore, fear appeal and coping appeal have a significant interaction on the adoption of MHS at different stages.
Research limitations/implications
The sample data of this study come from a special health service of a special group in China, which limits the universality of our research results for other groups or health care services. Therefore, future researchers can validate the model in other research scenarios and sample populations.
Originality/value
This study shows how fear appeal and coping appeal work together to influence individuals' adoption intention. The authors’ findings expand the theoretical depth of PMT and fear theory, enriching the theoretical connotation of framing effect in mobile health technology adoption context, which add new insights to design more persuasive messages through fear appeal and coping appeal for researchers and MHS providers in mobile health communication or propaganda.
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Xing Zhang, Shan Liu, Li Wang, Yajun Zhang and Jiayin Wang
Mobile health service (MHS) can provide users with convenient health services and information to reduce their medical costs from aging or other health issues. Previous studies…
Abstract
Purpose
Mobile health service (MHS) can provide users with convenient health services and information to reduce their medical costs from aging or other health issues. Previous studies confirm the underdevelopment of the Chinese MHS. The purpose of this paper is to analyze the factors that affect the intention to use MHS.
Design/methodology/approach
This paper develops a research model that integrates personal health differences with theory of planned behavior (TPB) and protection motivation theory (PMT). This model is empirically tested using data from 494 valid questionnaires. Structural equation modeling is used to test the hypotheses.
Findings
Perceived vulnerability to disease, perceived severity of disease, response efficacy and self-efficacy positively affect attitude, thereby exerting a positive influence on the behavioral intention to use MHS. Subjective norms also influence users’ behavioral intention. Personal health status and personal health value have quasi-moderating effects on the relationship between attitude and behavioral intention.
Originality/value
This paper presents an early attempt to conceptualize and validate a research model of MHS acceptance by integrating TPB and PMT in a complementary manner. The integrated model provides a holistic view of people’s intention to use MHS by considering health threat beliefs, individual role (i.e. attitude and self-efficacy) and social influences (i.e. subjective norms). Furthermore, this research highlights the role of two individual health characteristics (i.e. personal health status and personal health value) in MHS adoption. These new findings are beneficial toward an in-depth understanding of technology adoption in the MHS context.
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Changyu Wang, Yimeng Zhang and Jiaojiao Feng
Exploitative leadership as a form of destructive leadership may hinder employees' knowledge sharing. However, how and when exploitative leadership impacts employees' knowledge…
Abstract
Purpose
Exploitative leadership as a form of destructive leadership may hinder employees' knowledge sharing. However, how and when exploitative leadership impacts employees' knowledge sharing is under explored. Drawing on fairness heuristic theory, this study aims to construct a moderated mediation model to investigate the impacting mechanisms of exploitative leadership on employees' knowledge sharing by introducing organization-based self-esteem as a mediator and perceived organizational procedural justice as a moderator.
Design/methodology/approach
To test the research model, data were collected from 148 full-time employees at two-time points and analyzed using partial least square-structural equation modelling (PLS-SEM).
Findings
Exploitative leadership has a direct negative impact on knowledge sharing. Through the mediation of organization-based self-esteem, exploitative leadership has an indirect impact on knowledge sharing. Organizational procedural justice can weaken the indirect negative relationship between exploitative leadership and knowledge sharing via organization-based self-esteem.
Originality/value
This study is the first to introduce fairness heuristic theory to explain the relationship between exploitative leadership and knowledge sharing. Findings about the mediating role of organizational self-esteem and the moderating role of organizational procedural justice in the relationship between exploitative leadership and knowledge sharing can uncover the black box of how exploitative leadership affects knowledge sharing.