Long Chen, Zheyu Zhang, Ni An, Xin Wen and Tong Ben
The purpose of this study is to model the global dynamic hysteresis properties with an improved Jiles–Atherton (J-A) model through a unified set of parameters.
Abstract
Purpose
The purpose of this study is to model the global dynamic hysteresis properties with an improved Jiles–Atherton (J-A) model through a unified set of parameters.
Design/methodology/approach
First, the waveform scaling parameters β, λk and λc are used to improve the calculation accuracy of hysteresis loops at low magnetic flux density. Second, the Riemann–Liouville (R-L) type fractional derivatives technique is applied to modified static inverse J-A model to compute the dynamic magnetic field considering the skin effect in wideband frequency magnetization conditions.
Findings
The proposed model is identified and verified by modeling the hysteresis loops whose maximum magnetic flux densities vary from 0.3 to 1.4 T up to 800 Hz using B30P105 electrical steel. Compared with the conventional J-A model, the global simulation ability of the proposed dynamic model is much improved.
Originality/value
Accurate modeling of the hysteresis properties of electrical steels is essential for analyzing the loss behavior of electrical equipment in finite element analysis (FEA). Nevertheless, the existing inverse Jiles–Atherton (J-A) model can only guarantee the simulation accuracy with higher magnetic flux densities, which cannot guarantee the analysis requirements of considering both low magnetic flux density and high magnetic flux density in FEA. This paper modifies the dynamic J-A model by introducing waveform scaling parameters and the R-L fractional derivative to improve the hysteresis loops’ simulation accuracy from low to high magnetic flux densities with the same set of parameters in a wide frequency range.
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Er‐shun Pan, Yao Jin and Ying Wang
The purpose of this paper is to develop an extensive economic production quantity (EPQ) model on the basis of previous research. Considering an imperfect three‐state production…
Abstract
Purpose
The purpose of this paper is to develop an extensive economic production quantity (EPQ) model on the basis of previous research. Considering an imperfect three‐state production process, this paper makes contributions to an integrated model combining conceptions of quality loss and design of control chart based on EPQ model. The objective is to minimize the total production cost with the determination of EPQ and design parameters of control chart subjected to quality loss and other process costs.
Design/methodology/approach
In this paper, imperfect process is defined as a three‐state process, and the quality cost corresponding to each state contributes to the eventual total expected cost formulation. Control chart is used to monitor the shift from the target value within whole process and its control limits are set to be related to the quality cost.
Findings
The proposed integrated model conforms more closely to the real situation of production process considering the process shift as a random variable.
Practical implications
Numerical computation and sensitivity analysis through a case study are presented to demonstrate the applications of the model.
Originality/value
Few research efforts investigate an integrated model considering EPQ, control chart and quality loss simultaneously. In particular, compared with the former researches, the process shift, due to which the quality cost incurs, is considered as a random variable in this paper.
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Bambang Rilanto Trilaksono, Ryan Triadhitama, Widyawardana Adiprawita, Artiko Wibowo and Anavatti Sreenatha
The purpose of this paper is to present the development of hardware‐in‐the‐loop simulation (HILS) for visual target tracking of an octorotor unmanned aerial vehicle (UAV) with…
Abstract
Purpose
The purpose of this paper is to present the development of hardware‐in‐the‐loop simulation (HILS) for visual target tracking of an octorotor unmanned aerial vehicle (UAV) with onboard computer vision.
Design/methodology/approach
HILS for visual target tracking of an octorotor UAV is developed by integrating real embedded computer vision hardware and camera to software simulation of the UAV dynamics, flight control and navigation systems run on Simulink. Visualization of the visual target tracking is developed using FlightGear. The computer vision system is used to recognize and track a moving target using feature correlation between captured scene images and object images stored in the database. Features of the captured images are extracted using speed‐up robust feature (SURF) algorithm, and subsequently matched with features extracted from object image using fast library for approximate nearest neighbor (FLANN) algorithm. Kalman filter is applied to predict the position of the moving target on image plane. The integrated HILS environment is developed to allow real‐time testing and evaluation of onboard embedded computer vision for UAV's visual target tracking.
Findings
Utilization of HILS is found to be useful in evaluating functionality and performance of the real machine vision software and hardware prior to its operation in a flight test. Integrating computer vision with UAV enables the construction of an unmanned system with the capability of tracking a moving object.
Practical implications
HILS for visual target tracking of UAV described in this paper could be applied in practice to minimize trial and error in various parameters tuning of the machine vision algorithm as well as of the autopilot and navigation system. It also could reduce development costs, in addition to reducing the risk of crashing the UAV in a flight test.
Originality/value
A HILS integrated environment for octorotor UAV's visual target tracking for real‐time testing and evaluation of onboard computer vision is proposed. Another contribution involves implementation of SURF, FLANN, and Kalman filter algorithms on an onboard embedded PC and its integration with navigation and flight control systems which enables the UAV to track a moving object.
