Chao Tao, Jing Wan and Jianliang Ai
The purpose of the paper is to design a robust control system for a generic hypersonic vehicle which includes dynamic nonlinear, open loop unstable and parametric uncertainties.
Abstract
Purpose
The purpose of the paper is to design a robust control system for a generic hypersonic vehicle which includes dynamic nonlinear, open loop unstable and parametric uncertainties.
Design/methodology/approach
For a complex longitudinal model of a generic hypersonic vehicle which includes dynamic nonlinear, open loop unstable and parametric uncertainties, a nonlinear dynamic inverse (NDI) approach combined with proportional differential (PD) control is used to design a strong robust control system to deal with the sensitivity to changes of atmosphere condition. In this way, a simple genetic algorithm is used to search a group of parameters of the control system to satisfy the specific performance indices. Then parametric uncertainties are considered to verify the robustness of the control system.
Findings
The PD hypersonic vehicle control system using NDI approach can satisfy the specific flight performance. And it has strong robustness under the parametric uncertainties.
Originality/value
The paper fulfills a complete process of the nonlinear control system design for a generic hypersonic vehicle. And, the simulation results show the efficiency and robustness of the control system.
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He Du, Ming Yang, Songyan Wang and Tao Chao
This paper aims to investigate a novel impact time control guidance (ITCG) law based on the sliding mode control (SMC) for a nonmaneuvering target using the predicted interception…
Abstract
Purpose
This paper aims to investigate a novel impact time control guidance (ITCG) law based on the sliding mode control (SMC) for a nonmaneuvering target using the predicted interception point (PIP).
Design/methodology/approach
To intercept the target with the minimal miss distance and desired impact time, an estimation of time-to-go is introduced. This estimation results in a precise impact time for multimissiles salvo attack the target at the same time. Even for a large lead angle, the desired impact time is achieved by using the sliding mode and Lyapunov stability theory. The singularity issue of the proposed impact time guidance laws is also analyzed to achieve an arbitrary lead angle with the desired impact time.
Findings
Numerical scenarios with desired impact time are presented to illustrate the performance of the proposed ITCG law. Comparison with the state-of-art impact time guidance laws proves that the guidance law in this paper can enable the missile to intercept the target with minimal miss distance and final impact time error. This method enables multiple missiles to attack the target simultaneously with different distances and arbitrary lead angles.
Originality/value
An ITCG law based on sliding mode and Lyapunov stability theory is proposed, and the switching surface is designed based on a novel estimation time-to-go for the missile to intercept the target with minimal miss distance. To intercept the target with initial arbitrary lead angles and desired impact time, the authors analysis the singular issue in SMC to ensure that the missile can intercept the target with arbitrary lead angle. The proposed approach for a nonmaneuvering target using the PIP has simple forms, and therefore, they have the superiority of being implemented easily.
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Cong Doanh Duong, Thanh Hieu Nguyen, Thi Viet Nga Ngo, Quang Yen Tran, Minh Hoa Nguyen and Thi Thu Phuong Pham
This research applies the stimulus-organism-behavior-consequence framework to explore how blockchain-enabled traceability influences trust in organic food producers and retailers…
Abstract
Purpose
This research applies the stimulus-organism-behavior-consequence framework to explore how blockchain-enabled traceability influences trust in organic food producers and retailers, which impacts consumers’ purchase behaviors and subsequent outcomes.
Design/methodology/approach
Using a purposive sample of 5,326 Vietnamese consumers, multiple linear and polynomial regression with response surface analysis were employed to examine the hypotheses.
Findings
Blockchain-enabled traceability significantly enhances trust in both producers and retailers, which congruently and incongruently influences organic food purchase behaviors. This behavior also drives consumers’ word-of-mouth and repurchase intentions. Serial mediation analysis confirms blockchain’s impact through trust and purchase behaviors.
Research limitations/implications
Stakeholders should adopt blockchain to boost transparency and trust, which increases consumer engagement. Policymakers can support this transition through regulations and incentives to enhance food security and sustainability.
Originality/value
This study expands on blockchain research by applying the stimulus-organism-behavior-consequence framework in the organic food supply chain, showing how blockchain-enhanced trust synergistically affects consumers’ purchase behaviors, word-of-mouth and repurchase intentions.
