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1 – 10 of 30Salma Benharref, Vincent Lanfranchi, Daniel Depernet, Tahar Hamiti and Sara Bazhar
The purpose of this paper is to propose a new method that allows to compare the magnetic pressures of different pulse width modulation (PWM) strategies in a fast and efficient way.
Abstract
Purpose
The purpose of this paper is to propose a new method that allows to compare the magnetic pressures of different pulse width modulation (PWM) strategies in a fast and efficient way.
Design/methodology/approach
The voltage harmonics are determined using the double Fourier integral. As for current harmonics and waveforms, a new generic model based on the Park transformation and a dq model of the machine was established taking saturation into consideration. The obtained analytical waveforms are then injected into a finite element software to compute magnetic pressures using nodal forces.
Findings
The overall proposed method allows to accelerate the calculations and the comparison of different PWM strategies and operating points as an analytical model is used to generate current waveforms.
Originality/value
While the analytical expressions of voltage harmonics are already provided in the literature for the space vector pulse width modulation, they had to be calculated for the discontinuous pulse width modulation. In this paper, the obtained expressions are provided. For current harmonics, different models based on a linear and a nonlinear model of the machine are presented in the referenced papers; however, these models are not generic and are limited to the second range of harmonics (two times the switching frequency). A new generic model is then established and used in this paper after being validated experimentally. And finally, the direct injection of analytical current waveforms in a finite element software to perform any magnetic computation is very efficient.
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The purpose of this paper is to present an up-to-date survey on the non-orthogonal multiple access (NOMA) technique with co-operative strategy, a fast-evolving fifth-generation…
Abstract
Purpose
The purpose of this paper is to present an up-to-date survey on the non-orthogonal multiple access (NOMA) technique with co-operative strategy, a fast-evolving fifth-generation (5 G) technology. NOMA is used for serving many mobile users, both in power and code domains. This paper considers the power-domain NOMA, which is now discussed as NOMA.
Design/methodology/approach
The first part of the paper discusses NOMA-based cooperative relay systems using different relay strategies over different channel models. In various research works, the analytical expressions of many performance metrics were derived, measured and simulated for better performance of the NOMA systems. In the second part, a brief introduction to diversity techniques is discussed. The multiple input and multiple output system merged with cooperative NOMA technology, and its future challenges were also presented in this part. In the third part, the paper surveys some new conceptions such as cognitive radio, index modulation multiple access, space-shift keying and reconfigurable intelligent surface that can be combined with NOMA systems for better performance.
Findings
The paper presents a brief survey of diverse research projects being carried out in the field of NOMA. The paper also surveyed two different relaying strategies that were implemented in cooperative NOMA over different channels and compared several performance parameters that were evaluated and derived in these implementations.
Originality/value
The paper provides a scope for recognizable future work and presents a brief idea of the new techniques that can be united with NOMA for better performance in wireless systems.
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Mouna Zerzeri, Intissar Moussa and Adel Khedher
The purpose of this paper aims to design a robust wind turbine emulator (WTE) based on a three-phase induction motor (3PIM).
Abstract
Purpose
The purpose of this paper aims to design a robust wind turbine emulator (WTE) based on a three-phase induction motor (3PIM).
Design/methodology/approach
The 3PIM is driven by a soft voltage source inverter (VSI) controlled by a specific space vector modulation. By adjusting the appropriate vector sequence selection, the desired VSI output voltage allows a real wind turbine speed emulation in the laboratory, taking into account the wind profile, static and dynamic behaviors and parametric variations for theoretical and then experimental analysis. A Mexican hat profile and a sinusoidal profile are therefore used as the wind speed system input to highlight the electrical, mechanical and electromagnetic system response.
Findings
The simulation results, based on relative error data, show that the proposed reactive power control method effectively estimates the flux and the rotor time constant, thus ensuring an accurate trajectory tracking of the wind speed for the wind emulation application.
