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Article
Publication date: 12 August 2021

Guoda Wang, Ping Li, Yumei Wen and Zhichun Luo

Existing control circuits for piezoelectric energy harvesting (PEH) suffers from long startup time or high power consumption. This paper aims to design an ultra-low power…

Abstract

Purpose

Existing control circuits for piezoelectric energy harvesting (PEH) suffers from long startup time or high power consumption. This paper aims to design an ultra-low power control circuit that can harvest weak ambient vibrational energy on the order of several microwatts to power heavy loads such as wireless sensors.

Design/methodology/approach

A self-powered control circuit is proposed, functioning for very brief periods at the maximum power point, resulting in a low duty cycle. The circuit can start to function at low input power thresholds and can promptly achieve optimal operating conditions when cold-starting. The circuit is designed to be able to operate without stable DC power supply and powered by the piezoelectric transducers.

Findings

When using the series-synchronized switch harvesting on inductor circuit with a large 1 mF energy storage capacitor, the proposed circuit can perform 322% better than the standard energy harvesting circuit in terms of energy harvested. This control circuit can also achieve an ultra-low consumption of 0.3 µW, as well as capable of cold-starting with input power as low as 5.78 µW.

Originality/value

The intermittent control strategy proposed in this paper can drastically reduce power consumption of the control circuit. Without dedicated cold-start modules and DC auxiliary supply, the circuit can achieve optimal efficiency within one input cycle, if the input signal is larger than voltage threshold. The proposed control strategy is especially favorable for harvesting energy from natural vibrations and can be a promising solution for other PEH circuits as well.

Details

Circuit World, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 November 2021

Dongwon Choi and Jooyoung Kim

The primary purpose of the current study was to examine how the presence of two digital ad features – an ad skip option and an ad time display, representing behavioral and…

Abstract

Purpose

The primary purpose of the current study was to examine how the presence of two digital ad features – an ad skip option and an ad time display, representing behavioral and cognitive control, respectively – might influence viewer response to in-stream video ads in terms of perceived control, reactance and advertising outcomes.

Design/methodology/approach

A 2 (Ad skip option: presence vs. absence) × 2 (Ad time display: presence vs absence) between-subjects experiment was conducted online with 217 participants recruited via Qualtrics.

Findings

The results of the online experiment show that the presence of the ad skip option and ad time display related to a higher level of perceived control, predicting lower ad intrusiveness and ad irritation and more favorable attitude toward the ad.

Practical implications

The findings confirm that an ad skip option and an ad time display could minimize negative responses to in-stream video ads by increasing perceived control and reducing viewer reactance.

Originality/value

The findings provide empirical evidence that multiple dimensions of control features (i.e. behavioral and cognitive) can increase perceived control and strengthen its impact on advertising outcomes.

Details

Internet Research, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1066-2243

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Article
Publication date: 12 October 2021

Shovan Chowdhury, Amarjit Kundu and Bidhan Modok

As an alternative to the standard p and np charts along with their various modifications, beta control charts are used in the literature for monitoring proportion data…

Abstract

Purpose

As an alternative to the standard p and np charts along with their various modifications, beta control charts are used in the literature for monitoring proportion data. These charts in general use average of proportions to set up the control limits assuming in-control parameters known. The purpose of the paper is to propose a control chart for detecting shift(s) in the percentiles of a beta distributed process monitoring scheme when in-control parameters are unknown. Such situations arise when specific percentile of proportion of conforming or non-conforming units is the quality parameter of interest.

Design/methodology/approach

Parametric bootstrap method is used to develop the control chart for monitoring percentiles of a beta distributed process when in-control parameters are unknown. Extensive Monte Carlo simulations are conducted for various combinations of percentiles, false-alarm rates and sample sizes to evaluate the in-control performance of the proposed bootstrap control charts in terms of average run lengths (ARL). The out-of-control behavior and performance of the proposed bootstrap percentile chart is thoroughly investigated for several choices of shifts in the parameters of beta distribution. The proposed chart is finally applied to two skewed data sets for illustration.

Findings

The simulated values of in-control ARL are found to be closer to the theoretical results implying that the proposed chart for percentiles performs well with both positively and negatively skewed data. Also, the out-of-control ARL values for the percentiles decrease sharply with both downward and upward small, medium and large shifts in the parameters. The phenomenon indicates that the chart is effective in detecting shifts in the parameters. However, the speed of detection of shifts varies depending on the type of shift, the parameters and the percentile being considered. The proposed chart is found to be effective in comparison to the Shewhart-type chart and bootstrap-based unit gamma chart.

