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Abstract: Today, the concept of a circular economy (CE) has become omnipresent. Central to this concept is the term value, however, it is not properly defined, which leads to different interpretations, and hinders implementation of the CE concept. Hence, this article operationalizes the theoretical concept of value into a more practical understanding. First, the meaning of value within the CE context is examined, followed by the development of a framework wherein value is decomposed into two essential types; functional and created value. Next, the framework is applied to an illustrative case study involving four different end-of-life strategies: landfilling, closed loop recycling, remanufacturing and reusing. The framework enables a holistic comparison of the different strategies, represented in a visually compelling way, and clarifies the connection between theoretical CE concepts and practical measures. Consequently, it enhances the understanding of existing CE indicators and serves as a stepstone for the development of new indicators.

Abstract With drastic fossil fuel depletion and environmental deterioration concerns, a move towards a more sustainable bioenergy-based economy is essential. Lately, the application of microwave (MW) irradiation for waste processing has been attracting interest globally. MW-assisted heating possesses several advantages such as the provision of high microwave energy into dielectric materials with deeper penetration for internal heat generation, showing beneficial features in improving the heating rate and reducing the reaction time. Consequently, the most recent literature regarding the applications of MW-assisted heating for biomass pretreatment as well as biofuel and bioenergy production was reviewed and consolidated in this study. An impressive increase in the product yield and improvement of the product properties are reported, with the use of MW-assisted heating in several conversion routes to produce biofuels. Despite being a promising technology for biofuel production, some major fundamental data of MW-assisted heating have not been comprehensively identified. Therefore, the feasibility of this technology for large-scale implementation is still subpar. Understanding the interaction between the feedstock and the microwave electromagnetic field, and the optimization of several operational and mechanical parameters are the two main keystones that would propel the industrialization of MW heating in the near future. This provides key insights leading to increased feasibility and more advanced application of MW heating.

Achieving environmental sustainability has become a global concern amidst increasing climate change threat. Using quarterly frequency data for the case of Russia from 1992 to 2018, the present study explores the interaction between disaggregated energy consumption (renewable energy and non-renewable energy), trade flow and economic growth on a broader measure for environmental degradation (ecological footprint). The choice of the variables draws strength from initiative of the United Nations Sustainable Development Goals (UN-SDG, 7, 8 11 and 13) for responsible energy consumption and clean energy consumption while mitigating climate change issues. The study applied the quantile-on-quantile regression (QQR) and nonparametric causality-in-quantiles to capture these associations. The outcomes from the QQR disclosed that in the majority of the quantiles, trade openness and renewable energy use contribute to environmental sustainability, while nonrenewable energy amplifies ecological footprint. Furthermore, growth in Russia escalates its ecological footprint. Moreover, in the majority of the quantiles, all the exogenous variables can predict ecological footprint. Given the outcomes of this study, it outlines the need for a paradigm shift for alternative and clean energy consumption in Russian energy mix amidst its economic growth trajectory while accounting for green-development approaches. Pathways to fully achieve the sustainability targets are carefully outlined in the concluding section.

Solar thermal collectors convert sunlight into useful thermal energy by absorbing its incoming radiation. Concentrated solar power technologies use the parabolic trough solar collector to collect solar energy with temperatures ranging from 325– 700 K. The tangent hyperbolic fluid model is one of the most important non-Newtonian fluid models. Laboratory studies demonstrate that this model accurately predicts the shear thinning phenomenon. In addition, tangent hyperbolic fluid has a better heat transfer performance due to its rheological bearing at various shear rates. The current study investigates the heat transmission performance of Darcy–Forchheimer tangent hyperbolic radiative inclined cylindrical film movement in parabolic trough solar collector with an irregular heat sink/source utilizing the Levenberg–Marquardt technique and backpropagated neural networks. Through the implementation of required transformations, this system is turned into an equivalent nonlinear ordinary differential system. The findings are investigated for Newtonian and tangent hyperbolic fluid cases to understand the rheological characteristics. The outcomes are considered using graphical and mathematical evaluations. Fluids featuring tangent hyperbolic rheological conductivity are obligatory for active rate of heat diffusion. As a consequence, these fluids may be employed in Parabolic Trough Solar Collector for increased heat transmission rate and operational usage of solar energy. Furthermore, We create a dataset using the Runge–Kutta fourth-order shooting technique to create the proposed multilayer perceptron artificial neural network. The data points representing the MoD values are observed to be closely clustered around the zero deviation line. Additionally, it is important to highlight that these data points have relatively small numerical values. Moreover, when calculating the average MoD values for each output, it becomes evident that they are consistently very low.

