Michail G. Christodoulou, Antonios X. Lalas, Nikolaos V. Kantartzis and Theodoros D. Tsiboukis
Metamaterials have been utilised in several exciting configurations such as tuneable reflectors, reconfigurable absorbers, and programmable modulators, triggering intense research…
Abstract
Purpose
Metamaterials have been utilised in several exciting configurations such as tuneable reflectors, reconfigurable absorbers, and programmable modulators, triggering intense research efforts. Among them, the ability to steer the radiation pattern of a single antenna component by employing a metamaterial-based superstrate is considered crucial for the development of advanced beam forming applications. The purpose of this paper is to introduce an adjustable omega-inspired metamaterial module to facilitate the design of beam steering implementations, involving beam forming capabilities, as well.
Design/methodology/approach
A variable capacitive diode is properly positioned at the novel omega element, hence advancing the controllability of its electromagnetic performance and circumventing the requirement of extra bias networks. When an array of these particles is placed in front of an antenna, several negative refractive index profiles can be realised, allowing the manipulation of the beam direction. Furthermore, a pyramidal horn antenna, loaded with this complex medium superstrate, is thoroughly investigated in terms of programmable beam steering and beam forming attributes. Several numerical data derived via the finite element method unveil the merits of the featured configuration.
Findings
The proposed structure allows programmability of the electromagnetic behaviour, but also circumvents the necessity of complicated bias networks, while minimising interference. The numerical assessment of a standard gain pyramidal horn antenna, associated to the featured metamaterial superstrate, sufficiently proves the controllable beam steering and beam forming attributes. Several parametric studies clarify the principal characteristics of the proposed setup, facilitating the design of high-end systems.
Originality/value
Development of tuneable metamaterial, which utilises variable capacitive diodes to enable controllability. Incorporation of reconfigurable metamaterials into antenna technology. Design of a pyramidal horn antenna, loaded with a complex medium superstrate exhibiting programmable beam steering and beam forming attributes. The proposed device circumvents the necessity of complicated bias networks, while minimising interference.
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Keywords
Antonios X. Lalas, Nikolaos V. Kantartzis and Theodoros D. Tsiboukis
Metamaterials are artificially tailored complex media with extraordinary properties, not available in nature. Due to their unique performance, they are considered as a crucial…
Abstract
Purpose
Metamaterials are artificially tailored complex media with extraordinary properties, not available in nature. Due to their unique performance, they are considered as a crucial component of modern radio-frequency technology, especially in the THz regime. However, their lack of wide spectral bandwidths introduce constraints for realistic applications. The purpose of this paper is to propose piezoelectric micro-electromechanical systems (MEMS) actuators to modify the shape of electric field-driven LC (ELC) resonators. A THz modulation capability is revealed by connecting/disconnecting the associated metal parts.
Design/methodology/approach
Piezoelectric MEMS actuators are proposed to provide the desired bandwidth enhancement along with THz modulation. Two setups with different degrees of freedom in altering the behaviour of the novel modulator are investigated. A variety of numerical data, acquired via the finite element method, substantiate the advantageous characteristics of the proposed structures.
Findings
The novel devices enable the modification of the structural features of an ELC-based complex medium, unveiling in this manner a significant THz modulation capability along with improved bandwidth tunability. Two discrete cases are presented involving different degrees of freedom to shape the overall performance of the metamaterial modulator.
Originality/value
Development of a THz modulator, which utilises metamaterials as its fundamental component. Incorporation of tunable piezoelectric metamaterials into THz technology allowing increased reconfigurability. Bandwidth enhancement of metamaterial systems and alternative design via multiple controllable gaps enabling more degrees of freedom for design purposes.
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Antonios X. Lalas, Nikolaos V. Kantartzis and Theodoros D. Tsiboukis
Wireless power transfer (WPT) is deemed as an emerging technology with exciting applications, like wireless charging devices, and electric vehicles, whereas metamaterials exhibit…
Abstract
Purpose
Wireless power transfer (WPT) is deemed as an emerging technology with exciting applications, like wireless charging devices, and electric vehicles, whereas metamaterials exhibit exceptional properties. For every WPT system that occupies coupled magnetic resonances, it is also mandatory to involve resonators. The purpose of this paper is to introduce a new interdigitated split-ring resonator (I-SRR) as the basic part of a WPT system, pursuing advanced levels of efficiency.
