Y. Choua, Y. Le Bihan and L. Pichon
The aim of this paper is to calculate the impedance of a loop antenna, etched on a dielectric substrate, over a wide frequency band using finite element method (FEM).
Abstract
Purpose
The aim of this paper is to calculate the impedance of a loop antenna, etched on a dielectric substrate, over a wide frequency band using finite element method (FEM).
Design/methodology/approach
The electromagnetic analysis of the global structure is performed with a full wave finite element formulation. In this work, two methods for the calculation of the impedance of the antenna are presented: receiving and transmitting mode. The results obtained are compared with boundary element method (BEM).
Findings
The paper finds that from the FEM analysis an equivalent circuit of a rectenna was obtained over a wide frequency band. A good agreement was obtained with a BEM approach in the case of an air‐like substrate. A dielectric substrate was considered. Such a configuration is more difficult to deal with BEM and makes the FEM attractive.
Practical implications
The equivalent circuit allows a global circuit simulation of the whole rectenna (antenna, rectifying diodes and load). This simulation can be achieved using spice simulator for example.
Originality/value
This paper shows the potentiality of the FEM to simulate an antenna over a broad band frequency. Two methods for the calculation of the impedance of the antenna are presented. It is addressed to R&D designers in the microwave area.
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Polyanna Mara Pereira, Felipe Campelo, Takuya Mori, Hajime Igarashi and Ricardo Adriano
This paper aims to present a SPICE model to represent antennas in receiving mode. The model can be used to evaluate the performance of the antenna when it is coupled to several…
Abstract
Purpose
This paper aims to present a SPICE model to represent antennas in receiving mode. The model can be used to evaluate the performance of the antenna when it is coupled to several different nonlinear electric circuits. The proposed methodology is particularly suitable for rectenna applications, as it allows the analysis of different configurations for a rectenna more efficiently than using full-wave analysis simulators coupled directly to each rectifier circuit.
Design/methodology/approach
The model presented uses reciprocity theory to calculate the ideal voltage source of the Thevenin-equivalent circuit for an antenna. Vector fitting is then used to approximate the model to rational functions that can be converted to Resistor, Inductor and Capacitor circuits. Additional components are added to the circuit to prevent numerical instability.
Findings
Two rectennas are used to illustrate the performance of the proposed model, one based on a 2.45-GHz rectangular patch antenna and another based on a planar spiral antenna. The second antenna has impedance with positive and negative real parts along the frequency range, which could lead to numerical instabilities. The proposed method is shown to be stable while working with these negative resistance values, which may appear during circuit parameterization.
Research limitations/implications
The equivalent SPICE circuit model for the antenna makes it easy to simulate nonlinear circuits connected to the antenna and perform transient analyses. The computational cost of antenna analysis is reduced, being more computationally efficient than methods that involve full-wave simulation. This characteristic makes it an interesting approach for working with rectennas, or any application where the time constant of the circuit is much longer than the period of the incident wave.
Originality/value
For most antenna applications, the numerical stability of the circuit can be achieved using passive enforcement. However, depending on the phase response of the antenna, the impedance that represents its far-field characteristic may present a negative real part, in which case, passive enforcement will fail. In this paper, the problem of numerical instability is solved by introducing an offset resistance and a current-controlled voltage source to the model.
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In the literature, while designing broadband matching networks, transducer power gain (TPG) is used to measure the transferred power. Generally, in TPG expressions, load and…
Abstract
Purpose
In the literature, while designing broadband matching networks, transducer power gain (TPG) is used to measure the transferred power. Generally, in TPG expressions, load and back-end impedances of the matching network are used. This study aims to derive a new quality factor-based TPG expression.
Design/methodology/approach
In deriving the new expression, narrowband L type-matching network design approach is used and the new expression in terms of back-end quality factor, load quality factor and output port quality factor is obtained. Then, a broadband-matching network design approach using the derived TPG expression is proposed.
Findings
Two broadband double-matching networks are designed by using the proposed design approach using the derived TPG expression. Performances of the designed-matching networks are compared with the performances of the matching networks designed by means of simplified real frequency technique which is a well-known technique in the literature, and it is shown that they are nearly the same.
Originality/value
In broadband-matching problems, generally an impedance-based TPG expression is used, and it must be satisfied by the designed broadband-matching networks. But, in the literature, there is no quality factor-based TPG expression that can be used in broadband-matching problems. So, this gap in the literature has been filled by this paper.