Originality/value
The proposed architecture achieves its results through the use of mathematical theory and WTE topology combine with an online adaptive estimator and Lyapunov stability adaptation control methods. These approaches are particularly relevant for low-cost or low-power alternative current (AC) motor drives in the field of renewable energy emulation. It has the advantage of eliminating the need for expensive and unreliable position transducers, thereby increasing the emulator drive life. A comparative analysis was also carried out to highlight the online adaptive estimator fast response time and accuracy.
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Subhrapratim Nath, Jamuna Kanta Sing and Subir Kumar Sarkar
Advancement in optimization of VLSI circuits involves reduction in chip size from micrometer to nanometer level as well as fabrication of a billions of transistors in a single die…
Abstract
Purpose
Advancement in optimization of VLSI circuits involves reduction in chip size from micrometer to nanometer level as well as fabrication of a billions of transistors in a single die where global routing problem remains significant with a trade-off of power dissipation and interconnect delay. This paper aims to solve the increased complexity in VLSI chip by minimization of the wire length in VLSI circuits using a new approach based on nature-inspired meta-heuristic, invasive weed optimization (IWO). Further, this paper aims to achieve maximum circuit optimization using IWO hybridized with particle swarm optimization (PSO).
Design/methodology/approach
This paper projects the complexities of global routing process of VLSI circuit design in mapping it with a well-known NP-complete problem, the minimum rectilinear Steiner tree (MRST) problem. IWO meta-heuristic algorithm is proposed to meet the MRST problem more efficiently and thereby reducing the overall wire-length of interconnected nodes. Further, the proposed approach is hybridized with PSO, and a comparative analysis is performed with geosteiner 5.0.1 and existing PSO technique over minimization, consistency and convergence against available benchmark.
Findings
This paper provides high performance–enhanced IWO algorithm, which keeps in generating low MRST value, thereby successful wire length reduction of VLSI circuits is significantly achieved as evident from the experimental results as compared to PSO algorithm and also generates value nearer to geosteiner 5.0.1 benchmark. Even with big VLSI instances, hybrid IWO with PSO establishes its robustness over achieving improved optimization of overall wire length of VLSI circuits.
Practical implications
This paper includes implications in the areas of optimization of VLSI circuit design specifically in the arena of VLSI routing and the recent developments in routing optimization using meta-heuristic algorithms.
Originality/value
This paper fulfills an identified need to study optimization of VLSI circuits where minimization of overall interconnected wire length in global routing plays a significant role. Use of nature-based meta-heuristics in solving the global routing problem is projected to be an alternative approach other than conventional method.
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Ferdinando Paolo Santarpia, Valentina Sommovigo, Sara Brecciaroli, Chiara Consiglio and Laura Borgogni
By integrating the conservation of resources and the emotion-as-social-information theories, this study aims to question whether the leader’s effort to calm down when team members…
Abstract
Purpose
By integrating the conservation of resources and the emotion-as-social-information theories, this study aims to question whether the leader’s effort to calm down when team members perceive intra-team conflict (ITC) may have a counterproductive effect on their interpersonal functioning. Specifically, the authors investigated whether team members with higher individual perceptions of ITC would be more likely to experience interpersonal strain (ISW) when their team leaders downregulate or suppress their emotional responses (i.e. high interpersonal modulation of emotional responses [MER]). A further objective of the study was to examine whether this exacerbating effect would be conditional on the leader’s sex.
Design/methodology/approach
Data were collected from 236 white collars nested in 48 teams (Msize = 6.23; SDsize = 2.69) and their respective team leaders (56.7% men) of a large organization providing financial services.
Findings
Multilevel model results showed that team members confronted with higher ITC experienced higher ISW levels, especially when the leader’s interpersonal modulation of team members’ emotional responses was high (vs low). This effect was stronger when the interpersonal modulation was enacted by women (vs men) team leaders.
Originality/value
This study moves an important step forward in the conflict and ISW literature, as it is the first to identify a leader’s MER and sex as key boundary conditions under which ITC is related to team members’ ISW. The implications of these findings for theory and practice are discussed.