Alors que les répercussions négatives de la dévastation environnementale, telles que le réchauffement climatique et le changement climatique, deviennent de plus en plus évidentes, la conscience environnementale se développe dans le monde entier, obligeant les nations à prendre des mesures pour atténuer les dommages. Ainsi, la présente étude évalue l'effet des investissements verts, de la qualité institutionnelle et de la stabilité politique sur la qualité de l'air dans les pays du G20 pour la période 2004-2020. La stationnarité des variables a été examinée avec le CADF Pesaran (J Appl Econ 22: 265-312, 2007), la relation à long terme entre les variables par Westerlund (Oxf Bull Econ Stat 69(6) : 709-748, 2007), les coefficients de relation à long terme avec la méthode MMQR proposée par Machado et Silva (Econ 213(1) : 145-173, 2019), et la relation de causalité entre les variables par Dumitrescu et Hurlin (Econ Model 29(4) :1450-1460, 2012). Les résultats de l'étude ont révélé que les investissements dans la finance verte, la qualité institutionnelle et la stabilité politique augmentaient la qualité de l'air, tandis que la production totale et la consommation d'énergie diminuaient la qualité de l'air. La causalité du panel révèle une causalité unidirectionnelle des investissements dans la finance verte, de la production totale, de la consommation d'énergie et de la stabilité politique à la qualité de l'air, et une causalité bidirectionnelle entre la qualité institutionnelle et la qualité de l'air. Selon ces résultats, il a été constaté qu'à long terme, les investissements dans la finance verte, la production totale, la consommation d'énergie, la stabilité politique et la qualité des institutions affectent la qualité de l'air. Sur la base de ces résultats, des implications politiques ont été proposées. A medida que las repercusiones negativas de la devastación ambiental, como el calentamiento global y el cambio climático, se hacen más evidentes, la conciencia ambiental está creciendo en todo el mundo, lo que obliga a las naciones a tomar medidas para mitigar el daño. Por lo tanto, el presente estudio evalúa el efecto de las inversiones verdes, la calidad institucional y la estabilidad política en la calidad del aire en los países del G-20 para el período 2004-2020. La estacionariedad de las variables se examinó con el CADF Pesaran (J Appl Econ 22: 265-312, 2007), la relación a largo plazo entre las variables por Westerlund (Oxf Bull Econ Stat 69(6): 709-748, 2007), los coeficientes de relación a largo plazo con el método MMQR propuesto por Machado y Silva (Econ 213(1):145-173, 2019), y la relación de causalidad entre las variables por Dumitrescu y Hurlin (Econ Model 29(4):1450-1460, 2012) causalidad del panel. Los hallazgos del estudio revelaron que las inversiones en finanzas verdes, la calidad institucional y la estabilidad política aumentaron la calidad del aire, mientras que la producción total y el consumo de energía disminuyeron la calidad del aire. La causalidad del panel revela una causalidad unidireccional desde las inversiones en finanzas verdes, la producción total, el consumo de energía y la estabilidad política hasta la calidad del aire, y una causalidad bidireccional entre la calidad institucional y la calidad del aire. De acuerdo con estos hallazgos, se ha encontrado que a largo plazo, las inversiones en finanzas verdes, la producción total, el consumo de energía, la estabilidad política y la calidad institucional afectan la calidad del aire. Con base en estos resultados, se propusieron implicaciones políticas. As the negative repercussions of environmental devastation, such as global warming and climate change, become more apparent, environmental consciousness is growing across the world, forcing nations to take steps to mitigate the damage. Thus, the current study assesses the effect of green investments, institutional quality, and political stability on air quality in the G-20 countries for the period 2004-2020. The stationarity of the variables was examined with the Pesaran (J Appl Econ 22:265-312, 2007) CADF, the long-term relationship between the variables by Westerlund (Oxf Bull Econ Stat 69(6):709-748, 2007), the long-run relationship coefficients with the MMQR method proposed by Machado and Silva (Econ 213(1):145-173, 2019), and the causality relationship between the variables by Dumitrescu and Hurlin (Econ Model 29(4):1450-1460, 2012) panel causality. The study findings revealed that green finance investments, institutional quality and political stability increased the air quality, while total output and energy consumption decreased air quality. The panel causality reveals a unidirectional causality from green finance investments, total output, energy consumption and political stability to air quality, and a bidirectional causality between institutional quality and air quality. According to these findings, it has been found that in the long term, green finance investments, total output, energy consumption, political stability, and institutional quality affect air quality. Based on these results, policies implications were proposed. نظرًا لأن التداعيات السلبية للدمار البيئي، مثل الاحترار العالمي وتغير المناخ، أصبحت أكثر وضوحًا، فإن الوعي البيئي ينمو في جميع أنحاء العالم، مما يجبر الدول على اتخاذ خطوات للتخفيف من الضرر. وبالتالي، تقيّم الدراسة الحالية تأثير الاستثمارات الخضراء والجودة المؤسسية والاستقرار السياسي على جودة الهواء في دول مجموعة العشرين للفترة 2004-2020. تم فحص ثبات المتغيرات مع Pesaran (J Appl Econ 22: 265-312، 2007) CADF، والعلاقة طويلة الأجل بين المتغيرات بواسطة Westerlund (Oxf Bull Econ Stat 69(6): 709-748، 2007)، ومعاملات العلاقة طويلة المدى مع طريقة MMQR التي اقترحها Machado و Silva (Econ 213(1): 145-173، 2019)، والعلاقة السببية بين المتغيرات بواسطة Dumitrescu و Hurlin (Econ Model 29(4): 1450-1460، 2012) لوحة السببية. وكشفت نتائج الدراسة أن استثمارات التمويل الأخضر والجودة المؤسسية والاستقرار السياسي زادت من جودة الهواء، في حين أدى إجمالي الإنتاج واستهلاك الطاقة إلى انخفاض جودة الهواء. تكشف العلاقة السببية للفريق عن علاقة سببية أحادية الاتجاه من استثمارات التمويل الأخضر، وإجمالي الإنتاج، واستهلاك الطاقة والاستقرار السياسي إلى جودة الهواء، والعلاقة السببية ثنائية الاتجاه بين الجودة المؤسسية وجودة الهواء. وفقًا لهذه النتائج، فقد تبين أنه على المدى الطويل، تؤثر استثمارات التمويل الأخضر، والإنتاج الإجمالي، واستهلاك الطاقة، والاستقرار السياسي، والجودة المؤسسية على جودة الهواء. وبناءً على هذه النتائج، تم اقتراح الآثار المترتبة على السياسات.

