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The global economy is facing a steep challenge from volatility, risk and uncertainty associated with climate change, pandemics, regional conflicts and trade wars which are unprecedented and overlapping. These crises are leading to macro- and microeconomic imbalances. The immediate effects like rising inflation, shortage of energy and fertiliser, food insecurity, loss of jobs and poverty are looming large, leading to existential threat. It is evident that decades of progress are at risk and pursuing sustainable development goals (SDGs) requires dedicated and customised efforts by the governments and other relevant actors, especially in the low- and middle-income countries (LMICS). The concept of circular economy is considered to bring a paradigm shift by reducing the dependence on natural resource extraction and decoupling economic growth from use of natural resources. Bioeconomy is another emerging field which deals with the use of renewable biological resources such as biomass to produce renewable biofuels, bioproducts, and biopower for economic, environmental and social benefits. Circular bioeconomy (CBE) lies at the intersection and is defined as the production of recoverable biological (waste) resources and the conversion of these resources into high-value-added products, such as food, feed, bio-based products and bioenergy. It has been estimated that the economic opportunity for the sector to complement or even substitute conventional ones is estimated to be USD 7.7 trillion by 2030 for food and feed waste products, and energy. CBE is perceived as a pathway for development and has the potential to target different SDGs directly like 6, 7 and 12 and SDGs 2, 3, 11, 12, 13 and 15 indirectly. This study explores the linkages of CBE with the SDG goals and provides recommendations to stimulate the sector.

Studies a two‐dimensional natural convection in a porous, square cavity using a regular asymptotic development in powers of the Rayleigh number. Carries the approximation through to the 34th order. Analyses convergence of the resulting series for the Nusselt number in both monocellular and multicellular cases, providing insight in the validity regions of the power series.

Manufacturing companies today are part of a dynamic, globalized system of production and consumption. Globally dividing labor is now the predominant way of organizing business, but it is clear that the resource demands of linear supply chains have created vulnerability and harm in the system and beyond. The authors draw inspiration from ecology to explore the role of manufacturers in the transition from linear to circular supply chains. Borrowing the adaptive cycle model, originally developed to describe dynamic ecological systems, they employ case examples to illustrate the ways that supply chain management is being reimagined in the shift to a circular economy. This conceptualization uses the adaptive cycle to consider the transition from linear to circular supply chains as part of broader systems change, and the opportunities for manufacturers to play a transformative role in shaping a sustainable future.

Petroleum hydrocarbons are naturally occurring flammable fossil fuels used as conventional energy sources. It has carcinogenic, mutagenic properties and is considered a hazardous pollutant. Soil contaminated with petroleum hydrocarbons adversely affects the properties of soil. This paper aim to remove pollutants from the environment is an urgent need of the hour to maintain the proper functioning of soil ecosystems.

The ability of micro-organisms to degrade petroleum hydrocarbons makes it possible to use these microorganisms to clean the environment from petroleum pollution. For preparing this review, research papers and review articles related to petroleum hydrocarbons degradation by micro-organisms were collected from journals and various search engines.

Various physical and chemical methods are used for remediation of petroleum hydrocarbons contaminants. However, these methods have several disadvantages. This paper will discuss a novel understanding of petroleum hydrocarbons degradation and how micro-organisms help in petroleum-contaminated soil restoration. Bioremediation is recognized as the most environment-friendly technique for remediation. The research studies demonstrated that bacterial consortium have high biodegradation rate of petroleum hydrocarbons ranging from 83% to 89%.

Proper management of petroleum hydrocarbons pollutants from the environment is necessary because of their toxicity effects on human and environmental health.

This paper discussed novel mechanisms adopted by bacteria for biodegradation of petroleum hydrocarbons, aerobic and anaerobic biodegradation pathways, genes and enzymes involved in petroleum hydrocarbons biodegradation.

The paper aims to assess the potential of aircraft operation from city centres to achieve shortened travel times and the involved aircraft design process.

