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Spurious modes often appear in the computed spectrum when an electromagnetic eigenproblem is solved by the finite element method. Demonstrates that the inclusion condition, often claimed as the theoretical reason for the absence of (non‐zero frequency) spurious modes, is a sufficient but not necessary condition for that. Does this by proving that edge elements, which are spectrally correct, do not satisfy the inclusion condition. As intermediate steps towards this result, proves the equivalence of the inclusion condition to a less cryptic one and gives two more easily‐checked necessary conditions for the latter. Concludes that from this investigation, the inclusion condition seems too strong to be useful as a sufficient condition. Works out the present analysis in the framework of spectral approximation theory for non‐compact operators, which emerges as a basic tool for a deeper understanding of the whole question of spurious modes.

From a theoretical point of view the question of spurious modes has been regarded as a closed problem. However, in this paper we show that even a precise definition of spurious‐free approximation was lacking. Hence, a sound definition of spurious‐free finite element method is given and a set of necessary and sufficient conditions ensuring that a finite element method is spurious‐free in the defined sense is stated. A critical comparison between the proposed theory and the currently accepted one is then carried out and existing counterexamples to the latter are pointed out. Comparison with an older theory leads to another set of necessary and sufficient conditions providing a better grasp of the key feature a finite element space must have to rule out spurious modes. The impact of the proposed theory is stressed, showing that Nedelec's tetrahedral edge elements of all orders provide spurious‐free approximations in all conditions of practical interest. Finally, it is shown, for the first time to the best of authors’ knowledge, that also many high‐order edge elements, recently proposed in the engineering literature for the analysis of electromagnetic problems, provide the same kind of reliable approximation.

To provide sufficient conditions for existence, uniqueness and finite element approximability of the solution of time‐harmonic electromagnetic boundary value problems involving metamaterials.

The objectives are achieved by analysing the most simple conditions under which radiation, scattering and cavity problems are well posed and can be reliably solved by the finite element method. The above “most simple conditions” refer to the hypotheses allowing the exploitation of the simplest mathematical tools dealing with the well posedness of variationally formulated problems, i.e. Lax‐Milgram and first Strang lemmas.

The results of interest are found to hold true whenever the effective dielectric permittivity is uniformly positive definite on the regions where no losses are modelled in it and, moreover, the effective magnetic permeability is uniformly negative definite on the regions where no losses are modelled in it. The same good features hold true if “positive” is replaced by “negative” and vice versa in the previous sentence.

It is a priori known that more sophisticated mathematical tools, like Fredholm alternative and compactness results, can provide more general results. However this would require a more complicated analysis and could be considered in a future research.

The design of practical devices involving metamaterials requires the use of reliable electromagnetic simulators. The finite element method is shown to be reliable even when metamaterials are involved, provided some simple conditions are satisfied.

For the first time to the best of authors' knowledge a numerical method is shown to be reliable in problems involving metamaterials.

Ground Penetrating Radar is a multidisciplinary Nondestructive Evaluation technique that requires knowledge of electromagnetic wave propagation, material properties and antenna theory. Under some circumstances this tool may require auxiliary algorithms to improve the interpretation of the collected data. Detection, location and definition of target’s geometrical and physical properties with a low false alarm rate are the objectives of these signal post-processing methods. Basic approaches are focused in the first two objectives while more robust and complex techniques deal with all objectives at once. This work reviews the use of Artificial Neural Networks and Machine Learning for data interpretation of Ground Penetrating Radar surveys. We show that these computational techniques have progressed GPR forward from locating and testing to imaging and diagnosis approaches.

This paper aims to develop and describe an improved process for determining the rate of heat generation in living tissue.

Previous work by the authors on solving the bioheat equation has been updated to include a new localized meshless method which will create a more robust and computationally efficient technique. Inclusion of this technique will allow for the solution of more complex and realistic geometries, which are typical of living tissue. Additionally, the unknown heat generation rates are found through genetic algorithm optimization.

The localized technique showed superior accuracy and significant savings in memory and processor time. The computational efficiency of the newly proposed meshless solver allows the optimization process to be carried to a higher level, leading to more accurate solutions for the inverse technique. Several example cases are presented to demonstrate these conclusions.

This work includes only 2D development of the approach, while any realistic modeling for patient‐specific cases would be inherently 3D. The extension to 3D, as well as studies to improve the technique by decreasing the sensitivity to measurement noise and to incorporate non‐invasive measurement positioning, are under way.

As medical imaging continuously improves, such techniques may prove useful in patient diagonosis, as heat generation can be correlated to the presence of tumors, infections, or other conditions.

