Dongqing Zhang, Xuanxi Ning and Xueni Liu
As the conventional multistep‐ahead prediction may be unsuitable in some cases, the purpose of this paper is to propose a novel method based on joint probability distributions…
Abstract
Purpose
As the conventional multistep‐ahead prediction may be unsuitable in some cases, the purpose of this paper is to propose a novel method based on joint probability distributions, which provides the most probable estimation for the predicted trajectory.
Design/methodology/approach
Many real‐time series can be modeled in hidden Markov models. In order to predict these time series online, sequential Monte Carlo (SMC) method is applied for joint multistep‐ahead prediction.
Findings
The data of monthly national air passengers in China are analyzed, and the experimental results demonstrate that the method proposed and the corresponding online algorithms are effective.
Research limitations/implications
In this paper, SMC method is applied for joint multistep‐ahead prediction. However, with the increasing of prediction step, the number of particles is increasing exponentially, which means that the prediction steps cannot be too large.
Practical implications
A very useful advice for researchers who study time‐series forecasts.
Originality/value
A novel method of multistep‐ahead prediction based on joint probability distribution is proposed and SMC method is applied to prediction time series online. This paper is aimed at those researchers who focus on time‐series forecasts.
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Sha Zhong, Mingzhi Yang, Bosen Qian, Lei Zhang, Dongqing He, Tongtong Lin and Fue-Sang Lien
This study aims to provide new insights into aerodynamic drag reduction for increasingly faster blunt-nosed trains, such as urban and freight trains. Specifically, this work…
Abstract
Purpose
This study aims to provide new insights into aerodynamic drag reduction for increasingly faster blunt-nosed trains, such as urban and freight trains. Specifically, this work investigates two distinctly different wake structures and associated aerodynamic drag of blunt-nosed trains.
Design/methodology/approach
Three typical cases of blunt-nosed trains with 1-, 2- and 3-m nose lengths are selected. The time-averaged and unsteady flow structures around the trains are analyzed using the improved delayed detached eddy simulation model and proper orthogonal decomposition method.
Findings
The simulation results indicate that for 2- and 3-m nose lengths, the flow separates at first and then reattaches to the slanted surface of the tail, with a pair of longitudinal vortices dominating the wake. In contrast, for the 1-m nose length case, the wake structure is characterized by complete separation, attributed to the larger curvature of the slanted tail surface. Consequently, the total time-averaged drag coefficient is reduced by 27.2% and 19.2% for the 1-m nose length case compared to the 2- and 3-m cases, respectively. Moreover, the predominant unsteady structures with Strouhal numbers St = 0.30 and St = 0.28 are detected in the near-wake of the 2- and 3-m nose length cases, respectively. These structures result from periodic vortex shedding at the lower slanted tail surface. In contrast, for the 1-m nose length case, the predominant unsteady structure with St = 0.19 is induced by the nearly periodic expansion and contraction of the upper bubbles.
Originality/value
Two distinctly different wake structures in blunt-nosed trains are identified. Unlike high-speed trains with longer, streamlined noses, for blunt-nosed trains, shorter nose lengths result in lower aerodynamic drag. Insights for reducing energy consumption in blunt-nosed trains are provided.
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Dongqing Yu, Junjun Chen and Masoumeh Kouhsari
This study aims to examine the roles of principal resilience (psychological, social and spiritual) and trust in colleagues in predicting the flourishing of school principals…
Abstract
Purpose
This study aims to examine the roles of principal resilience (psychological, social and spiritual) and trust in colleagues in predicting the flourishing of school principals, considering different career stages.
Design/methodology/approach
Utilising multigroup structural equation modelling and mediation analysis, data were collected from a sample of 1,274 school principals in China. The study investigates the direct impact of resilience on flourishing and the mediating role of trust in colleagues, with a focus on variations across different career stages.
Findings
The findings reveal that all aspects of a principal’s resilience significantly impact their flourishing, with trust serving as a partial mediator. Notably, the influence of spiritual resilience on flourishing is significant only for principals in the later stages of their careers.
Originality/value
This research contributes to the expanding body of literature on educational leadership by highlighting the importance of resilience and trust in fostering principal flourishing. The insights gained offer valuable knowledge for developing support strategies to enhance the flourishing experiences of school principals throughout their careers.
