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Article
Publication date: 16 June 2022

Yaquan Han, Jihe Wang, Haifeng Huang, Jun Sun and Yue Sun

This study aims to establish the laser links between satellites among large-scale distributed satellite systems; a combined attitude control strategy containing two stages…

Abstract

Purpose

This study aims to establish the laser links between satellites among large-scale distributed satellite systems; a combined attitude control strategy containing two stages is proposed in this paper.

Design/methodology/approach

These two stages are: one is the attitude initial pointing control to change the attitude of satellite pointing to the other satellite based on the position information of each satellite; the other one is the high precision attitude tracking control to scan the uncertainty cone because the initial pointing control accuracy is not enough to establish the laser link. At the initial pointing control stage, a method to determine the target attitude of each satellite is presented based on the position information of each satellite, and the fuzzy adaptive control algorithm is used to control the satellites to its calculated attitude. Then, at the high precision attitude tracking control stage, a strategy for laser link acquisition and scanning the uncertainty cone by the lasers of the spacecraft is proposed, and an angular velocity tracking scanning controller is designed while the convergence of the attitude tracking error is ensured through Lyapunov–Krasovskii theory.

Findings

Simulations are conducted to verify the effectiveness of the proposed control algorithm, and the laser link for a large-scale distributed satellite system with super long distance is achieved through a combined attitude control strategy.

Research limitations/implications

A combined attitude control strategy is valid for a large-scale distributed satellite system with super long distance.

Practical implications

A combined attitude control strategy can be used to achieve laser link acquisition for a large-scale distributed satellite system like space gravitational wave detection.

Originality/value

A combined attitude control strategy can provide a way to solve the typical problem that pointing control accuracy is not enough to establish the laser link for a large-scale distributed satellite system.

Details

Aircraft Engineering and Aerospace Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 9 August 2022

Hanieh Javadi Khasraghi, Xuan Wang, Jun Sun and Bahar Javadi Khasraghi

To obtain optimal deliverables, more and more crowdsourcing platforms allow contest teams to submit tentative solutions and update scores/rankings on public leaderboards…

Abstract

Purpose

To obtain optimal deliverables, more and more crowdsourcing platforms allow contest teams to submit tentative solutions and update scores/rankings on public leaderboards. Such feedback-seeking behavior for progress benchmarking pertains to the team representation activity of boundary spanning. The literature on virtual team performance primarily focuses on team characteristics, among which network closure is generally considered a positive factor. This study further examines how boundary spanning helps mitigate the negative impact of network closure.

Design/methodology/approach

This study collected data of 9,793 teams in 246 contests from Kaggle.com. Negative binomial regression modeling and linear regression modeling are employed to investigate the relationships among network closure, boundary spanning and team performance in crowdsourcing contests.

Findings

Whereas network closure turns out to be a negative asset for virtual teams to seek platform feedback, boundary spanning mitigates its impact on team performance. On top of such a partial mediation, boundary spanning experience and previous contest performance serve as potential moderators.

Practical implications

The findings offer helpful implications for researchers and practitioners on how to break network closure and encourage boundary spanning with the establishment of facilitating structures in crowdsourcing contests.

Originality/value

The study advances the understanding of theoretical relationships among network closure, boundary spanning and team performance in crowdsourcing contests.

Details

Information Technology & People, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0959-3845

Keywords

Article
Publication date: 15 May 2017

Yanyan Gao, Jun Sun and Qin Zhou

The purpose of this paper is to estimate the effectiveness of the credit evaluation system using the borrowing data from China’s leading P2P lending platform, Renrendai.com.

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Abstract

Purpose

The purpose of this paper is to estimate the effectiveness of the credit evaluation system using the borrowing data from China’s leading P2P lending platform, Renrendai.com.

Design/methodology/approach

The current credit valuation systems are classified into the forward-looking mechanism, which judges the borrowers’ credit levels based on their uploaded information, and the backward-looking mechanism, which judges the borrowers’ credit levels based on their historical repayment performance. Probit models and Tobit models are used to examine the effectiveness of credit evaluation mechanisms.