This paper describes a new application of meshless methods. Such methods are becoming attractive due to their decreased pre‐processing requirements, especially for problems involving complex geometries (such as patient specific tissues), as well as optimization problems, where geometries may be constantly changing.

The purpose of this paper is to identify the factors that could help differentiate between successful and unsuccessful small- and medium-sized exporter firms.

A causal model of the exporting process was developed from the literature, from which a set of hypotheses was posed and a questionnaire was made. A sample of 37 small and medium exporter firms in Chile was subject to the questionnaire. From the data collected, the critical aspects that could help differentiate between successful and unsuccessful exporting organizations were statistically identified.

The following aspects are the ones that could allow the statistical differentiation of successful and unsuccessful exporter firms: incentives at the firm level for increasing output, improved operations planning, international quality assurance certification, large percentage of sales devoted to innovation, highly frequent innovations, qualified and innovative workers, local alliances for innovation, and the possession of strategic allies at destination

The results of this research can be useful for intending small and medium exporter firms in Chile, as well as for firms in other developing countries. The results are based on a rather small sample of exporting firms in Chile; therefore, the generalizability of the results cannot be assured

A detailed model of the exporting process of small and medium firm (SMF) was developed that is a contribution of the theoretical framework related to SMFs’ exports. The findings could be used by government agencies to offer better guidance to SMF intending to become exporters

The purpose of this study is to explore how food-exporting firms assess the importance of relationship characteristics of the supply chain that impact their performance as well as how it relates to export performance indicators.

An online survey was administered across 83 food firms in Greece, assessing the importance of relationship characteristics of the supply chain by using the best–worst scaling technique.

The most important characteristics relate to the quality of the primary material and the procurement costs and producer prices; these are considered more important by export-oriented food firms compared to non–export-oriented food firms. Characteristics that relate to the relationship between members of the agri-food supply chain and the interorganizational business systems and governance mechanisms are also considered of average importance. Characteristics related to the adoption of differentiation strategies are considered least important.

Producers should emphasize the quality and prices of their product as well as establish collaborations with food firms. Food firms need to emphasize interorganizational business systems and governance mechanisms that reduce procurement costs, instead of trying to reduce producer prices. Public authorities should engage stakeholders of the agri-food supply chain in relationships that will enable food firms to deliver on their quality and price demands.

Primary production and collaborations of it with food firms have not been studied in regards to what extent they relate to food firms' export performance.

The purpose of this paper is to investigate the network promotion role of export promotion programmes in driving small and medium enterprises’ (SMEs) export performance.

Drawing on a dual institutional and network-based approaches to internationalisation, the study tests an integrative model that explores the mediating role of SMEs’ relationships in the link between government export promotion programmes (both informational and experiential forms) and export performance. The model was tested using a sample of 160 UK small and medium exporter firms. The data were analysed through a structural equation modelling technique.

The study finds that whilst both informational and experiential export promotion programmes improved all forms of SMEs’ relationships, only experiential forms had an indirect effect on export performance. Further, only relationships with foreign buyers had a positive impact on export performance.

The results of this research provide directions for export promotion organisations in targeting their network support provision and for SMEs in utilising such a support. The study calls for similar research in different contexts to validate the proposed model.

This study brings novel findings to the extant literature by conceptualising and validating the importance of the “network promotion” element of export promotion programmes.

The paper analyses the influence of the decision-makers' overconfidence on the intuitive practices' adoption, as well as on the international performance during international strategic decision-making processes (SDMPs) of small- and medium-sized enterprises (SMEs). Moreover, the study investigates the possible mediating effect of intuition on the relationship between overconfidence and international performance.

A semi-structured questionnaire based on a sample of 160 SMEs and a regression analysis have been employed.

Results show a negative relationship between intuition and international performance and a positive one between overconfidence and international performance. Furthermore, a negative relation between overconfidence and intuition has been identified. Findings also highlight the mediating role of intuition in the relationship between overconfidence and international performance.

The paper provides valuable implications related to the analysis of overconfidence as a critical decision-maker's character and intuition as a feature of the decision-making methodology. Moreover, the study offers indications for SMEs facing complex strategic decisions.

The paper adopts an original perspective by combining the SDMP analysis with that of international strategy within the SMEs context. Additionally, the study enriches the existing literature by (1) investigating overconfidence in the decision-making; (2) enhancing the examination of overconfidence and intuitive practices in the international SDMP; (3) deepening the research field focused on the identification of the intuitive processes' predictors that is still in its infancy.