Originality/value

It is worthwhile to mention that the beta control charts proposed in the literature use average of proportion to set up the control limits. However, in practice, specific percentile of proportion of conforming or non-conforming items should be more useful as the quality parameter of interest than average. To the best of our knowledge, no research addresses beta control chart for percentiles of proportion in the literature. Moreover, the proposed control chart assumes in-control parameters to be unknown, and hence captures additional variability introduced into the monitoring scheme through parameter estimation. In this sense, the proposed chart is original and unique.

Details

International Journal of Quality & Reliability Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0265-671X

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Article
Publication date: 29 October 2021

Sine Yılmaz, Nevin Sanlier, Pınar Göbel, Büşra Açıkalın, Sule Kocabas and Akif Dundar

Staying at home for a prolonged period, the stress during COVID-19 quarantine may affect sleep quality, night eating behaviours of individuals. This paper aims to identify…

Abstract

Purpose

Staying at home for a prolonged period, the stress during COVID-19 quarantine may affect sleep quality, night eating behaviours of individuals. This paper aims to identify the relationship between night eating behaviour, sleep quality, perceptions of health locus of control in women during the pandemic.

Design/methodology/approach

An anonymous, Web based, cross-sectional study was conducted for the duration of a month (April-May, 2020). The study evaluated the nutritional habits of the participants. Anthropometric measurements were noted. Night Eating Syndrome Questionnaire (NESQ), Pittsburgh Sleep Quality Index (PSQI), Multi-dimensional Health Locus of Control-A were used for data collection.

Findings

With a mean age of 33 ± 8 years, 529 women participated in the study. The mean NESQ score was 14.4 ± 4.7, PSQI score was 6.4 ± 2.9. Higher night eating scores were observed in participants with chance locus of control (CLC) perception when compared to participants with internal health locus of control (IHLC) perception (p < 0.05). Lower sleep quality was observed in obese participants compared to normal/overweight participants (p < 0.05). It was also found that night eating behaviours significantly predicted sleep quality (R = 0.36, R2 = 0.13; p < 0.01), explaining about 13.3% of total variance of sleep quality.

Research limitations/implications

Only internet users and women participated in the study, and the questionnaire form was applied online; the information was obtained in the form of the participants' own statements.

Practical implications

It was found that night eating behaviour significantly predicted sleep quality during the pandemic. It was also determined that the individuals with high chance locus of control perception had higher NES scores than the individuals with high internal locus of control perception.

Originality/value

The night eating behaviours significantly predict sleep quality, individuals with a high perception of CLC had a higher night eating score than individuals with high perception of IHLC during the pandemic.

Details

Nutrition & Food Science , vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0034-6659

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Article
Publication date: 12 October 2021

Cong Doanh Duong

The purpose of this research is to integrate the prediction from entrepreneurship education with the theory of planned behaviors (TPB) to build a conceptual framework and…

Abstract

Purpose

The purpose of this research is to integrate the prediction from entrepreneurship education with the theory of planned behaviors (TPB) to build a conceptual framework and estimate the effect of entrepreneurship education on entrepreneurial intention over and above key predictors from an extended TPB model. Also, the moderating impacts of educational fields in the paths from entrepreneurial education, attitude toward entrepreneurship, subjective norms and perceived behavioral control to entrepreneurial intention are tested in this study.

Design/methodology/approach

The study used a sample of 559 university students who received entrepreneurship education at 12 universities from Vietnam. Confirmatory factor analysis was utilized to test the validity and reliability of all variables and regression analyses were used to estimate coefficient paths. Then, bootstrapping method with the PROCESS approach was utilized to test the indirect correlations.

Findings

The study reveals that attitude toward entrepreneurship and perceived behavioral control were positively and strongly associated with entrepreneurial intention, while the linkage between subjective norms and entrepreneurial intention was not significant. Also, the findings show that even though entrepreneurship education did not have a direct effect on entrepreneurial intention, it increased entrepreneurial intention via attitude toward entrepreneurship and perceived behavioral control. In addition, this study finds that educational fields moderate the associations between predictors and entrepreneurial intention.

Practical implications

This study offers both universities and policymakers options to foster youths' entrepreneurial activities.

Originality/value

This study is expected to significantly contribute to entrepreneurship literature by enriching our understanding of the interesting and crucial linkages between entrepreneurship education, attitude toward entrepreneurship, subjective norms, perceived behavioral control and entrepreneurial intention. Additionally, the current research reveals that for economic and business management students, the paths are driven from entrepreneurial education, attitude toward entrepreneurship, subjective norms and perceived behavioral control to intention to engage in entrepreneurial activities has become stronger when compared to students of majors in engineering and others.