Design/methodology/approach
A novel WPT system, which exploits I-SRRs as its elementary blocks, is comprehensively examined. The analysis investigates the distance between the modules, the distance between transmitting and receiving components as well as the geometrical features of the structure. Several numerical data derived via the finite element method unveil the merits of the featured configuration.
Findings
The proposed arrangement reveals a noteworthy enhancement of the power delivered to the load and a promising tuning of the operational frequency via the interdigitated topology. Several parametric studies clarify the principal characteristics of the proposed setup, facilitating the design of high-end systems. In particular, the distance between the resonators and the port loops affect the matching of the input and output ports, allowing optimisation of power efficiency, while the length of the I-SRR gap can determine the operational frequency.
Originality/value
Development of a WPT system, which utilises I-SRRs as its key elements. Incorporation of metamaterials into WPT technology. Efficiency enhancement of WPT systems and alternative design via geometrical modifications. The necessity of lumped elements to implement the WPT resonators is eliminated by utilising split-ring resonators components, enabling compactness in several implementations.
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Haritz Gorostidi-Martinez, Weimin Xu and Xiaokang Zhao
As part of a cross-cultural research, the purpose of this paper is to provide further insights into the existing product-country image (PCI) of the Chinese consumers’ perceptions…
Abstract
Purpose
As part of a cross-cultural research, the purpose of this paper is to provide further insights into the existing product-country image (PCI) of the Chinese consumers’ perceptions of Spain, its products, and its people, thereby providing an overall contemporary Spanish PCI within the Chinese market.
Design/methodology/approach
In total, 215 valid structured questionnaires were gathered throughout China. Following a pre-investigation of 259 usable questionnaires, a 52-item construct was drawn from the existing widely used PCI item scales, designing a structured PCI construct, covering: “country image,” “personal image,” “product image,” “general knowledge about Spain,” and “personal data.”
Findings
The study provides: a PCI pre-investigation research results as well as a literature review on PCI topic; research results for the five hypotheses concerning Chinese citizens’ view of Spanish product price, quality, technicality, inventiveness, and known brands view; descriptive statistics as well as result graphs for each of the covered PCI sections; our PCI construct variable correlations with the tested five product image variables; and general implications.
Research limitations/implications
Standardizing PCI longitudinal studies, as well as focusing on how the Spanish Government and private sector should determine the long-term criteria to facilitate a clearer representation of the Spanish PCI evolution within the Chinese market, is advised.
Originality/value
The current study intends to capture insights for Spain and other country’s public and private sector decision makers to better integrate market and non-market strategies. The results would further assist delineating strategies to avoid the liability of foreignness of Spanish organizations within China.
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Jun Wen, Carol Chunfeng Wang, Edmund Goh, Zhaohui Su and Tianyu Ying
This paper explores the role of traditional Chinese medicine (TCM) as a tourism recovery drawcard to boost China's inbound tourism after COVID-19.
Abstract
Purpose
This paper explores the role of traditional Chinese medicine (TCM) as a tourism recovery drawcard to boost China's inbound tourism after COVID-19.
Design/methodology/approach
This paper employed a mixed method involving a cross-disciplinary literature review along with reflections from experts in TCM and health communication to inform tourism management. Specifically, this paper examines TCM and its potential benefits as a medical tourism drawcard to combat COVID-19. The selected literature focusses on the image and merits of TCM to frame how this medical philosophy can be used to position China as a tourist destination. Reflections on the use of TCM as a tourism marketing tool can guide promotional strategies from the Chinese government and destination managers during and after COVID-19.
Findings
The Chinese government, the tourism industry (e.g. destination managers), the media and tourists must focus on three aspects of the role of TCM: to provide medical benefits to travellers amid COVID-19 and beyond, elevate China as a destination for global medical tourists and be leveraged as a tool for economic recovery.
Practical implications
The paper builds a tourism recovery framework for stakeholders to adopt tailored TCM communication strategies to boost its inbound tourism programme.