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Reza Mirzahosseini, Ahmad Darabi and Mohsen Assili
Consideration of leakage fluxes in the preliminary design stage of a machine is important for accurate determination of machine dimensions and prediction of performance…
Abstract
Purpose
Consideration of leakage fluxes in the preliminary design stage of a machine is important for accurate determination of machine dimensions and prediction of performance characteristics. This paper aims to obtain some equations for calculating the average air gap flux density, the flux density within the magnet and the air gap leakage flux factor.
Design/methodology/approach
A detailed magnetic equivalent circuit (MEC) is presented for a TORUS-type non-slotted axial flux permanent magnet (TORUS-NS AFPM) machine. In this MEC, the leakage flux occurring between two adjacent magnets and the leakage fluxes taking place between the magnet and rotor iron at the interpolar, inner and outer edges of the magnets are considered. According to the proposed MEC and by using flux division law, some equations are extracted. A three-dimensional finite element method (FEM) is used to evaluate the proposed analytical equations. The study machine is a 3.7 kW and 1,400 rpm TORUS-NS AFPM machine.
Findings
The air gap leakage flux factor, the average air gap flux density and the flux density within the magnet are calculated using the proposed equations and FEM. All the results of FEM confirm the excellent accuracy of the proposed analytical method.
Originality/value
The new equations presented in this paper can be applied for leakage flux evaluating purposes.
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Woan-lih Liang, Duc Nguyen Nguyen, Quynh-Nhu Tran and Quang-Thai Truong
This study aims to revisit the link between employee welfare and firm financial performance using a large sample. Besides, the study explores mechanisms behind the link and…
Abstract
Purpose
This study aims to revisit the link between employee welfare and firm financial performance using a large sample. Besides, the study explores mechanisms behind the link and heterogeneous effects of employee welfare on firm performance across firms and industries with different characteristics. These findings help partly explain mixed results in previous works.
Design/methodology/approach
This study utilized KLD database data from 2001 to 2015 to capture the firm-level employee welfare, then analyze the link between employee welfare and firm financial performance. The findings are further verified using clustered standard errors ordinary least squares (OLS) regression analysis along with robustness testing, which supports the validity of our conclusions.
Findings
The research result confirms a positive association between employee-friendly practices and firm performance indicated by Tobin's q. Regarding the mechanisms linking the two, the study shows that higher employee welfare is positively associated with firm productivity and innovation investment, while it is negatively related to the cost of finance. Further, consistent with agency and modern management theories, the effect of employee welfare on financial performance is more pronounced for human-intensive (i.e. R&D-based) firms and firms with better corporate governance.
Originality/value
This study contributes to the existing literature on the association between employee welfare and firm performance in several ways. First, using the index of employee welfare from KLD can alleviate inherent limitations in previous studies. Second, the authors provide and validate the possible mechanisms linking employee welfare and firm value. Third, the authors also extend the literature by providing new insights into the employee welfare–firm performance nexus through a contingency perspective.
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Abstract
Purpose
This paper aims to investigate the impact of environmental risk on corporate governance through market reaction to bank loan announcements.
Design/methodology/approach
Using the establishment of environment court in China as a quasi-natural experiment, this paper adopt the difference-in-differences approach based on listed firms during 2003–2013 to explore the impact of environment court on corporate governance.
Findings
This paper find that the environment court would weaken the cumulative abnormal return of loan announcements. Then, this paper confirm that the potential reason is that environment court worsens the interest conflict between majority and minority shareholders. Further, cross-sectional analysis suggests that bank’s supervision, market competition and analyst coverage can alleviate the impact of environment court on corporate governance.
Practical implications
Environment courts intensify firms’ internal interest disputes, thus causing the decrease of corporate governance, which can be observed through the effect of bank loan announcements.
Social implications
This paper provide reference for environmental policy formulation and implementation, firms’ decision-makings and improving the banking regulatory system.
Originality/value
This paper makes a contribution to the studies about the impact of environment court on firms’ decision-making and investors’ reaction, the impact of external factors on corporate governance and bank loan announcements effect.
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Brett Duarte, Douglas Montgomery, John Fowler and John Konopka
The purpose of this paper is to provide Lean Six Sigma deployment champions with a structured approach to identify and prioritize parts of their business that are conducive to the…
Abstract
Purpose
The purpose of this paper is to provide Lean Six Sigma deployment champions with a structured approach to identify and prioritize parts of their business that are conducive to the Lean Six Sigma methodology.