Findings

The results show that only the “hard” information reflecting borrowers’ credit ability can explain the default risk on the platform under the forward-looking credit evaluation mechanism. The backward-looking credit evaluation mechanism (BCEM) based on the repeated borrowings produces both promise-enhancing and “fishing” incentives and thus fails to explain the default risk, and weakens the effectiveness of forward-looking credit indicators in explaining the default risk because it encourages borrowers to invest in forging forward-looking credit indicators. Additional information such as the interest rate and the repayment periods reveals borrowers’ credit and thus can also be used as a predictor of borrowers’ default risk.

Practical implications

The findings suggest that current ex ante screening based on the information collected from the borrowers or repeated borrowings is inadequate to control the default risk in P2P lending markets and thus needs be improved. Ex post monitoring and sharing on defaulter’s information should be strengthened to increase the default cost and thus to deter potential bad borrowers.

Originality/value

To the authors’ knowledge, this is the first paper classifying the credit evaluation system in online P2P lending market into the forward-looking type and the backward-looking type, which is important since they provide different incentives to borrowers. The paper also investigates and provides evidence on the promise-enhancing and “fishing” incentives of BCEMs.

Details

China Finance Review International, vol. 7 no. 2
Type: Research Article
ISSN: 2044-1398

Keywords

Article
Publication date: 17 June 2022

Biao Li, Jun Sun, Hu Wang and Xiao Zhang

Under the action of many factors, the shaft of the shaft-journal bearing system inevitably moves along the axis direction at work, which will lead to the axial movement of…

Abstract

Purpose

Under the action of many factors, the shaft of the shaft-journal bearing system inevitably moves along the axis direction at work, which will lead to the axial movement of journal in the bearing. However, at present, only the dynamic and squeezing effects caused by the relative rotation and squeezing motion between the journal and the bearing surfaces are considered in the lubrication analysis of misaligned journal bearing and the axial movement of journal in the actual use of bearing is not considered. The purpose of this paper is to analyze the lubrication of journal bearing considering the axial movement of journal.

Design/methodology/approach

Taking the shaft-journal bearing system as the research object, a hydrodynamic lubrication model of journal bearing is established considering the axial movement and misalignment of journal. The finite difference method is used to solve the Reynolds equation for the lubrication analysis.

Findings

The axial movement of journal has a significant influence on the lubrication characteristics of misaligned journal bearing. The larger the misalignment angles of journal or the eccentricity of bearing, the greater the influence of the axial movement of journal on the lubrication performance of bearing. The lower the speed of bearing or the smaller the clearance of bearing, the more significant the influence of the axial movement of journal on the lubrication performance of bearing is.

Originality/value

The influence of the axial movement of journal on the lubrication performance of journal bearing is studied under different misalignment angles of journal, working conditions and clearances of bearing. The results of this paper are helpful to the design and research of the lubrication performance of journal bearing.

Details

Industrial Lubrication and Tribology, vol. 74 no. 7
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 29 April 2021

Jun Sun, Cynthia Changxin Wang, Zhiling Yang, Tianshu Yu, Jintao Li and Xiaoqian Xiong

Modern construction projects are increasingly complex and rely heavily on multi-discipline collaboration, and this leads to a more and more decentralized project-based…

Abstract

Purpose

Modern construction projects are increasingly complex and rely heavily on multi-discipline collaboration, and this leads to a more and more decentralized project-based structure widely adopted in the construction industry. While job satisfaction (JS) and job performance (JP) have been heavily studied previously, few considered the impact of organizational structure and none investigated the relationship between the organizational decentralization degree with JS and JP. This research aims to fill this research gap and investigate the impacts of organizational decentralization degree on JS and JP and facilitate a better project management practice for large-scale construction projects.

Design/methodology/approach

This research firstly establishes four hypotheses based on the literature review on general project-based organizations, then the hypotheses are tested by a survey covering 25 large complex construction projects in China. A hierarchical linear model analysis was carried out to analyze the survey data and to study the relationships between organizational decentralization degree, job satisfaction and job performance.

Findings

Analysis results show that projects' employees' JS and JP are positively correlated with the construction project organizations' decentralization degree, respectively. The decentralization degree has a higher impact on JS than on JP. Employees' JP is positively correlated with their JS, and a higher decentralization degree leads to a more significant positive impact that JS puts on JP.