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Cong Doanh Duong, Thanh Hieu Nguyen, Thi Viet Nga Ngo, Thu Van Bui and Nhat Minh Tran
The current study aims to investigate the impact of perceived blockchain-related information transparency on consumers’ intention to purchase organic food. This study examines how…
Abstract
Purpose
The current study aims to investigate the impact of perceived blockchain-related information transparency on consumers’ intention to purchase organic food. This study examines how perceived blockchain- related information transparency, directly and indirectly, affects purchase intentions through attitudes, perceived behavioural control and subjective norms. Additionally, the study explores how blockchain-based trust moderates the influence of perceived blockchain-related information transparency on these factors and the intention to purchase organic food.
Design/methodology/approach
Based on the theory of planned behaviour framework and a sample of 5,326 consumers, this study uses partial least squares structural equation modelling to test the research model.
Findings
This study finds that perceived blockchain-related information transparency directly enhances consumers’ attitudes towards organic food purchase, perceived behavioural control, subjective norms and intention to purchase organic food. Additionally, perceived blockchain-related information transparency indirectly affects consumers’ intention to buy organic food through three antecedents of the theory of planned behaviour model. Notably, these indirect effects were moderated by consumers’ blockchain-based trust.
Practical implications
This study provides recommendations for leveraging blockchain to enhance transparency and build trust, which could boost consumer engagement and organic food purchases.
Originality/value
This research contributes to blockchain literature by empirically examining the role of perceived blockchain-related transparency and blockchain-based trust in consumers’ purchasing decisions regarding organic food. It provides valuable insights into the consumer-centric benefits of blockchain technology. Furthermore, this study also contributes to the literature on organic food, particularly its promotion through blockchain technology.
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Cong Doanh Duong, Thanh Hieu Nguyen, Thi Viet Nga Ngo, Tung Dao Thanh and Nhat Minh Tran
While the application of blockchain technology in the organic food supply chain has been increasingly recognized, the extant knowledge of how blockchain-driven traceability…
Abstract
Purpose
While the application of blockchain technology in the organic food supply chain has been increasingly recognized, the extant knowledge of how blockchain-driven traceability influences consumer perceptions and purchase intentions remains underexplored. Grounded in the stimulus-organism-response theory, this study aims to construct a moderated mediation model to examine blockchain-enabled traceability’s direct and indirect impacts on organic food purchase intention through perceived blockchain-related information transparency, considering the moderating role of blockchain-based trust.
Design/methodology/approach
A purposive sample of 5,326 Vietnamese consumers was surveyed using the PROCESS macro to test the proposed hypotheses.
Findings
The findings indicate that blockchain-enabled traceability significantly enhances perceived blockchain-related information transparency, which positively influences organic food purchase intention. Furthermore, blockchain-based trust was found to positively moderate both the direct effect of transparency on purchase intention and the indirect impact of traceability on purchase intention through transparency.
Practical implications
Practical and managerial insights for stakeholders in the organic food sector are also discussed.
Originality/value
These results contribute to the literature by extending the stimulus-organism-response model to the context of blockchain technology in supply chains and highlighting the critical role of trust in moderating the effectiveness of technological innovations.
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Dania Al-Najjar, Hamzeh F. Assous, Hazem Al-Najjar and Nadia Al-Rousan
This study aims to investigate the Ramadan effect anomaly on the stock markets’ indices and estimate the movement of these indices in the light of the phenomenon.
Abstract
Purpose
This study aims to investigate the Ramadan effect anomaly on the stock markets’ indices and estimate the movement of these indices in the light of the phenomenon.
Design/methodology/approach
Stock market indices are used as financial indicators to show the Ramadan effect. To validate this effect, eight Arab countries, which comprises Jordan, Saudi Arabia, Oman, Qatar, United Arab Emirates, Bahrain, Kuwait and Egypt, are adopted. A linear regression with R2, error, F-value and p-value is considered to analyze and understand the effect of Ramadan on the aforementioned Arab countries.
Findings
Results found that Ramadan has a strong effect on estimating and predicting the performance of stock market indices in all studied Arab countries, except Kuwait. Results found that the majority of the Ramadan effect occurred after the second 10 days of Ramadan, where the direction of stock indices is opposite of Ramadan variables in all aforementioned cases.
Originality/value
This study is considered as an enrichment of the existing literature review with regard to the Ramadan effect. The study presents a new methodology that can be followed to improve the predictions of stock market indices by using a weight least square method with linear regression. This study presents the most affected periods of time that could decrease or increase the stock prices. Finally, the study proves the capability of the weight least square method in building a predictive model that takes the date into consideration in predicting stock market indices.
