Huaishu Li, Yanhui Lai, Wu Qiang and Xiang Dong
In order to research the law of the low‐frequency power oscillation which often exists in the synchronous generator rectification system, the purpose of this paper is to study…
Abstract
Purpose
In order to research the law of the low‐frequency power oscillation which often exists in the synchronous generator rectification system, the purpose of this paper is to study theoretical analysis and numerical calculation on the static stability of the system.
Design/methodology/approach
Different from the common three‐phase synchronous generator operating in large power networks, the stability of synchronous generator rectification systems is much more difficult to analyze because of its nonlinear loads. Some papers have analyzed the stability of the synchronous generator rectification system and presented different parameter conditions of system stability, but since factors that influence the system stability are complex, the essence of this kind of oscillation is not completely known yet. By considering rectification systems as an equivalent to DC circuits, the correct circuit model which is necessary to analyze the rectification systemic stability is set up, the changing law and relationship of various parameters under mini‐disturbances is analyzed, a linear differential equation about the DC‐side average current is derived, the stability of the synchronous generator rectification system is analyzed and deduced by using Hull criterion, all parameters influencing system stability are calculated and analyzed, and their ranges for a stable rectification system are given. Also, the reason why and how the parameters affect system stability is explained.
Findings
The operational stability of synchronous generator rectification systems is completely and correctly recognized.
Practical implications
The paper has a reference value for the design and safe operation of synchronous generator rectification systems.
Originality/value
The paper puts forward system stability criterion and gives a rational physical explanation about system stability.
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Huaishu Li, Lizhong Song and Yanhui Lai
In order to improve performance robustness of control systems, the discrete variable structure control (VSC) design for uncertain systems and its application to a ship autopilot…
Abstract
Purpose
In order to improve performance robustness of control systems, the discrete variable structure control (VSC) design for uncertain systems and its application to a ship autopilot are to be discussed in this paper.
Design/methodology/approach
Discrete‐time variable structure control (DVSC) becomes worth investigating and various DVSC methods have been suggested by many papers. The approach that used the reaching law for controller design can describe how the switching function decreases toward zero and easier to obtain the control law, but this conventional method has some defects not to be ignored. First, due to the influence of the conventional discrete reaching law itself, the system trajectory oscillates in a neighborhood of the origin rather than converges to the origin. Second, this method requires that the uncertainty bound is known as a premise to assure robustness, so creates an over‐conservative controller and enlarges chattering.
Findings
It can be shown that the estimation error dynamics can be decoupled from sliding surface dynamics using the proposed scheme. Robust stability of the closed‐loop system can be ensured in the presence of uncertainties with bounded changing rate. No chattering occurs.
Practical implications
To supply useful references to controller design.
Originality/value
A new approach in the design of discrete VSC based on the reaching law approach is presented, a new discrete reaching law, which is stable at the origin, is proposed, and an algorithm for uncertainty estimation is developed in this paper. The proposed algorithm is applied to the control of a ship autopilot servo system. Simulation results show that the controller designed here can track a desired course well and exhibits very good performance robustness.
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Yanhui Lai, Xiaofeng Zhang and Lizhong Song
The purpose of this paper is to overcome the shortcoming that discrete variable structure control (VSC) system trajectory oscillates in a neighborhood of the origin.
Abstract
Purpose
The purpose of this paper is to overcome the shortcoming that discrete variable structure control (VSC) system trajectory oscillates in a neighborhood of the origin.
Design/methodology/approach
Among all the proposed reaching laws, W. Gao's theory is most perfect. It makes great progress in revealing the motion mechanism of discrete‐time VSC systems. However, it has an obvious defect, i.e. the system trajectory oscillates in a neighborhood of the origin rather than converges to the origin. So, a new reaching law named variable rate reaching law to which the stability at the origin can be expected is proposed. The special feature of this new reaching law is that it is directly proportional to the norm of the state vector and can result in a sector‐shaped switching region. On the basis of analyzing the characteristic of the variable rate and the conventional reaching laws, a new combined control algorithm that discards the shortcomings of the two reaching laws and carries on their merits is formed, so satisfactory control performance can be achieved.
Findings
A new combined reaching law control algorithm, which uses the exponential rate reaching law in the reaching mode and in the front phase of the sliding mode, and uses the variable rate reaching law in the back phase of the sliding mode and in the steady‐state mode, is formed.
Practical implications
The paper is a very useful reference for control system designers.
Originality/value
The new control strategy is applied to the controller design for a brushless DC servomotor and good control performance is obtained.
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This study aims to selects a teacher training program located in China’s rural area and focus on its preservice teachers’ attitudes towards inclusive education in China and their…
Abstract
Purpose
This study aims to selects a teacher training program located in China’s rural area and focus on its preservice teachers’ attitudes towards inclusive education in China and their expectations of teacher training programs.