Design/methodology/approach
A five‐step approach to Lean Six Sigma project identification is presented in this paper. The approach utilizes a clustering technique to group similar processes based on seven process characteristics. The clusters formed are then evaluated and prioritized for their compatibility to Lean Six Sigma.
Findings
The clustering approach can be applied to any industry segment, including non‐manufacturing, healthcare and financial‐based organizations. A case study is presented in this paper in which the approach is applied to an IT based company. A total of 30 percent of the business processes were found to be Lean Six Sigma conducive.
Research limitations/implications
The current model does not have provision to consider the current performance of a process as an evaluation criterion. This requires the deployment champion to use the model in conjunction with a Balanced Scorecard. Future research will address this limitation.
Originality/value
There is a general lack of a mathematical approach to enable Lean Six Sigma practitioners to identify parts of their business that are conducive to the methodology. This research attempts to bridge this gap in the literature by using an unsupervised learning approach, using a clustering algorithm, to group processes based on seven process characteristics. The cluster evaluation helps the deployment champion identify key areas within the business to focus an LSS deployment.
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This purpose of this paper is to evaluate Millennials’ intention to use service mobile apps and assess gender as a moderator.
Abstract
Purpose
This purpose of this paper is to evaluate Millennials’ intention to use service mobile apps and assess gender as a moderator.
Design/methodology/approach
An extended technology acceptance model framework that includes information quality and self-efficacy guides this research. PLS-SEM is used to evaluate the data and test the hypotheses.
Findings
The study reveals that information quality, self-efficacy, perceived ease of use and usefulness, and attitude influence Millennials’ intentions to use service mobile apps. Additionally, gender is found to partially moderate the results.
Practical implications
Service companies that rely on mobile apps to deliver services ought to consider the disparities among the Millennial generation, increasing the likelihood that Millennial customers will adopt service mobile apps and that they receive acceptable customer experiences.
Originality/value
This paper examines the factors influencing adoption and use of service mobile apps among Millennials and examines gender as a moderator. Additionally, guidelines for service mobile app design are included.
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Mahdi Salehi and Ali Hassanzadeh
This study aims to investigate the effect of the dynamics and potential of the board of directors on investment efficiency and the comparability of financial information in…
Abstract
Purpose
This study aims to investigate the effect of the dynamics and potential of the board of directors on investment efficiency and the comparability of financial information in companies listed on the Tehran Stock Exchange.
Design/methodology/approach
The number of observations for this study includes 1,218 observations from companies listed on the Tehran Stock Exchange during 2014–2020. The authors used econometric statistical methods such as multiple linear regression, the Chow and Hausman test and the Kendall correlation coefficient using Eviews software to conduct the research. To measure the board’s effectiveness, two variables are used, including board dynamics and potential.
Findings
The results showed a positive and significant relationship between dynamics, board potential and investment efficiency. Also, no significant relationship was observed between the board dynamics and the comparability of financial information. Finally, a positive and significant relationship exists between the board’s potential and the comparability of financial information.
Originality/value
The importance of this research is the use of board proxies, including the dynamics and potential of the board. In addition, other variables of board characteristics, such as size, independence, ownership and gender, and the relationship between these variables with investment efficiency and comparability of financial information, have been examined in this study.
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Phung Anh Thu and Pham Quang Huy
This paper aims to explore the moderating role of state ownership variables on the relationship between market concentration (MC) and financial statement comparability (FSC) in…
Abstract
Purpose
This paper aims to explore the moderating role of state ownership variables on the relationship between market concentration (MC) and financial statement comparability (FSC) in Vietnam.
Design/methodology/approach
This study uses data from the financial statements of 475 nonfinancial listed companies for the period from 2010 to 2019. This study uses both the system generalized method of moments and fuzzy-set qualitative comparative analysis (fsQCA) to consider the correlation and causal–effect relationships of the variables in the model.
Findings
The results show that MC has a positive relationship with FSC, and MC tends to exert a stronger impact on FSC for firms with higher state ownership. In addition, this study suggests that some combinations help improve FSC. This study has important implications for investors, managers and especially state-owned organizations when market power becomes fierce.
Originality/value
This study contributes to the literature on the comparability of financial statements in the context of developing countries that have not fully adopted International Financial Reporting Standards. Furthermore, this study applies the fsQCA method to complement the linear regression method.