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Chao Fan, Feng Jiang, Mingzhe Yu and Xiaobo Tao
Brand storytelling is an effective marketing tool. However, when choosing whether to tell more or tell less, it remains unclear which of these two narrative styles is most…
Abstract
Purpose
Brand storytelling is an effective marketing tool. However, when choosing whether to tell more or tell less, it remains unclear which of these two narrative styles is most effective. This study aims to examine whether blank-leaving(less) leads to favourable brand attitudes and compares its effects on consumers’ story immersion, to non-blank-leaving(more).
Design/methodology/approach
Two experiments were conducted to test the hypotheses. In Study 1, a single-factorial design was used with 252 participants assigned at random to one of two narrative conditions: blank-leaving or non-blank-leaving. Study 2 replicated Study 1 and investigated the moderating role of implicit mindsets.
Findings
The results show that a blank-leaving narrative style increases favourable brand attitudes. Consumers present deeper immersion in the brand story that uses blank-leaving, as compared to non-blank-leaving, leading to a more favourable brand attitude. Furthermore, this effect is stronger for individuals with growth mindsets.
Practical implications
Telling the brand story using a blank-leaving narrative style is more effective in catching consumers’ attention than non-blank-leaving. In particular, a blank-leaving narrative is a good approach for targeting consumers who have a growth mindset.
Originality/value
To the best of the authors’ knowledge, this research is the first to investigate and compare the effects of blank-leaving and non-blank-leaving narrative styles on brand attitudes in the context of storytelling marketing.
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Shih‐Lin Wu, Jang‐Ping Sheu and Chung‐Chao Lee
This paper proposes a distributed multi‐channel MAC protocol which is an extension of our early work GRID [1]. GRID is characterized by the following features: (i) it integrates a…
Abstract
This paper proposes a distributed multi‐channel MAC protocol which is an extension of our early work GRID [1]. GRID is characterized by the following features: (i) it integrates a location‐aware channel assignment, (ii) it follows an “on‐demand” style to access the medium, (iii) the number of channels required is independent of the network topology, and (iv) no form of clock synchronization is required. The proposed protocol wants to further improve the GRID in two parts. First, we propose a fully distributed medium access mechanism without using a single control channel such that all of the network traffic can be distributed evenly over all data channels. Therefore, the network throughput will be increased significantly. Second, we can set the more suitable transmission range and GRID size by considering the factors of host density and packet arrival rate of the network within an specified area. Thus, all of channels will be reused more efficiently than GRID. Simulation results show that the throughput of our protocol is superior to GRID and IEEE 802.11.
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Yao Chao, Tao Liu and Liming Shen
This study aimed to develop a method to calculate the mattress indentation for further estimating spinal alignment.
Abstract
Purpose
This study aimed to develop a method to calculate the mattress indentation for further estimating spinal alignment.
Design/methodology/approach
A universal indentation calculation model is derived based on the system theory, and the deformation characteristics of each component are analyzed by the finite element (FE) model of a partial air-spring mattress under the initial air pressure of 0.01–0.025 MPa. Finally, the calculation error of the model is verified.
Findings
The results indicate that the indentation calculation model could describe the stain of a mattress given the load and the constitutive model of each element. In addition, the FE model of a partial air-spring mattress can be used for further simulation analysis with an error of 1.47–3.42 mm. Furthermore, the deformation of the series system is mainly contributed by the air spring and the components directly in contact with it, while the top component is mainly deflection deformation. In addition, the error of the calculation model is 2.17–5.59 mm on the condition of 0.01–0.025 MPa, satisfying the engineering application. Finally, the supine spinal alignment is successfully extracted from the mattress indentation.
Research limitations/implications
The limitation of this study is that it needs to verify the practicality of the indentation calculation model for the Bonnier spiral spring mattress. The main feature of the Bonnier spring mattress is that all springs are connected, so the mattress deflection and neighborhood effect are more significant than those of the air-spring mattress. Therefore, the applicability of the model needs to be tested. Moreover, it is worth further research to reduce the deformation error of each component.
Practical implications
As part of the series of studies on the intelligent air-spring mattress, the indentation-based evaluation method of spinal alignment in sleep postures will be studied for hardness and intelligent regulation based on this study.
Social implications
The results of this research are ultimately used for the intelligent adjustment of air-spring mattresses, which automatically adjusts the hardness according to the user's sleep postures and spinal alignment, thus maintaining optimal spinal biomechanics. The successful application of this result could improve the sleep health of the general public.
Originality/value
Based on the series system theory, an indentation calculation model for mattresses with arbitrary structure is proposed, overcoming the dependence of parameters on materials and their combinations when fitting the Burgers model. Further, the spinal alignment in supine posture is extracted from the indentation, laying a theoretical foundation for further recognition and adjustment of the spinal alignment of the intelligent mattress.