Details

Education + Training, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0040-0912

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Article
Publication date: 18 October 2021

Zafer Bingul and Oguzhan Karahan

The purpose of this paper is to address a fractional order fuzzy PID (FOFPID) control approach for solving the problem of enhancing high precision tracking performance and…

Abstract

Purpose

The purpose of this paper is to address a fractional order fuzzy PID (FOFPID) control approach for solving the problem of enhancing high precision tracking performance and robustness against to different reference trajectories of a 6-DOF Stewart Platform (SP) in joint space.

Design/methodology/approach

For the optimal design of the proposed control approach, tuning of the controller parameters including membership functions and input-output scaling factors along with the fractional order rate of error and fractional order integral of control signal is tuned with off-line by using particle swarm optimization (PSO) algorithm. For achieving this off-line optimization in the simulation environment, very accurate dynamic model of SP which has more complicated dynamical characteristics is required. Therefore, the coupling dynamic model of multi-rigid-body system is developed by Lagrange-Euler approach. For completeness, the mathematical model of the actuators is established and integrated with the dynamic model of SP mechanical system to state electromechanical coupling dynamic model. To study the validness of the proposed FOFPID controller, using this accurate dynamic model of the SP, other published control approaches such as the PID control, FOPID control and fuzzy PID control are also optimized with PSO in simulation environment. To compare trajectory tracking performance and effectiveness of the tuned controllers, the real time validation trajectory tracking experiments are conducted using the experimental setup of the SP by applying the optimum parameters of the controllers. The credibility of the results obtained with the controllers tuned in simulation environment is examined using statistical analysis.

Findings

The experimental results clearly demonstrate that the proposed optimal FOFPID controller can improve the control performance and reduce reference trajectory tracking errors of the SP. Also, the proposed PSO optimized FOFPID control strategy outperforms other control schemes in terms of the different difficulty levels of the given trajectories.

Originality/value

To the best of the authors’ knowledge, such a motion controller incorporating the fractional order approach to the fuzzy is first time applied in trajectory tracking control of SP.

Details

Industrial Robot: the international journal of robotics research and application, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0143-991X

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Article
Publication date: 27 October 2021

Yanxi Li and Shanshan Ouyang

The purpose of this study is to examine the impact of controlling shareholders’ share pledging on goodwill impairment.

Abstract

Purpose

The purpose of this study is to examine the impact of controlling shareholders’ share pledging on goodwill impairment.

Design/methodology/approach

This study empirically investigates the effect of controlling shareholders’ share pledging on both the decision and amount of goodwill impairment for Chinese listed firms from 2007 to 2017.

Findings

This study finds that the proportion of controlling shareholders’ share pledging is negatively related to both impairment decisions and amounts; these negative relationships are intensified when firms face high stock price crash risks. In addition, the empirical results show that firms with larger share pledging are less likely to recognize goodwill impairment or are likely to record relatively smaller impairment amounts when they are followed by fewer financial analysts.

Originality/value

Most of the relevant literature has focused on managers’ behaviors toward goodwill impairments, while less attention has been given to goodwill impairments from the perspective of controlling shareholders. In fact, controlling shareholders may have strong incentives to protect their control rights when they exercise disproportionate control rights, especially in China. Given the high ownership concentration, prior studies may not have adequately explained the agency problem of controlling shareholders in goodwill impairment. This study uses share pledging as a case to fill this gap. Specifically, it investigates whether both goodwill impairment decisions and amounts are affected by controlling shareholders’ share pledging.

Details

International Journal of Accounting & Information Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1834-7649

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Article
Publication date: 13 October 2021

Liang Su, Zhenpo Wang and Chao Chen

The purpose of this study is to propose a torque vectoring control system for improving the handling stability of distributed drive electric buses under complicated…

Abstract

Purpose

The purpose of this study is to propose a torque vectoring control system for improving the handling stability of distributed drive electric buses under complicated driving conditions. Energy crisis and environment pollution are two key pressing issues faced by mankind. Pure electric buses are recognized as the effective method to solve the problems. Distributed drive electric buses (DDEBs) as an emerging mode of pure electric buses are attracting intense research interests around the world. Compared with the central driven electric buses, DDEB is able to control the driving and braking torque of each wheel individually and accurately to significantly enhance the handling stability. Therefore, the torque vectoring control (TVC) system is proposed to allocate the driving torque among four wheels reasonably to improve the handling stability of DDEBs.