Originality/value
This paper is the first academic paper to review TCM comprehensively and critically in relation to China tourism and post-COVID-19 recovery measures.
Details
Keywords
Sanjeev Shrivastava and Shrivastava R.L.
The purpose of this paper is to survey the technical performance of the cement industry including those related to procedures; groundwork of raw materials, fuels and semi-finished…
Abstract
Purpose
The purpose of this paper is to survey the technical performance of the cement industry including those related to procedures; groundwork of raw materials, fuels and semi-finished products for processing; accessibility of machinery, plant and equipment for various operations; arrangement and process control management.
Design/methodology/approach
A broad range of survey and research was reviewed, and all revealed the methods to recognize the key influences for development of green technology. The study explores the present scenario of green manufacturing (GM) strategies of Indian cement companies and provides the industrial ecology, ways of reducing energy consumption, environmental impact data collection, design and control of manufacturing systems and integration of product and manufacturing system. It also reveals the problems in decision-making systems owing to the impact of the green product design. Here, in this paper, all information is obtained by the medium of internet, journals, articles, and magazines.
Findings
This paper describes a problem of global warming, gas, water and other wastages emissions at the time of cement manufacturing and put forward a path that enables decision makers to assess the perception of GM in their organization and in prioritizing GM efforts.
Originality/value
This perspective survey is to provide an integrative outlook of performance methods for GM practices in the Indian cement industries. It gives important information, which expectantly will help in cement industry to adopt GM practices. This paper fills the gap in the literature on identification, establishment, and validation of performance measures of GM for Indian cement industries.
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Megan Burfoot, Amirhosein Ghaffarianhoseini, Nicola Naismith and Ali GhaffarianHoseini
Informed by acoustic design standards, the built environments are designed with single reverberation times (RTs), a trade-off between long and short RTs needed for different space…
Abstract
Purpose
Informed by acoustic design standards, the built environments are designed with single reverberation times (RTs), a trade-off between long and short RTs needed for different space functions. A range of RTs should be achievable in spaces to optimise the acoustic comfort in different aural situations. This paper proclaims a novel concept: Intelligent passive room acoustic technology (IPRAT), which achieves real-time room acoustic optimisation through the integration of passive variable acoustic technology (PVAT) and acoustic scene classification (ASC). ASC can intelligently identify changing aural situations, and PVAT can physically vary the RT.
Design/methodology/approach
A qualitative best-evidence synthesis method is used to review the available literature on PVAT and ASC.
Findings
First, it is highlighted that dynamic spaces should be designed with varying RTs. The review then exposes a gap of intelligently adjusting RT according to changing building function. A solution is found: IPRAT, which integrates PVAT and ASC to uniquely fill this literature gap.
Originality/value
The development, functionality, benefits and challenges of IPRAT offer a holistic understanding of the state-of-the-art IPRAT, and a use case example is provided. Going forward, it is concluded that IPRAT can be prototyped and its impact on acoustic comfort can be quantified.
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Keywords
Sousana K. Papadopoulou, Maria Mantzorou, Desspina Koutridou, Elias Tassoulas, Styliani Sakellaropoulou, Fani Biskanaki, Efthymis Xatziapostolou and Dimitrios Papandreou
The purpose of this paper is to critically summarize the current data concerning the impact of obesity and micronutrient adequacy and supplementation on the risk and severity of…
Abstract
Purpose
The purpose of this paper is to critically summarize the current data concerning the impact of obesity and micronutrient adequacy and supplementation on the risk and severity of COVID-19 disease, and their potential impact on treatment and rehabilitation.
Design/methodology/approach
PubMed, Scopus and Google Scholar databases were thoroughly searched to identify studies concerning obesity and nutritional status, vitamin and other micronutrients adequacy with COVID-19 severity.
Findings
Individuals with higher body mass index are in greater risk of severe disease and need for mechanical ventilation. Concerning micronutrient adequacy, no published studies at the present time have evaluated the effect of supplementation on the risk and the treatment of the novel disease.
Originality/value
Recently, COVID-19 has monopolized the interest of the medical community regarding diet and nutritional status and it possibly plays an important role in disease severity.