Design/methodology/approach
The selected teacher training program is in School of Education of a comprehensive university, located in a small town in Northeast China. Five preservice teachers in the Department of Teacher Education were interviewed. The interviewees were randomly selected among those who have already gained at least 60 credits of coursework prior to the interview. Each interview lasted for approximately 0.5 h. Interview notes were summarized and coded using Braun and Clarke’s (2006) six-step approach. In addition to interview data, other data sources were used, such as classroom observation and review of curriculum and program requirement.
Findings
Although the selected teacher preparation program started offering some selective special education courses to preservice teachers, there are limited number of offerings and a lack of field placement in inclusive settings, and stereotypical opinions towards disabilities still exist as a roadblock for choosing special education teacher profession.
Research limitations/implications
The current study only focuses on one rural teacher training institution and report preservice teachers’ opinions toward teacher education curriculum, factors that lead to their decision in the teacher education major and their vision towards inclusion in China. Recommendations are provided to increase public awareness of disability, and create more field based experience in inclusive settings for preservice teachers. However, the result may not be generalized to reflect preservice teachers of teacher training institutions located in developed areas where there are rich opportunities for field experience in inclusive setting or special education programs, and who offer more extensive special education courses.
Practical implications
It is recommended that teacher preparation program modify curriculum and offer more special education courses, as well as develop connections with local special education schools and inclusive programs, thus creating more field based opportunities for preservice teachers to work with children with disabilities.
Originality/value
There are limited studies on rural preservice teachers’ attitudes towards being a special education teacher and how the teacher training programs prepare them to become a special education teacher. The current study fills the gap and conduct an interview study of preservice teachers’ from a rural teacher training programs perceptions of China’s special education, how they choose the program of study that prepare them to become a special education teacher, and their rating of the teacher preparation program.
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Yanhui Mao, Shuangyang Guo, Mei Xie, Junkai Yu, Xuyuan Deng, Yingchao Li, Yuxi Zhai and Feng Kong
This paper aims to examine the day-to-day within-person associations between employees' flow experience and organizational identification within the rarely studied context of…
Abstract
Purpose
This paper aims to examine the day-to-day within-person associations between employees' flow experience and organizational identification within the rarely studied context of construction engineering project organizations.
Design/methodology/approach
In this daily diary design, the authors surveyed 204 (Mage = 28.3, SD = 5.69) employees of a state-owned construction engineering project organization in southwest China via the online questionnaires comprising flow and organizational identification scales once daily on each workday for three consecutive weeks, which yielded 3,060 data entries. The authors then tested the temporal directionality between flow and organizational identification with multilevel time-series cross-lagged path analysis using Mplus 8.3.
Findings
Daily flow experience was linked positively with same-day organizational identification. Importantly, flow experience on the previous day predicted organizational identification on a subsequent day, but not vice versa.
Practical implications
This study suggests that construction engineering project managers should implement interventions fostering the employees' flow experience to promote organizational identification, with important implications for organizations aiming at flourishing workforces by facilitating organizational identification through implementing flow strategies.
Originality/value
There is a dearth of diary studies on flow and organizational identification specific to construction engineering project employees. The authors’ findings provide concrete evidence of the fluctuant nature of daily flow experience and organizational identification as well as their dynamic predictive pathway relationship.
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Yanhui Chen, Bin Liu and Tianzi Wang
This paper applied grey wave forecasting in a decomposition–ensemble forecasting method for modelling the complex and non-linear features in time series data. This application…
Abstract
Purpose
This paper applied grey wave forecasting in a decomposition–ensemble forecasting method for modelling the complex and non-linear features in time series data. This application aims to test the advantages of grey wave forecasting method in predicting time series with periodic fluctuations.
Design/methodology/approach
The decomposition–ensemble method combines empirical mode decomposition (EMD), component reconstruction technology and grey wave forecasting. More specifically, EMD is used to decompose time series data into different intrinsic mode function (IMF) components in the first step. Permutation entropy and the average of each IMF are checked for component reconstruction. Then the grey wave forecasting model or ARMA is used to predict each IMF according to the characters of each IMF.
Findings
In the empirical analysis, the China container freight index (CCFI) is applied in checking prediction performance. Using two different time periods, the results show that the proposed method performs better than random walk and ARMA in multi-step-ahead prediction.
Originality/value
The decomposition–ensemble method based on EMD and grey wave forecasting model expands the application area of the grey system theory and graphic forecasting method. Grey wave forecasting performs better for data set with periodic fluctuations. Forecasting CCFI assists practitioners in the shipping industry in decision-making.