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Mina Heydari Torkamani, Yaser Shahbazi and Azita Belali Oskoyi
Historical bazaars, a huge treasure of Iranian culture, art and economy, are places for social capital development. Un-supervised management in past decades has led to the…
Abstract
Purpose
Historical bazaars, a huge treasure of Iranian culture, art and economy, are places for social capital development. Un-supervised management in past decades has led to the demolition and change of historical bazaars and negligence of its different aspects. The present research aims to investigate the resilience of historical bazaars preserving their identity and different developments.
Design/methodology/approach
The artificial neural network (ANN) has been applied to investigate the resilience of historical bazaars. This model consists of three main networks for evaluating the resilience of historical networks in terms of adaptability, variability and reactivity.
Findings
The ANN proposed to evaluate the resilience of historic bazaars based on the mentioned factors is efficient. By calculating mean squared error (MSE), the model accuracy for evaluating adaptability, variability and reactivity were obtained at 7.62e-25, 2.91e-24 and 1.51e-24. The correlation coefficient was obtained at a significance level of 99%. This indicates the considerable effectiveness of the artificial intelligence model in modeling and predicting the qualitative properties of historical bazaars resilience.
Originality/value
This paper clarifies indexes and components of resilience in terms of adaptability, variability and reactivity. Then, the ANN model is obtained with the least error and very high accuracy that predict the resilience of historical bazaars.
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Mahsa Mohajeri and Negin Abedi
This paper aims to examine the association between the dietary inflammatory index, the consumption of Enteral Nutrition Supplemented with probiotics with certain serum…
Abstract
Purpose
This paper aims to examine the association between the dietary inflammatory index, the consumption of Enteral Nutrition Supplemented with probiotics with certain serum inflammation markers and gastrointestinal complications among individuals diagnosed with COVID-19.
Design/methodology/approach
This cross-sectional investigation involved 100 COVID-19 patients who were admitted to intensive care units in hospitals. These patients were administered two different types of Enteral Nutrition, so the dietary inflammatory index (DII), gastrointestinal complications and some serum inflammation markers have been compared between two groups.
Findings
The mean DII scores in all patients were significantly pro-inflammatory (probiotic formula 2.81 ± 0.01 vs usual formula group 2.93 ± 0.14 p = 0.19). The probiotic formula consumption had an inverse association with High-sensitivity C-reactive Protein concentration (coef = −3.19, 95% CI −1.25, −5.14 p = 0.001) and lead to a reduction of 2.14 mm/h in the serum level of Erythrocyte sedimentation rate compared to normal formula. The incidence of diarrhea, abdominal pain and vomiting in probiotic formula patients was respectively 94%, 14% and 86% less than in usual formula patients (p = 0.05).
Originality/value
In this cross-sectional study for the first time, the authors found that probiotic formula consumption was inversely associated with serum inflammation markers and gastrointestinal complications incidence. The high DII leads to more gastrointestinal complications incidence and inflammation markers. More studies are needed to prove this relationship.
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Shi Yin, Zengying Gao and Tahir Mahmood
The aim of this study is to (1) construct a standard framework for assessing the capability of bioenergy enterprises' digital green innovation partners; (2) quantify the choice of…
Abstract
Purpose
The aim of this study is to (1) construct a standard framework for assessing the capability of bioenergy enterprises' digital green innovation partners; (2) quantify the choice of partners for digital green innovation by bioenergy enterprises; (3) propose based on a dual combination empowerment niche digital green innovation field model.
Design/methodology/approach
Fuzzy set theory is combined into field theory to investigate resource complementarity. The successful application of the model to a real case illustrates how the model can be used to address the problem of digital green innovation partner selection. Finally, the standard framework and digital green innovation field model can be applied to the practical partner selection of bioenergy enterprises.
Findings
Digital green innovation technology of superposition of complementarity, mutual trust and resources makes the digital green innovation knowledge from partners to biofuels in the enterprise. The index rating system included eight target layers: digital technology innovation level, bioenergy technology innovation level, bioenergy green level, aggregated digital green innovation resource level, bioenergy technology market development ability, co-operation mutual trust and cooperation aggregation degree.
