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Faltung equations (closed cycle type) have a wide range of biological applications, nonetheless, they are poorly studied. We use a Volterra‐Kostitzin model (which is a Faltung equation) to study the dynamics of a certain species, where the integral term represents a residual action. The complexity of resolution of this non‐linear equation using classical numeric methods is here solved with the Adomian decomposition method. Our method provides the same graphic solution as others do, such as the numeric method Miladie. However, the decomposition method of Adomian has the advantage that neither time nor space are considered discontinuous and that it gives an analytical solution with a reliable approximation.

In this paper the authors aim to show the advantages of using the decomposition method introduced by Adomian to solve Emden's equation, a classical non‐linear equation that appears in the study of the thermal behaviour of a spherical cloud and of the gravitational potential of a polytropic fluid at hydrostatic equilibrium.

In their work, the authors first review Emden's equation and its possible solutions using the Frobenius and power series methods; then, Adomian polynomials are introduced. Afterwards, Emden's equation is solved using Adomian's decomposition method and, finally, they conclude with a comparison of the solution given by Adomian's method with the solution obtained by the other methods, for certain cases where the exact solution is known.

Solving Emden's equation for n in the interval [0, 5] is very interesting for several scientific applications, such as astronomy. However, the exact solution is known only for n=0, n=1 and n=5. The experiments show that Adomian's method achieves an approximate solution which overlaps with the exact solution when n=0, and that coincides with the Taylor expansion of the exact solutions for n=1 and n=5. As a result, the authors obtained quite satisfactory results from their proposal.

The main classical methods for obtaining approximate solutions of Emden's equation have serious computational drawbacks. The authors make a new, efficient numerical implementation for solving this equation, constructing iteratively the Adomian polynomials, which leads to a solution of Emden's equation that extends the range of variation of parameter n compared to the solutions given by both the Frobenius and the power series methods.

The paper presents a techno-economic analysis of the electromechanical equipment of traditional vertical axis water mills (VAWMs) to help investors, mill owners and engineers to preliminary estimate related benefits and costs of a VAWM repowering.

Two sustainable repowering solutions were examined with the additional aim to preserve the original status and aesthetics of a VAWM: the use of a vertical axis water wheel (VAWW) and a vertical axis impulse turbine. The analysis was applied to a database of 714 VAWMs in Basilicata (Italy), with known head and flow.

Expeditious equations were proposed for both solutions to determine: (1) a suitable diameter as a function of the flow rate; (2) the costs of the electromechanical equipment; (3) achievable power. The common operating hydraulic range of a VAWM (head and flow) was also identified. Reality checks on the obtained results are shown, in particular by examining two Spanish case studies and the available literature. The power generated by the impulse turbine (Turgo type) is twice that of a VAWW, but it is one order of magnitude more expensive. Therefore, the impulse turbine should be used for higher power requirements (>3 kW), or when the electricity is delivered to the grid, maximizing the long-term profit.

Since there is not enough evidence about the achievable performance and cost of a VAWM repowering, this work provides expeditious tools for their evaluation.

The purpose of this paper is to compare the practices of continuous improvement that are applied in medium and large manufacturing and service companies in two Latin American countries. At the same time, benefits and barriers experienced by these companies with regard to sustainability of continuous improvement are explored.

In order to generate a comparative study between two Latin American countries, interviews were conducted with managers linked to continuous improvement in medium and large companies in the State of Puebla and the Metropolitan District of Quito, which are important areas in Mexico and Ecuador, respectively. Data were collected by means of document analysis, semi-structured interviews, and direct observation.

Companies in both countries identify the use of various techniques and/or tools for continuous improvement. The results of the empirical evidence show how the impact of the application of the techniques has been beneficial in economic and human terms. Thus, the exploratory study has permitted the identification of the drivers and inhibitors in the maintenance of continuous improvement.

The research is based on only two areas of the Latin American countries: Mexico and Ecuador. Their results can therefore not be generalized. The approach is applied in a specific environment, namely, the State of Puebla and the Metropolitan District of Quito. This study incorporates the perception of managers, directors, and/or supervisors involved in continuous improvement processes.

This paper seeks to provide analytical input. The study is of great interest to researchers, managers, consultants, and professionals linked to projects of continuous improvement who wish to incorporate continuous improvement practices which are sustainable over time. A new managerial behavior is the basis of continuous improvement, where the training and development of the human resource increases the commitment to achieve organizational changes.

This research makes an empirical contribution to the literature through the understanding of practices of continuous improvement in a Latin American context, highlighting the factors that improve or impede the process of continuous improvement. Particularly in Mexico and Ecuador, the empirical evidence on this subject is still scarce despite the existence of theoretical academic literature.

This study aims to identify the current state, the emergent research clusters, the key research topics and the configuration of collaboration in scientific production related to the market value of soccer players.

