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As the number of social media users continues to rise globally, a heated debate emerges on whether social media use improves or harms mental health, as well as the bidirectional relation between social media use and mental health. Motivated by this, the authors’ study adopts the stressor–strain–outcome model and social compensation hypothesis to disentangle the effect mechanism between social media use and psychological well-being. The purpose of this paper is to address this issue.

To empirically validate the proposed research model, a large-scale two-year longitudinal questionnaire survey on social media use was administered to a valid sample of 6,093 respondents recruited from a university in China. Structural equation modeling was employed for data analysis.

A longitudinal analysis reveals that social media use positively (negatively) impacts psychological well-being through the mediator of nomophobia (perceived social support) in a short period. However, social media use triggers more psychological unease, as well as more life satisfaction from a longitudinal perspective.

This study addresses the bidirectional relation between social media use and psychological unease. The current study also draws both theoretical and practical implications by unmasking the bright–dark duality of social media use on psychological well-being.

Building information modelling (BIM), lean construction (LC) and prefabricated housing construction (PHC) have individually aroused great attention from academia and industry. However, the integration of LC and BIM in PHC projects has not been sufficiently explored. This study aims to assess the current status of the implementation of BIM and LC in China’s PHC sector given, firstly, that China is a developing country characterised by the world’s largest population and a huge housing market, and secondly, that although China’s PHC is strongly supported by the government, the adoption of BIM and LC in PHC varies.

A mixed approach (questionnaire survey and interviews) is adopted in this study. A total of 127 valid questionnaires were collected. This is followed by interviewing 12 interviewees who are key stakeholders in PHC and hold managerial positions.

The findings of the questionnaire survey show that BIM is more prevalent than LC in PHC projects in China. In addition, the adoption of LC exhibits more maturity in stages associated with production and manufacturing, and logistics and transportation, whereas BIM has seen wider adoption in design and construction. The interviews validated the factors that influence the implementation of BIM and LC in PHC projects in China.

The study uses a strengths, weaknesses, opportunities and threats analysis framework to clarify the opportunities, threats, strengths and weaknesses of BIM and LC in China’s PHC and proposes strategies.

Online question-and-answer (Q&A) communities serve as important channels for knowledge diffusion. The purpose of this study is to investigate the dynamic development process of online knowledge systems and explore the final or progressive state of system development. By measuring the nonlinear characteristics of knowledge systems from the perspective of complexity science, the authors aim to enrich the perspective and method of the research on the dynamics of knowledge systems, and to deeply understand the behavior rules of knowledge systems.

The authors collected data from the programming-related Q&A site Stack Overflow for a ten-year period (2008–2017) and included 48,373 tags in the analyses. The number of tags is taken as the time series, the correlation dimension and the maximum Lyapunov index are used to examine the chaos of the system and the Volterra series multistep forecast method is used to predict the system state.

There are strange attractors in the system, the whole system is complex but bounded and its evolution is bound to approach a relatively stable range. Empirical analyses indicate that chaos exists in the process of knowledge sharing in this social labeling system, and the period of change over time is about one week.

This study contributes to revealing the evolutionary cycle of knowledge stock in online knowledge systems and further indicates how this dynamic evolution can help in the setting of platform mechanics and resource inputs.

Building on social media and destination brand-related literature, this study aims to explore World Heritage Sites’ (WHSs) brand diffusion and formation process from long-term and short-term perspectives, which includes brand diffusion, user-generated content (UGC), opinion leaders and brand events’ impact.

This study uses a mixed-method including text mining, keyword analysis and social network analysis to explore the brand formation process of four popular WHSs in Beijing, namely, the Palace Museum, Great Wall, Summer Palace and Temple of Heaven and more than 10,000,000 users’ data on Sina Weibo has been implemented to uncover the underlying social media branding mechanism.

The results show that the number of postings keeps in a stable range in most months, but, in general, there are no common rules for changing trends among the four WHSs; long-term high-frequency keywords related to history and culture account for a higher percentage; different kinds of accounts have varying impacts on information diffusion, in which media accounts lead to a bigger influence. However, more followers do not necessarily mean more interactions and most of the interaction ratio is much lower than 0.01000; brand events facilitate brand dissemination and have an impact on the creation of UGC.

This study is valuable for destination marketers to deeper understand brand diffusion and formation and provides valuable insights for developing effective destination marketing strategies.

Unlike previous studies that only concern a few parts of destination brand formation via social media (e.g. brand diffusion, brand events or opinion leaders’ impact), this study takes a more comprehensive perspective by systematically analyzing the brand formation process of WHSs on social media. By considering both long-term diffusion and short-term representative events, this study provides a more holistic understanding of the branding mechanism.

The purpose of this paper is to introduce an improved system identification method for small unmanned helicopters combining adaptive ant colony optimization algorithm and Levy’s method and to solve the problem of low model prediction accuracy caused by low-frequency domain curve fitting in the small unmanned helicopter frequency domain parameter identification method.

This method uses the Levy method to obtain the initial parameters of the fitting model, uses the global optimization characteristics of the adaptive ant colony algorithm and the advantages of avoiding the “premature” phenomenon to optimize the initial parameters and finally obtains a small unmanned helicopter through computational optimization Kinetic models under lateral channel and longitudinal channel.

The algorithm is verified by flight test data. The verification results show that the established dynamic model has high identification accuracy and can accurately reflect the dynamic characteristics of small unmanned helicopter flight.

