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This paper aims to propose and verify an improved cascade active disturbance rejection control (ADRC) scheme based on output redefinition for hypersonic vehicles (HSVs) with nonminimum phase characteristic and model uncertainties.

To handle the nonminimum phase characteristic, a tuning factor stabilizing internal dynamics is introduced to redefine the system output states; its effective range is determined by analyzing Byrnes–Isidori normalized form of the redefined system. The extended state observers (ESOs) are used to estimate the uncertainties, which include matched and mismatched items in the system. The controller compensates observations in real time and appends integral terms to improve robustness against the estimation errors of ESOs.

Theoretical and simulation results show that the stability of internal dynamics is guaranteed by the tuning factor and the tracking errors of external commands are globally asymptotically stable.

The control scheme in this paper is expected to generate a reliable way for dealing with nonminimum phase characteristic and model uncertainties of HSVs.

In the framework of ADRC, a concise form of redefined outputs is proposed, in which the tuning factor performs a decisive role in stabilizing the internal dynamics of HSVs. By introducing an integral term into the cascade ADRC scheme, the compensation accuracy of matched and mismatched disturbances is improved.

This paper introduces control strategy to enhance the performance of a novel quadrotor unmanned aerial vehicle designed for medical payload delivery. The aim is to achieve precise control and stability when carrying and releasing payloads, which alter the quadrotor’s mass and inertia characteristics.

The equations of motion specific to the payload-carrying quadrotor are derived. A feedforward-proportional-integral-derivative (FF-PID) control strategy is then proposed to address the dynamic changes during payload release. The PID components use propeller speed/orientation information for stability. FF terms based on derivatives of desired position/orientation variables enable adaptation to real-time mass fluctuations.

Extensive simulations, encompassing various fault scenarios, substantiate the effectiveness of the FF-PID approach. Notably, our findings demonstrate superior performance in maintaining altitude precision and stability during critical phases such as takeoff, payload release and landing. Graphical representations of thrust and mass dynamics distinctly illustrate the payload release event. In contrast to the linear quadratic regulator (LQR) and conventional PID control, which encountered difficulties during the payload release process, our approach proves its robustness and reliability.

This study, primarily based on simulations, demands validation through real-world testing in diverse conditions. Uncertainties in dynamic parameters, external factors and the applicability of the proposed approach to other quadrotor configurations require further investigation. Additionally, this research focuses on controlled payload release, leaving unexplored the challenges posed by unforeseen scenarios or disturbances. Hence, adaptability and fault tolerance necessitate further exploration. While our work presents a promising approach, practical implementation, adaptability and resilience to unexpected events are vital considerations for future research in the field of autonomous aerial medical deliveries.

The proposed control strategy promises enhanced efficiency, reliability and adaptability for autonomous aerial medical deliveries in critical scenarios.

The innovative control strategy introduced in this study holds the potential to significantly impact society by enhancing the reliability and adaptability of autonomous aerial medical deliveries. This could lead to faster and more efficient delivery of life-saving supplies to remote or disaster-affected areas, ultimately saving lives and reducing suffering. Moreover, the technology’s adaptability may have broader applications in fields like disaster relief, search and rescue missions, and industrial cargo transport. However, its successful integration into society will require careful regulation, privacy safeguards and ethical considerations to ensure responsible and safe deployment while addressing potential concerns related to noise pollution and privacy intrusion.

While PID control of quadrotors is extensively studied, payload release dynamics have been overlooked. This research studies integration of FF control to enable PID adaptation for a novel payload delivery application.

This paper aims to help workplace ethnographers navigate and reflect on primary access negotiations by scrutinising two of the concepts mentioned in the call for papers on this special issue: workplace relations and tensions. We introduce the frames of reference (FoRs) concept as used in the field of employment relations to the ethnographic community. We propose that the implicit frames of gatekeeper and researcher influence what they deem interesting for research, thus influencing the content of access negotiations. Moreover, we propose that tensions typically emerge when gatekeepers and ethnographers do not share the same frame of the employment relationship (ER).

We explore the ER through Fox’s (1966, 1974) framework, taking inspiration from Budd et al. (2022), who applied FoRs to employer–employee relations. We adapt the framework to the relationships between workplace ethnographers and gatekeepers by theorising the characteristics of ideal types of gatekeepers and workplace ethnographers and exploring possible implications for when they meet in access negotiations. We distil lessons learnt from previous research by drawing on illustrative examples from the literature to suggest strategies for interacting with gatekeepers when tensions emerge, providing a pragmatic application of our contribution.

Assuming that their FoR of the ER contributes to what they find to be of practical relevance/academic interest, we suggest that a (mis)match of gatekeepers’ and workplace ethnographers’ FoRs can lead to tensions between workplace ethnographers and gatekeepers, either remaining latent or becoming salient. We propose three possible strategies as to how to navigate these tensions during primary access negotiations.