Originality/value

The findings are new evidence of how construction organization structure and its decentralization degree can affect project employees' JS and JP. This research provides valuable guidance for the industry's management practice and is particularly important for large, complex and highly decentralized construction projects.

Details

Engineering, Construction and Architectural Management, vol. 29 no. 4
Type: Research Article
ISSN: 0969-9988

Keywords

Article
Publication date: 2 January 2018

Jun Sun, Xiande Wu, Shijie Zhang, Fengzhi Guo and Ting Song

The purpose of this paper is to propose an adaptive robust controller for coupled attitude and orbit control of rigid spacecraft based on dual quaternion in the presence…

Abstract

Purpose

The purpose of this paper is to propose an adaptive robust controller for coupled attitude and orbit control of rigid spacecraft based on dual quaternion in the presence of external disturbances and model uncertainties.

Design/methodology/approach

First, based on dual quaternion, a theoretical model of the relative motion for rigid spacecraft is introduced. Then, an adaptive robust controller which can realize coordinated control of attitude and orbit is designed in the existence of external disturbances and model uncertainties.

Findings

This paper takes advantage of the Lyapunov function which can guarantee the asymptotic stabilization of the whole system in the existence of parameters uncertainties. Simulation results show that the proposed controller is feasible and effective.

Originality/value

This paper proposes a coupled attitude and orbit adaptive robust controller based on dual quaternion. Simulation results demonstrate that the proposed controller can achieve higher control performance in the presence of parameters uncertainties.

Details

Aircraft Engineering and Aerospace Technology, vol. 90 no. 1
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 8 February 2022

Hua Du, Qi Han, Jun Sun and Cynthia Changxin Wang

This study aims to evaluate the effectiveness of different prefabricated construction (PC) policies using a case study in Wuhan, considering the local context.

Abstract

Purpose

This study aims to evaluate the effectiveness of different prefabricated construction (PC) policies using a case study in Wuhan, considering the local context.

Design/methodology/approach

The effectiveness of PC policies is falling behind expectations. The main reason lies in an insufficient understanding of the policy impacts. An agent-based model was built by choosing the residential sector in a typical large city of Wuhan, China, as the study case. Different cost reduction scenarios were introduced for investigating the PC policy effectiveness. The proposed model and simulation approach can be used for other cities and generalized to the whole Chinese PC industry with the potential to include more local policies and corresponding data.

Findings

Simulation results show that carbon emission reduction will be between 60,000 and 80,000 tons with policy incentives, nearly double that of the no policy intervention scenario. The target of 30% PC in all new buildings by 2026 in China is achievable with the subsidy policies of linear cost reduction, or cost reduction conforms to the learning curve.

Practical implications

Simulation results of three kinds of policy show that subsidy policy optimization is necessary regarding reducing the level of subsidy needed. The carbon credit policy is not essential since it has little influence on PC development. Implementing the project procurement restriction policy is not recommended if the scale of development of PC is more important than achieving the development target.

Originality/value

This study can help the government and developers make better policy and strategic decisions on PC development and boost the sustainability transition of the construction industry.

Details

Engineering, Construction and Architectural Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0969-9988

Keywords

Article
Publication date: 19 September 2019

Jun Sun, Xiao Zhang, Jianxiong Zhu, Yaming Gao, Hu Wang, Xiaoyong Zhao, Qin Teng, Yanping Ren and Guixiang Zhu

Currently, lubrication analysis of piston ring is generally done under engine rated operating condition. However, the engine (such as the vehicle engine) does not always…

Abstract

Purpose

Currently, lubrication analysis of piston ring is generally done under engine rated operating condition. However, the engine (such as the vehicle engine) does not always operate in rated operating condition, and its operating condition changes frequently in actual use. In addition, the lubrication status of piston ring is generally assumed as the flooded lubrication or a certain form of poor lubrication in most of the lubrication analysis.

Design/methodology/approach

In this paper, based on the equations about the flow rate of lubricating oil and the variation of control volume, the flow model of lubricating oil in the piston ring-cylinder liner conjunction is established. The lubrication analysis of piston ring for a four-stroke engine under different engine operating conditions is done, in which the lubricating oil at the inlet of piston ring is considered as the lubricating oil attached on the relevant location of cylinder wall after the piston ring moves over at the previous stroke.