This article analyzes 52 articles published between 1985 and 2021 and from the Scopus and WoS databases.

The subject is of growing interest both in academic and practical areas. A variable that frequently appears as a determinant of market value is crowd wisdom. The largest cluster related to the co-citation level shows that the main issues about soccer player market value are player performance, team performance, and the determinants of the superstar formation. Spain and Germany stand out as essential countries both in literary production and citation rate. The network of collaborations is still low.

This study is supported by databases being constantly updated, resulting in continuous variation in the number of indexed journals. Consequently, a bibliometric analysis regarding an emergent topic can, in fewer years, be subject to essential variations. Another limitation is that it has analyzed a particular topic using the most influential databases, and the global perspective could be improved with the incorporation of other different databases. Data regarding collaborations could be helpful for investigations or policies that propose to approach the topic supported by specialized groups. This study offers the possibility for future researchers to extend the databases used, the level of analysis, or focus on specific topics or variables affecting the soccer player market value.

This study contributes to knowing the current state of the soccer player market value research. Studies on such topics are relatively limited concerning the literature review.

This study aims to contribute to the professional competency approach in Education for Sustainability (ES) from the perspective of complexity and to the assessment of these competencies.

A qualitative research process was used, which consisted of two main phases: a documentary analysis of the internationally accepted frameworks about professional competencies in ES and complexity and a case study. The context was the Learning Camp of Cistercian Monasteries (Catalonia, Spain), and two educators participated in this camp.

The main outcomes are: a framework of professional competencies in ES from a complexity perspective, called CESC, and a rubric, as an assessment tool for professional competences in ES.

Based on the results, the author’s can state that this research is a contribution to the ES competency approach and it rectifies the lack of assessment tools in this area. The CESC is a theoretical contribution that facilitates educators’ development of ES competencies based on complexity. The design of the rubric with a high level of applicability and transferability is a methodological contribution which facilitates the assessment of these competencies by educators, as individuals, and educational teams. Related to the case study, several guidelines are proposed regarding the need for educator training to advance in the mobilisation of competencies in ES.

This paper aims to report on a case study concerning the development of sustainable energy partnerships involving engineering faculty and undergraduate students at the University of Girona, Catalonia, Spain.

Faculty were motivated to seek partnerships with public and private entities in the local area for the purposes of realising mutually beneficial outcomes. The educational programmes of future engineers, when sustainability is considered, are analysed. Education for sustainable development has to include multidisciplinary active learning as a desirable competence. Active learning can be obtained when problems are based on real life because they are most motivating for students. Constructive alignment component is obtained because learning objectives are linked with learning activities related to the needs of public and private entities.

Through the provision of technical expertise, the adoption and success of renewable energy projects was facilitated on the one hand, while final year undergraduate students benefited in terms of hands-on experience in helping to bring these projects to life, drawing on the knowledge and skills they had acquired throughout their degree programmes. These works are addressed to students by faculty members with the aim of developing and promoting renewable energies. Outcomes from partnerships surpassed expectations; not only were different benefits realised as were initially hoped for, but this success led to partnerships being sustained over time.

Fossil fuel-based energy systems are associated with a myriad of negative environmental and social externalities. It is difficult to overstate the importance of transitioning towards alternative low carbon energy sources for climate change mitigation which are less centralised compared to the status-quo for energy security and energy independence. By actively facilitating the development of decentralised renewable energy sources in Catalonia, the projects reported herein are of significant value in social environmental and educational terms.

The issue of linguistic autonomy is a central one on the agenda of Catalan politics within the Spanish state. In the transition from Francoism, virtually all political groups in Catalonia supported a statute of autonomy (1982) which declares that “Catalan is the official language of Catalonia, as is Castillian, the official language of the entire Spanish State.”

Recently, several areas are successfully applying the Lean Six Sigma methodology, specifically in healthcare, public services, higher education institutions and manufacturing industries. This study aims to present an extensive literature review involving Lean Six Sigma practical applications in the last five years, described in a case studies format.

A systematic literature review was conducted, and 39 articles were selected and analyzed.

An increase in Lean Six Sigma applications in healthcare and higher education institutions was identified. Furthermore, Lean Six Sigma is effectively applied in several areas and is continuously used in traditional industries. The main critical success factor identified was leadership and management involvement, project management and organizational infrastructure, as well as training and education. Also, the main difficulties found are related to the organization's culture and developing communication with leaders and managers.

The main difficulties found in this research are related to the lack of data presented in some articles analyzed, where only information about how the Lean Six Sigma application was conducted is shown, not mentioning difficulties or success factors identified.

Case studies are fundamental to help popularize Lean Six Sigma applications, showing a real-life scenario of how the methodology is implemented, the main difficulties encountered and critical success factors found. Thus, the value of this study is promoting and developing research involving Lean Six Sigma case study applications to guide new researchers and practitioners on the subject.