This paper presents a novel and improved frequency domain identification method for small unmanned helicopters. Compared with the conventional method, this method improves the identification accuracy and reduces the identification error.

A switching depth controller based on a variable buoyancy system (VBS) is proposed to improve the performance of small autonomous underwater vehicles (AUVs). First, the requirements of VBS for small AUVs are analyzed. Second, a modular VBS with high extensibility and easy integration is proposed based on the concepts of generality and interchangeability. Subsequently, a depth-switching controller is proposed based on the modular VBS, which combines the best features of the linear active disturbance rejection controller and the nonlinear active disturbance rejection controller.

The controller design and endurance of tiny AUVs are challenging because of their low environmental adaptation, limited energy resources and nonlinear dynamics. Traditional and single linear controllers cannot solve these problems efficiently. Although the VBS can improve the endurance of AUVs, the current VBS is not extensible for small AUVs in terms of the differences in individuals and operating environments.

The switching controller’s performance was examined using simulation with water flow and external disturbances, and the controller’s performance was compared in pool experiments. The results show that switching controllers have greater effectiveness, disturbance rejection capability and robustness even in the face of various disturbances.

A high degree of standardization and integration of VBS significantly enhances the performance of small AUVs. This will help expand the market for small AUV applications.

This solution improves the extensibility of the VBS, making it easier to integrate into different models of small AUVs. The device enhances the endurance and maneuverability of the small AUVs by adjusting buoyancy and center of gravity for low-power hovering and pitch angle control.

The architecture, engineering and construction (AEC) industry encounter substantial risks and challenges in its evolution towards sustainable development. International businesses, multinational AEC organisations, technical professionals, project and portfolio management organisations face global connectivity challenges between business units, especially during the outbreak of novel coronavirus pandemic, to manage construction megaprojects (CMPs). That raises the need to manage global connectivity as a main strategic goal of global organisations. This paper aims to investigate barriers to integrating lean construction (LC) practices and integrated project delivery (IPD) on CMPs towards the global integrated delivery (GID) transformative initiatives and develop future of work (FOW) global initiatives in contemporary multinational AEC organisations.

A two-stage quantitative and qualitative research approach is adopted. The qualitative research methodology consists of a literature review to appraise barriers to integrating LeanIPD&GID on CMPs. Barriers are arranged into six-factor clusters (FCs), with a conceptualisation of LeanIPD&GID, GID strategy placements and FOW global initiatives with multiple validations. This analysis also involved semi-structured interviews and focus group techniques. Stage two consisted of an empirical questionnaire survey that shaped the foundation of analysis and findings of 230 respondents from 23 countries with extensive cosmopolitan experience in the construction of megaprojects. The survey examined a set of 28 barriers to integrating LeanIPD&GID on CMPs resulting from a detailed analysis of extant literature after validation. Descriptive and inferential statistical tests were exploited for data analysis, percentage scoring analysis, principal component analysis (PCA) and eigenvalues were used to elaborate on clustered factors.

The research conceptualised LeanIPD&GID principles and proposed GID strategy placements for LeanIPD&GID transformative initiatives and FOW global initiatives. It concluded that the most significant barriers to integration of LeanIPD&GID on CMPs are “lack of mandatory building information modelling (BIM) and LC industry standards and regulations by governments”, “lack of involvement and support of governments”, “high costs of BIM software licenses”, “resistance of industry to change from traditional working practices” and “high initial investment in staff training costs of BIM”. PCA revealed the most significant FCs are “education and knowledge-related barriers”, “project objectives-related barriers” and “attitude-related barriers”. Awareness of BIM in the Middle East and North Africa (MENA) region is higher than LC and LC awareness is higher than IPD knowledge. Whilst BIM adoption in the MENA region is higher than LC; the second is still taking its first steps, whilst IPD has little implementation. LeanBIM is slightly integrated, whilst LeanIPD integration is almost not present.

The research findings, conclusion and recommendation and proposed GID strategy placements for LeanIPD&GID transformative initiatives to integrating LeanIPD&GID on CMPs. This will allow project key stakeholders to place emphasis on tackling LeanIPD&GID barriers identified in this research and commence GID strategies. The study has provided effective practical strategies for enhancing the integration of LeanIPD&GID transformative initiatives on CMPs.

Integrated project delivery (IPD) has attracted considerable attention in recent years, however only a few review studies captured the dynamic and evolving nature of this topic. The purpose of this study is to review the most recent IPD publications, in order to shed light on future research.

Using a systematic review methodology, the study aims to synthesize the current IPD literature, and frame the latest research and development in this domain. A systematic review is conducted to identify the current state-of-the-art of IPD research and the latest research themes and trends in this domain. A bibliometric analysis is performed to explain characteristics of screened articles, and through a thematic analysis the latest themes and trends are recognized.

In this study, based on IPD characteristics (contractual-regulative, operational-cognitive and organizational-structural), research themes (legal, commercial, technological, procedural, cultural and structural), sub-themes and their associated trends are identified. The latest emerging trends are mostly related to the contractual characteristics of IPD, and are focused on the combination of IPD with new business models and developing contractual guidelines for promoting IPD applications in off-site and on-site construction projects.

This research contributes to the body of knowledge by synthesizing the state of the art of IPD in construction literature and exposing the latest research trends in this area. A theoretical framework of integration in an IPD context is developed, based on the literature. Finally, future areas of studies are discussed.