In our days, having all the necessary literature and methods for the implementation of street lighting design, it is possible to propose sustainable solutions that offer benefits in energy saving, the environment and optimization of living conditions. However, so far, research has shown that studies either follow the Standards or are carried out empirically, taking into consideration certain parameters at a time rather than all the parameters concerning a street lighting design. The present work's aim is to elucidate the critical design parameters involved in road lighting analysis, covering both theoretical aspects of the design process and practical implementation in field applications, highlighting their importance in terms of energy savings and their contribution to sustainable development. The analysis concluded in a large number of parameters which form a lighting analysis. It was noted that many researchers tend to adopt an one-sided perspective on the subject by focusing on specific parameters within a single case category. This approach does not provide reliable results regarding the overall energy efficiency and savings of a system. Parameters such as energy indicators, adaptive lighting, road surface characteristics, mesopic vision, etc. require further investigation to explore efficient and sustainable solutions that prioritize both human well-being and environmental impact. Simultaneously, the frequent use of new technologies has led to their overuse, that sometimes has as a concequence the increase of energy consumption and operational cost rather than reducing it. It is also obvious that design loses its value compared with technology that continuously gains ground. At the moment, by having all the relevant information, it seems to be the time to proceed to a new holistic design approach, that combines all the necessary parameters that formulate a road lighting analysis. This approach aims to deliver more accurate results, contributing to a more efficient and sustainable urban environment. Contribution to science: A systematic scientific literature review on energy management and energy saving in road lighting is conducted, investigating parameters such as energy indicators, adaptive lighting, mesopic vision, road surface, design parameters, on-site elements and technology-equipment that constitute a road lighting study, identifying the lacking points and highlighting the areas for further research towards a more efficient, sustainable and environmentally friendly urban environment.

PurposeFirst, the current study contributes to the available debate by reinvestigating the impact of economic growth (EG), foreign direct investment (FDI), technological innovation (TI) and inflation (INF) on trade openness (TO). Second, the study tests the moderating role of institutional quality (INS) on the relationship among EG, FDI, TI and TO. Third, the study tests how TO contributes to EG efficiency.Design/methodology/approachThe study collects the data from the group of twenty (G20) economies for the period of 1998–2020. The study applied the Kao (1999), Pedroni (2001), and Palamuleni (2017) cointegration tests to test the long-run association between variables. The study applied fully modified least square (FMOLS) and dynamic least square (DOLS) models to test the hypotheses.FindingsFindings of the study showed the positive impact of EG, FDI and TI on TO, which becomes more positive in the presence of institutional quality. Results indicate that INS plays an enhancing role in the relationship between FDI and TO, EG and TO and TI and TO. The study showed a negative relationship between INF and TO, and institutional quality plays a buffering role in the relationship between INF and TO.Originality/valueFirst, the study reinvestigates the empirical association among EG, FDI, TI, INF and TO. Second, the study tests the moderating role of INS on the relationship between the proposed variables by developing an index of all the indicators of INS. Third, the study tests the contributions of TO in economic efficiency (ECE). The contributions of the present study will increase the available literature of TO and help the policy makers of G20 nations to suggest important policies to promote TO and ECE.