The paper describes the methodical approach and iterative procedure of the design process. An assessment of potential technologies is conducted to provide the required enhancements to fulfil the constraints following an inner-city operation. Operational procedures were analysed to reduce the noise propagation through flight path optimization. Furthermore, a ground-based assisted take-off system was conceived to lower required take-off field length and to prevent engine sizing just for the take-off case. Cabin design optimization for a fast turnaround has been conducted to ensure a wide utilization spectrum. The results prove the feasibility of an aircraft developed for inner city operation.

A detailed concept for a 60-passenger single aisle aircraft is proposed for an Entry-Into-Service year 2040 with a design range of 1,500 nautical miles for a load factor of 90 per cent. Although the design for Short Take-off and Landing and low noise operation had to be traded partly with cruise efficiency, a noteworthy reduction in fuel burn per passenger and nautical mile could be achieved against current aircraft.

The findings will contribute to the evaluation of the feasibility and impact of the Flightpath 2050 goal of a 4-h door-to-door by providing a feasible but ambitious example. Furthermore, it highlights possible bottlenecks and problems faced when realizing this goal.

The paper draws its value from the consideration of the overall sizing effects at aircraft level and from a holistic view on an inner-city airport/aircraft concept design for a 4-h door-to-door goal.

The purpose of this study is to examine theoretically the axisymmetric flow of a steady free-surface jet emerging from a tube for high inertia flow and moderate surface tension effect.

The method of matched asymptotic expansion is used to explore the rich dynamics near the exit where a stress singularity occurs. A boundary layer approach is also proposed to capture the flow further downstream where the free surface layer has grown significantly.

The jet is found to always contract near the tube exit. In contrast to existing numerical studies, the author explores the strength of upstream influence and the flow in the wall layer, resulting from jet contraction. This influence becomes particularly evident from the nonlinear pressure dependence on the upstream distance, as well as the pressure undershoot and overshoot at the exit for weak and strong gravity levels, respectively. The approach is validated against existing experimental and numerical data for the jet profile and centerline velocity where good agreement is obtained. Far from the exit, the author shows how the solution in the diffusive region can be matched to the inviscid far solution, providing the desired appropriate initial condition for the inviscid far flow solution. The location, at which the velocity becomes uniform across the jet, depends strongly on the gravity level and exhibits a non-monotonic behavior with respect to gravity and applied pressure gradient. The author finds that under weak gravity, surface tension has little influence on the final jet radius. The work is a crucial supplement to the existing numerical literature.

Given the presence of the stress singularity at the exit, the work constitutes a superior alternative to a computational approach where the singularity is typically and inaccurately smoothed over. In contrast, in the present study, the singularity is entirely circumvented. Moreover, the flow details are better elucidated, and the various scales involved in different regions are better identified.

The purpose of the paper is to numerically simulate steady‐state thermo‐solutal convection in rectangular cavities with different aspect ratios, subject to horizontal temperature and concentration gradients, and validate the results against numerical and experimental data available from literature.

The fully explicit Artificial Compressibility (AC) version of the Characteristic Based Split (CBS) scheme is adopted to solve double diffusion (DD) problems. A stabilization analysis is carried out to efficiently solve the problems considered in the present work. The thermal and solutal buoyancy forces acting on the fluid have been taken into account in case of aiding and opposing flow conditions.

The stability limits derived by the authors for the thermo‐solutal convection assume a fundamental role to efficiently solve the DD problems considered. In the cases characterized by higher Rayleigh number the convergent solution is obtained only by employing the new stability conditions. The efficient matrix free procedure employed is a powerful tool to study complex DD problems.

In this paper, the authors extend the stabilization analysis for the AC‐CBS scheme to the solution of DD, fundamental to efficiently solve the present problems, and apply the present fully explicit matrix free scheme, based on finite elements, to the solution of DD natural convection in cavities.