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Dongqing Zhu, Zhiying Zhang and Chunzhen Wang
It is generally believed that supervisors would deter employee unethical behavior. However, drawing from social exchange theory and the theory of moral disengagement, we posit…
Abstract
Purpose
It is generally believed that supervisors would deter employee unethical behavior. However, drawing from social exchange theory and the theory of moral disengagement, we posit that supervisors are more willing to tolerate employee unethical behavior through moral disengagement when the perpetrator is a high performing employee.
Design/methodology/approach
Study 1, which measured employee unethical behavior in a specific group of doctors through a time-lagged survey, and Study 2, which manipulated employee unethical behavior with a diverse sample by a vignette-based experiment, provided convergent support for our hypothesized 1st-stage moderated mediation model. Hierarchical regression, bootstrapping and ANOVA are used to test our hypotheses.
Findings
Although supervisors generally showed a low social acceptance of an employee who engaged in unethical behavior, they were more likely to socially accept the perpetrator through moral disengagement when the employee was a high rather than a low performer.
Practical implications
Given that supervisor's tolerance of employee unethical behavior may be more dangerous than employee unethical behavior itself, organizations should set up an ethics committee to handle top managers' unethical behavior and consider morality equally important with performance in management practice.
Originality/value
The current research extends research on the interpersonal consequences of employee unethical behavior, explains how moral disengagement promotes social acceptance and identifies the moderating effect of job performance in the process.
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Zhen Zhou, Dongqing Wang and Boyang Xu
The purpose of this paper is to explore a multi-innovation with forgetting factor-based EKF-SLAM (FMI-EKF-SLAM) algorithm to solve the error increasing problem, caused by the…
Abstract
Purpose
The purpose of this paper is to explore a multi-innovation with forgetting factor-based EKF-SLAM (FMI-EKF-SLAM) algorithm to solve the error increasing problem, caused by the Extended Kalman filtering (EKF) violating the local linear assumption in simultaneous localization and mapping (SLAM) for mobile robots because of strong nonlinearity.
Design/methodology/approach
A multi-innovation with forgetting factor-based EKF-SLAM (FMI-EKF-SLAM) algorithm is investigated. At each filtering step, the FMI-EKF-SLAM algorithm expands the single innovation at current step to an extended multi-innovation containing current and previous steps and introduces the forgetting factor to reduce the effect of old innovations.
Findings
The simulation results show that the explored FMI-EKF-SLAM method reduces the state estimation errors, obtains the ideal filtering effect and achieves higher accuracy in positioning and mapping.
Originality/value
The method proposed in this paper improves the positioning accuracy of SLAM and improves the EKF, so that the EKF has higher accuracy and wider application range.
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Ruyue Han, Xingmei Li, Zhong Shen and Dongqing Jia
The consideration of the substitution phenomenon in the project portfolio selection problem can improve the robustness of project portfolio selection and help enterprises better…
Abstract
Purpose
The consideration of the substitution phenomenon in the project portfolio selection problem can improve the robustness of project portfolio selection and help enterprises better achieve their strategic objectives. However, the existence of inter-project risk propagation will have a negative impact on project substitution. This paper proposes a new framework for project portfolio selection and constructs a risk propagation model based on strategic objectives to study the impact of risk propagation on substitution in the project portfolio.
Design/methodology/approach
The authors first construct a risk propagation model based on strategic objectives to describe the risk propagation between projects. Then the project substitution phenomenon based on risk propagation is put forward, and the calculation method of substitution loss is given. Finally, a robust project portfolio selection framework based on strategic objectives considering risk propagation is constructed.
Findings
The analysis of a case study demonstrates that (1) With the increase of risk intensity, the strategic loss of the same project portfolio increases linearly, and under the same risk intensity, the more projects in the portfolio, the stronger the robustness. (2) Considering risk propagation, the effect of project substitution is significantly weakened, and the strategic loss rate of the project portfolio is significantly increased compared with that of a direct attack.
Originality/value
This study is the first to take the project substitution into account in the project portfolio selection process. Moreover, the authors describe inter-project risk propagation and analyze the impact of risk propagation on the project substitution phenomenon. Finally, the authors extend the evaluation index of robustness. This paper puts forward a new way to solve the problem of project portfolio selection.
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Dongqing Yang, Jun Xiong and Rong Li
This paper aims to fabricate inclined thin-walled components using positional wire and arc additive manufacturing (WAAM) and investigate the heat transfer characteristics of…
Abstract
Purpose
This paper aims to fabricate inclined thin-walled components using positional wire and arc additive manufacturing (WAAM) and investigate the heat transfer characteristics of inclined thin-walled parts via finite element analysis method.