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This article discusses the reasons and discourses adopted by the Hong Kong Special Administrative Region Government (Hong Kong SAR Government), with Mr Tung Chee Hwa as the Chief…
Abstract
This article discusses the reasons and discourses adopted by the Hong Kong Special Administrative Region Government (Hong Kong SAR Government), with Mr Tung Chee Hwa as the Chief Executive, in preparing young people to become more mature and responsible. In the Hong Kong context this means they should be willing to fulfil community obligations and opt for consultation rather than confrontation should individual or community rights be sought. Confucianism, named after Confucius (551‐479 BCE), has been and still is a vast and complicated system of philosophies, morals, rituals, and ideas, which for well over 2,000 years has informed and inspired the thinking and practice of countless people in Chinese societies and Asian countries in all important areas, including the economy and the polity (Tu, 1998a; Berthrong & Berthrong, 2000; Yao, 2002). Put simply, the goal of Confucian life is to create a peaceful world, with its ethical emphasis placed on the cultivation of the self and the promotion of harmonious and respectful relations with other people in different spheres of human activities.
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Xiaochuan Jiang, Jianfeng Yang, Xiyan Wang and Yanhui Hou
To enhance the understanding of the antecedents of students' career adaptability, this study employs the crossover model to explore the potential transfer of career adaptability…
Abstract
Purpose
To enhance the understanding of the antecedents of students' career adaptability, this study employs the crossover model to explore the potential transfer of career adaptability from headteachers to students and the underlying mechanisms involved.
Design/methodology/approach
This study examined the proposed moderated mediation model using matched survey data collected from 37 headteachers and 1,598 students in Chinese higher vocational colleges.
Findings
Headteachers’ career adaptability is positively related to students’ career adaptability via students’ psychological capital. An increased frequency of headteacher–student interactions strengthened the indirect relationship between headteachers' career adaptability and students' career adaptability.
Originality/value
The findings suggest that, under certain conditions, headteachers’ career adaptability could be transferred to students via students’ psychological capital.
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Yanhui Sun, Junkang Guo, Jun Hong and Guanghui Liu
This paper aims to develop a theoretical method to analyze the rotation accuracy of rotating machinery with multi-support structures. The method effectively considers the…
Abstract
Purpose
This paper aims to develop a theoretical method to analyze the rotation accuracy of rotating machinery with multi-support structures. The method effectively considers the geometric errors and assembly deformation of parts.
Design/methodology/approach
A method composed of matrix and FEA methods is proposed to do the analysis. The deviation propagation analysis results and external loads are set as boundary conditions of the model which is built with Timoshenko beam elements to calculate the spatial pose of the rotor. The calculation is performed repeatedly as the rotation angle increased to get the rotation trajectories of concerned nodes, and further evaluation is done to get the rotation accuracy. Additionally, to get more reliable results, the bearing motion errors and stiffness are analyzed by a static model considering manufacturing errors of parts.
Findings
The feasibility of the proposed method is verified through a case study of a high-precision spindle. The method reasonably predicts the rotation accuracy of the spindle.
Originality/value
For rotating machinery with multi-support structures, the paper proposes a modeling method to predict the rotation accuracy, simultaneously considering geometric errors and assembly deformation of parts. This would improve the accuracy of tolerance analysis.
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Himanshu Gupta and Mukesh Kumar Barua
Innovation is a prerequisite for economic and technological growth of any organization. Identifying enablers of innovation can help managers accelerate the process of economic…
Abstract
Purpose
Innovation is a prerequisite for economic and technological growth of any organization. Identifying enablers of innovation can help managers accelerate the process of economic growth. The purpose of this paper is to identify the prominent enablers of innovation in small and medium enterprises (SMEs) that can help overhauling organizations and benefit them economically.
Design/methodology/approach
A comprehensive literature review and expert’s opinions have been applied to identify enablers of innovation. A case of automotive component supplier is considered for conducting the research. A coalescence of Grey and DEMATEL methodologies has been incorporated to first rank the enablers of innovation based on their importance and then identify the causal relationship among these enablers by characterizing enablers into causal and effect groups.
Findings
A few important enablers, namely, entrepreneur traits, knowledge management, resources for innovation, and linkage capabilities, have been identified as prominent enablers for successful innovation in SMEs.
Practical implications
This paper identifies enablers of innovation in SMEs and the causal relationship between these enablers. The identified enablers and the causal relationship between these enablers will help managers of small organizations in selecting the enablers that need to be focused on, which, in turn, can drive other enablers of innovation, thus saving time and resources of the organizations.
Originality/value
This paper uses a novel Grey–DEMATEL methodology to identify the causal relationship among enablers and also contributes to the literature on innovation by identifying enablers of innovation in SMEs.