Findings

There is remarkable difference for the lubrication characteristics of the piston ring under different engine operating conditions. The worst lubrication status of piston ring may not take place under engine rated operating condition.

Originality/value

In this paper, based on the measured engine cylinder pressure, the lubrication analysis of piston ring for a four-stroke engine under different engine operating conditions is done in which the lubricating oil supply condition at the inlet of piston ring is considered. The results of this paper are helpful for the design and research of engine piston ring-cylinder liner conjunction.

Details

Industrial Lubrication and Tribology, vol. 72 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 28 May 2021

Ying Yang, Mai Ha Pham, Biao Yang, Jun Wei Sun and Phuong Nguyen Thu Tran

While various aspects of the vegetable supply chain (SC) have been increasingly studied, most studies tend to investigate the downstream part of the SC in terms of…

Abstract

Purpose

While various aspects of the vegetable supply chain (SC) have been increasingly studied, most studies tend to investigate the downstream part of the SC in terms of customer demand and product quality. Relatively fewer studies have focused on upstream suppliers/farmers. This study aims to understand upstream farmers’ positions in different types of vegetable SCs and identify ways of enhancing sustainable vegetable SC collaboration.

Design/methodology/approach

This study is based on an in-depth case study of a cooperative SC in Vietnam from the perspectives of both the cooperative and its farmers.

Findings

The study found that cooperative SCs are the most appropriate for Vietnamese farmers. It also identified the key activities needed to engage farmers with cooperative SCs and the mechanisms that the cooperative needs to develop. Cooperative SCs can be enhanced only when farmers are motivated to engage in SC activities and when the cooperative implements a robust management mechanism.

Originality/value

This study provides new, insightful results on how to engage with small fragmented farmers for SC collaboration and how to enhance the roles of cooperative SCs in the vegetable industry in Vietnam. It also provides information for policymakers to support sustainable vegetable SC development and maintain its sustainability.

Details

Supply Chain Management: An International Journal, vol. 27 no. 1
Type: Research Article
ISSN: 1359-8546

Keywords

Article
Publication date: 8 February 2016

Jun Sun, Lei Shu, Xianhao Song, Guangsheng Liu, Feng Xu, Enming Miao, Zhihao Xu, Zheng Zhang and Junwei Zhao

This paper aims to use the crankshaft-bearing system of a four-cylinder internal combustion engine as the studying object, and develop a multi-objective optimization…

Abstract

Purpose

This paper aims to use the crankshaft-bearing system of a four-cylinder internal combustion engine as the studying object, and develop a multi-objective optimization design of the crankshaft-bearing. In the current optimization design of engine crankshaft-bearing, only the crankshaft-bearing was considered as the studying object. However, the corresponding relations of major structure dimensions exist between the crankshaft and the crankshaft-bearing in internal combustion engine, and there are the interaction effects between the crankshaft and the crankshaft-bearing during the operation of internal combustion engine.

Design/methodology/approach

The crankshaft mass and the total frictional power loss of crankshaft-bearing s are selected as the objective functions in the optimization design of crankshaft-bearing. The Particle Swarm Optimization algorithm based on the idea of decreasing strategy of inertia weight with the exponential type is used in the optimization calculation.

Findings

The total frictional power loss of crankshaft-bearing and the crankshaft mass are decreased, respectively, by 26.2 and 5.3 per cent by the multi-objective optimization design of crankshaft-bearing, which are more reasonable than the ones of single-objective optimization design in which only the crankshaft-bearing is considered as the studying object.

Originality/value

The crankshaft-bearing system of a four-cylinder internal combustion engine is taken as the studying object, and the multi-objective optimization design of crankshaft-bearing based on the crankshaft-bearing system is developed. The results of this paper are helpful to the design of the crankshaft-bearing for engine. There is universal significance to research the multi-objective optimization design of crankshaft-bearing based on the crankshaft-bearing system. The research method of the multi-objective optimization design of crankshaft-bearing based on the crankshaft-bearing system can be used to the optimization design of the bearing in the shaft-bearing system of ordinary machinery.

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