Design/methodology/approach

The proposed TVC system is designed based on hierarchical control. The upper layer is direct yaw moment controller based on feedforward and feedback control. The feedforward control algorithm is designed to calculate the desired steady-state yaw moment based on the steering wheel angle and the longitudinal velocity. The feedback control is anti-windup sliding mode control algorithm, which takes the errors between actual and reference yaw rate as the control variables. The lower layer is torque allocation controller, including economical torque allocation control algorithm and optimal torque allocation control algorithm.

Findings

The steady static circular test has been carried out to demonstrate the effectiveness and control effort of the proposed TVC system. Compared with the field experiment results of tested bus with TVC system and without TVC system, the slip angle of tested bus with TVC system is much less than without TVC. And the actual yaw rate of tested bus with TVC system is able to track the reference yaw rate completely. The experiment results demonstrate that the TVC system has a remarkable performance in the real practice and improve the handling stability effectively.

Originality/value

In view of the large load transfer, the strong coupling characteristics of tire , the suspension and the steering system during coach corning, the vehicle reference steering characteristics is defined considering vehicle nonlinear characteristics and the feedforward term of torque vectoring control at different steering angles and speeds is designed. Meanwhile, in order to improve the robustness of controller, an anti-integral saturation sliding mode variable structure control algorithm is proposed as the feedback term of torque vectoring control.

Details

Assembly Automation, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 12 October 2021

Mekhala Kaluarachchi, K.G.A.S. Waidyasekara and Raufdeen Rameezdeen

Construction activities generate noise that is harmful to workers and the neighbouring community. Engineering control methods are often used for its control which are…

Abstract

Purpose

Construction activities generate noise that is harmful to workers and the neighbouring community. Engineering control methods are often used for its control which are expensive and limited in effectiveness. This study aims to investigate factors that affect employee behaviour and how it could be used by construction companies to manage noise pollution on sites.

Design/methodology/approach

Norm Activation Model (NAM) is used to investigate the relationship between attitudes and behaviour of site-based employees using a questionnaire survey administered in Colombo, Sri Lanka. The responses were analysed using structural equation modelling to discern behavioural patterns and how it differs between managers and workers.

Findings

The results showed that behaviour of site employees could be influenced when they are aware of the consequences of noise pollution and take responsibility for its control. Personal norm of an employee and company's environmental behaviour are found to influence the behaviour in a positive manner.

Practical implications

Construction companies should focus more on how to harness their employee's behaviour in order to reduce noise pollution on sites. Employees should be made aware of consequences of noise pollution and feel responsible for their actions through training, awareness campaigns, signage and so on.

Originality/value

This study contributes to the literature by building a theoretical model of employee noise control behaviour in construction organizations and empirically testing it among managers and workers. It compares the differences between these two groups which enhances one’s understanding of behavioural control methods when applied in a construction project setting. The study also evaluates the effects of company's environmental behaviour on employee behaviour.

Details

Built Environment Project and Asset Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2044-124X

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Article
Publication date: 25 October 2021

Yang Yuan and Haibin Duan

The purpose of this paper is to develop a novel active disturbance rejection attitude controller for quadrotors and propose a controller parameters identification approach…

Abstract

Purpose

The purpose of this paper is to develop a novel active disturbance rejection attitude controller for quadrotors and propose a controller parameters identification approach to obtain better control results.

Design/methodology/approach

Aiming at the problem that quadrotor is susceptible to disturbance in outdoor flight, the improved active disturbance rejection control (IADRC) is applied to design attitude controller. To overcome the difficulty that adjusting the parameters of IADRC controller manually is complex, paired coevolution pigeon-inspired optimization (PCPIO) algorithm is used to optimize the control parameters.

Findings

The IADRC, where nonlinear state error feedback control law is replaced by non-singular fast terminal sliding mode control law and a third-order tracking differentiator is designed for second derivative of the state, has higher control accuracy and better robustness than ADRC. The improved PIO algorithm based on evolutionary mechanism, named PCPIO, is proposed. The optimal parameters of ADRC controller are found by PCPIO with the optimization criterion of integral of time-weighted absolute value of the error. The effectiveness of the proposed method is verified by a series of simulation experiments.

Practical implications

IADRC can improve the accuracy of attitude control of quadrotor and resist external interference more effectively. The proposed PCPIO algorithm can be easily applied to practice and can help the design of the quadrotor control system.

Originality/value

An improved active disturbance rejection controller is designed for quadrotor attitude control, and a hybrid model of PIO and evolution mechanism is proposed for parameters identification of the controller.

Details

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

Keywords

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