Whilst previous research has mainly focused on the ethnographer as an individual who needs to give gatekeepers a reassuring and enticing impression, we discuss how an important structural factor, an organisation’s ER setup, may influence access. We thus bring an important yet hitherto neglected aspect of organisational life into the debate on the pragmatic realities of ethnography, contributing to the discussion of how to navigate the tension between the “practical” need to convince gatekeepers and the need to fulfil one’s own standards of rigorous research and ethics.

The current adverse changes in climatic conditions have necessitated innovative nature-based solutions like blue-green roofs to ensure sustainable built environments. The use of blue-green roofs in combating climate change issues has continued to grow, and its benefits are showcased in many countries' studies. However, there is an absence of reports on the use of this approach in South Africa. Therefore, in ensuring a sustainable built environment through nature-based solutions, this study explored the built environment professional’s knowledge of blue-green roofs, the hindrances to their use and motivations for much wider use of blue-green roofs in the country.

Based on the nature of the study, a quantitative design was adopted and data were obtained from professionals within the built environment through a questionnaire. Data analyses were conducted using the Cronbach alpha test, Kruskal–Wallis H-Test, exploratory factor analysis and fuzzy synthetic evaluation.

The findings revealed a growing knowledge of blue-green roofs, albeit its slow adoption in the country. Also, five critical clusters of hindrances affecting the use of blue-green roofs were identified. These are understanding the blue-green roof concepts, technical, economic, regulation and client hindrances. Furthermore, the ability to manage stormwater properly, provide climate change adaptation and deliver sustainable buildings were the key motivating factors that could drive the use of this innovative solution.

This study offers actionable insights for built environment professionals and stakeholders to address the hindrances to using blue-green roofs in South Africa. Strategies such as improved education, financial incentives and policy development can help overcome some notable hindrances and promote the widespread adoption of blue-green roofs.

The slow adoption of blue-green roofs and the scant nature of research within the built environment required adequate attention to which this current research contributes. Theoretically, being one of the foremost studies in South Africa to explore blue-green roofs, the findings offer a foundation for future studies seeking to explore this roofing system in the country further.

This study examines the effect of the spiritual leadership of the leaders in a consulting team on psychological safety climate and team innovation. Moreover, our research adopts the contingency theory of leadership to investigate whether the effect of spiritual leadership on psychological safety climate and team innovation could be moderated by personal characteristics of team members in terms of occupational self-efficacy.

Survey data were obtained from 229 team members across 24 consulting firms in Bangkok. To minimize common method bias, team innovation was assessed by team leaders while other variables were assessed by team members. We used Partial Least Squares Structural Equation Modeling to analyze the data.

The analysis supports the positive effect of spiritual leadership on psychological safety climate and team innovation. Psychological safety climate also mediates the effect of spiritual leadership on team innovation. Lastly, the moderating effect analysis shows that the spiritual leadership of the team leaders exerts a weaker influence on the psychological safety climate and team innovation when team members exhibit high levels of occupational self-efficacy.

Because spiritual leadership plays a significant role in boosting team innovation through the creation of a psychologically safe climate, the consulting firms can provide a leadership development program to help their team leaders to gain insight into the nature of spiritual leadership and learn how to demonstrate appropriate behaviors when they supervise a team. In particular, this policy recommendation is highly relevant when team leaders supervise members who exhibit low occupational self-efficacy.

Our findings not only illustrate that spiritual leadership could enhance team innovation through the mediating role of psychological safety climate, but the level of occupational self-efficacy of the team members could significantly reduce the effects of spiritual leadership on psychological safety climate and team innovation.

In the context of rewards-based crowdfunding, this study aims to examine the role of project backers as providers of knowledge inputs beyond just financial capital.

This study uses binomial regression to study the relationship between project creators’ and backers’ knowledge sharing, and the relationship of these two knowledge-sharing elements with achieving above-goal funding levels.

This study finds that the project creator’s knowledge sharing is significantly and positively related to backers’ knowledge sharing and that this relationship is moderated by the type of project. Furthermore, backers’ knowledge sharing is positively related to above-goal funding outcomes for a project.

This study established the link between creators’ and backers’ knowledge sharing in rewards-based crowdfunding, which has been underexplored in the literature. This study’s direct attention to the role of knowledge as a key resource in rewards-based crowdfunding and crowdsourcing in general.

For entrepreneurs seeking crowdfunding, this study highlights the importance of knowledge sharing with their project backers to attain above-goal funding. Furthermore, eliciting backers’ knowledge input acts as a signaling mechanism that increases the crowd’s confidence in the project. It also endows entrepreneurs with knowledge resources that can improve project outcomes and achieve broader market success postcrowdfunding.

To the best of the authors’ knowledge, this study is one of the first to focus on knowledge content as a critical element in project backer-creator communication in rewards-based crowdfunding. This study also delineate the various knowledge types shared between the project creator and backers in both rewards-based crowdfunding projects.