Originality/value
This study helps to (1) construct the evaluation standard framework of digital green innovation capability based on the dual combination empowerment theory; (2) develop a new digital green innovation domain model for bioenergy enterprises to select digital green innovation partners; (3) assist bioenergy enterprises in implementing digital green innovation practices.
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Tingwei Wang, Hui Zhang and Ya Wang
The purpose of this paper is to have a deeper understanding of the nonlinear relationship between the impact of climate change on tourism development. Current studies on the…
Abstract
Purpose
The purpose of this paper is to have a deeper understanding of the nonlinear relationship between the impact of climate change on tourism development. Current studies on the effects of climate change on tourism development primarily rely on linear correlation assumptions.
Design/methodology/approach
Based on the New Institutional Economics theory, the institutional setting inherently motivates and ensures the growth of the tourism industry. For a precise evaluation of the nonlinear consequences of climate change on tourism, this paper concentrates on Chinese cities between 2011 and 2021, methodically analyzing the influence of climate change on tourism.
Findings
The study findings suggest that there is an “inverse U”-shaped nonlinear relationship between climate change and tourism development, initially strengthening and subsequently weakening. Based on these findings, the research further delves into how institutional contexts shape the nonlinear association between climate change and tourism growth. It was found that in a higher institutional backdrop, the “inverse U” curve tends to flatten and surpass the curve adjusted for a lesser institutional context. Upon deeper mechanism analysis, it was observed that cities with more advanced marketization, improved industrial restructuring and enhanced educational growth exhibit a more evident “inverse U”-shaped nonlinear connection between climate change and tourism evolution.
Originality/value
First, previous studies on climate change and tourism development largely rely on questionnaire data (Hu et al., 2022). In contrast to these studies, this paper uses dynamic panel data, which to some extent overcomes the subjectivity and difficulty of causality identification in questionnaire data, making our research conclusions more accurate and reliable. Second, this study breaks through the linear relationship hypothesis of previous literature regarding climate change and tourism development. By evaluating the nonlinear relationship of climate change to tourism development from the institutional pressure perspective, it more intricately delineates their interplay mechanism, expanding and supplementing the research literature on the relationship mechanism between climate change and tourism development. Thirdly, the conclusions of this study are beneficial for policymakers to better understand and assess the scope of climate change impacts. It also aids relevant departments in clarifying the direction of institutional environment optimization to elevate the level of tourism development when faced with adverse impacts brought about by climate change.
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Sachin Kumar, Ridhi Arora and Tapan Kumar Panda
This research aims to study the effects of mindfulness and self-compassion in addressing COVID-19 phobia issues. To date, not a single study has examined the influence of these…
Abstract
Purpose
This research aims to study the effects of mindfulness and self-compassion in addressing COVID-19 phobia issues. To date, not a single study has examined the influence of these constructs on COVID-19 phobia amongst frontline employees (FLEs) in the services sector. In this context, the present study examined the association between FLE’s trait mindfulness and COVID-19 phobia and the mediating effect of self-compassion on this relationship.
Design/methodology/approach
Data were collected using 335 FLEs working in the Indian services sector, and the analysis was undertaken using the PROCESS macro of Hayes (2018).
Findings
FLE's trait mindfulness was found to influence COVID-19 phobia negatively, and the mediation role of self-compassion was also noted. Findings for the COVID-19 phobia composite and its four facets are discussed.
Practical implications
Corporate leaders could encourage mindfulness and self-compassion training helping in buffering the negative issues associated with COVID-19 phobia among FLEs.
Originality/value
It is one of the few studies conducted in the South-Asian context that highlights how mindfulness can help enhance self-compassion among frontline service sector employees while guiding them to overcome COVID-19 phobia. This could be the first study to examine the mediating effects of self-compassion in the relationships between mindfulness and COVID-19 phobia.
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