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Thu Trang Thi Ngo, Hong Quan Nguyen, Timothy Gorman, Quang Ngo Xuan, Phuong Lan Thi Ngo and Ann Vanreusel
Drought and salinity intrusion aggravated by climate change threaten agricultural livelihoods in Viet Nan's Mekong Delta. In response, authorities have built water management…
Abstract
Purpose
Drought and salinity intrusion aggravated by climate change threaten agricultural livelihoods in Viet Nan's Mekong Delta. In response, authorities have built water management infrastructure for irrigation and salinity protection. This study assessed the impact of one such project, the Ba Lai dam in Ben Tre province, on the livelihoods of aquaculture farmers.
Design/methodology/approach
This study uses the Sustainable Livelihoods Framework to assess the impact of the Ba Lai dam on the livelihood capitals of 18 farming households in four communes, located both upstream and downstream of the dam.
Findings
The authors find that, apart from some positive effects, the dam has also brought negative environmental consequences, such as increased water pollution. The authors also find that farmers have responded to the changes by adapting their livelihood practices.
Research limitations/implications
The samples were relatively small, encompassing four communes in Ben Tre province. On the other hand, this case study is instructive to the many ongoing infrastructure projects in the Vietnamese Mekong Delta.
Social implications
The project have caused an increase in water-related social conflict.
Originality/value
The case of the Ba Lai dam provides a cautionary example for infrastructure-based water management plans, both in Viet Nam and more broadly. The study suggests the need to strengthen community participation and prioritize impacts of farmers' capital assets when constructing water management infrastructure for climate change adaptation.
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This paper aims to examine the impact of government ownership on the cost of debt and firm valuation in listed Vietnamese companies for the period 2007 to 2016.
Abstract
Purpose
This paper aims to examine the impact of government ownership on the cost of debt and firm valuation in listed Vietnamese companies for the period 2007 to 2016.
Design/methodology/approach
The authors use both the generalised methods of the moment (GMM) and the ordinary least squares (OLS) regressions to analyse a panel data spanning over the period 2007 to 2016 in the markets of Vietnam. Further, the instrumental variable is used in the paper.
Findings
The authors find that firms with relative higher government stockholdings or state-owned companies where the government owns 50 per cent or more of shares outstanding enjoy a lower cost of debt compared to the other firms. Consequently, these firms have higher firm valuation and profitability. The results are robust for both the GMM and the OLS regressions. Further, firms that no longer retain government ownership have a higher cost of debt than the other firms. The results of the paper imply the importance of political connections in businesses in the market of Vietnam.
Originality/value
This paper connects the relationship between government ownership and the cost of debt with the relationship between government ownership and firm valuation. The paper tests the relationship between the cost of debt and government ownership using both OLS and GMM specifications and the results are robust for both approaches. The manuscript uses an instrumental variable to show that government ownership has a positive impact on higher firm performance through reducing cost of debt. Further, this paper addresses the possible issue of endogeneity.
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Salima Ben Ezzeddine and Kamel Naoui
The aim of this chapter is to assess the real exchange rate misalignments. A smooth transition autoregressive model (STAR) is used for Tunisian exchange market. This model allows…
Abstract
The aim of this chapter is to assess the real exchange rate misalignments. A smooth transition autoregressive model (STAR) is used for Tunisian exchange market. This model allows us to see whether these differences are temporary or persistent over the period 1975–2012. We start by defining the exchange rate’s fundamental determinants to provide the equilibrium exchange rate value. Then, we study the observed exchange rate adjustment toward its equilibrium level. Vector autoregressive model and vector error correction model are applied to characterize the joint dynamics of variables in the long run. The results indicate a long-run relationship between variables. In order to consider the nonlinearity for better results, we will move to nonlinear smooth transition model. We found there is a high degree of exchange rate misalignment. We recognized that this difference decreases in the long run and disappears at the end.
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The purpose of this paper is to assess the current state of consumer education in the context of responsible gambling in Macao and to suggest ways in which Macao could enhance its…
Abstract
Purpose
The purpose of this paper is to assess the current state of consumer education in the context of responsible gambling in Macao and to suggest ways in which Macao could enhance its consumer education efforts to meet its challenges with regard to responsible gambling.
Design/methodology/approach
Exploratory and interpretative approaches have been adopted to suggest why and how Macao should strengthen responsible gambling education. The methodology involved extensive review of relevant academic research, government documents and reports related to Macao's responsible gambling initiatives.
Findings
Effective long-term responsible gambling education is needed in Macao to further people's understanding of gambling and gambler's fallacy. The government should take leadership in influencing all stakeholders toward effective initiatives and behaviors related to responsible gambling education.
Originality/value
Although research on responsible gambling education is still in its infancy, its importance in reducing common misconceptions about gambling has already been established. This study contributes to strengthen Macao's responsible gambling practices by proposing several changes needed to provide desired outcomes through consumer education.