Design/methodology/approach
An inclined thin-walled part is fabricated in gas metal arc (GMA)-based additive manufacturing using a positional deposition approach in which the torch is set to be inclined with respect to the substrate surface. A three-dimensional finite element model is established to simulate the thermal process of the inclined component based on a general Goldak double ellipsoidal heat source and a combined heat dissipation model. Verification tests are performed based on thermal cycles of locations on the substrate and the molten pool size.
Findings
The simulated results are in agreement with experimental tests. It is shown that the dwell time between two adjacent layers greatly influences the number of the re-melting layers. The temperature distribution on both sides of the substrate is asymmetric, and the temperature peaks and temperature gradients of points in the same distance from the first deposition layer are different. Along the deposition path, the temperature distribution of the previous layer has a significant influence on the heat dissipation condition of the next layer.
Originality/value
The established finite element model is helpful to simulate and understand the heat transfer process of geometrical thin-walled components in WAAM.
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Qinxuan Gu, Dongqing Hu and Paul Hempel
Drawing on the motivated information processing in groups (MIP-G) model, the purpose of this paper is to explore the relationship between team reward interdependence and team…
Abstract
Purpose
Drawing on the motivated information processing in groups (MIP-G) model, the purpose of this paper is to explore the relationship between team reward interdependence and team performance, treating shared leadership as a mediator and team average job-based psychological ownership as a moderator.
Design/methodology/approach
Data were collected from a field sample of 72 knowledge-based work teams comprised of 466 team members and their team leaders. Data were analysed using hierarchical regression analysis and moderated path analysis.
Findings
Team reward interdependence was positively related to team performance through shared leadership. Team average job-based psychological ownership moderated both the relationship between team reward interdependence and shared leadership, and the indirect relationship between team reward interdependence and team performance.
Research limitations/implications
The shared leadership literature is extended by exploring the antecedents of shared leadership from the perspective of team incentives and by examining the moderating role of team average job-based psychological ownership.
Practical implications
Organizations and managers should pay attention to team pay system design and be aware of the importance of employees’ psychological ownership toward their jobs in promoting shared leadership in teams.
Originality/value
This study sheds light on the antecedents of shared leadership from motivated information processing perspective and examines antecedent boundary conditions through the moderating role of team average job-based psychological ownership.
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Dongxiao Niu, Ling Ji, Yongli Wang and Da Liu
The purpose of this paper is to improve the accuracy of short time load forecasting to ensure the economical and safe operation of power systems. The traditional neural network…
Abstract
Purpose
The purpose of this paper is to improve the accuracy of short time load forecasting to ensure the economical and safe operation of power systems. The traditional neural network applied in time series like load forecasting, easily plunges into local optimum and has a complicated learning process, leading to relatively slow calculating speed. On the basis of existing literature, the authors carried out studies in an effort to optimize a new recurrent neural network by wavelet analysis to solve the previous problems.
Design/methodology/approach
The main technique the authors applied is referred to as echo state network (ESN). Detailed information has been acquired by the authors using wavelet analysis. After obtaining more information from original time series, different reservoirs can be built for each subsequence. The proposed method is tested by using hourly electricity load data from a southern city in China. In addition, some traditional methods are also applied for the same task, as contrast.
Findings
The experiment has led the authors to believe that the optimized model is encouraging and performs better. Compared with standard ESN, BP network and SVM, the experimental results indicate that WS‐ESN improves the prediction accuracy and has less computing consumption.
Originality/value
The paper develops a new method for short time load forecasting. Wavelet decomposition is employed to pre‐process the original load data. The approximate part associated with low frequencies and several detailed parts associated with high frequencies components give expression to different information from original data. According to this, suitable ESN is chosen for each sub‐sequence, respectively. Therefore, the model combining the advantages of both ESN and wavelet analysis improves the result for short time load forecasting, and can be applied to other time series problem.
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The Library System of China and the Information System of China are the two systems of information organisations in China. This paper discusses the types of information agencies…
Abstract
The Library System of China and the Information System of China are the two systems of information organisations in China. This paper discusses the types of information agencies in each, focusing on structural characteristics, and governing regulations and especially on programmes and activities. Included in the discussion are such topics as publications, cooperative undertakings, new services and evaluation procedures.