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Free and moving boundary problems require the simultaneous solution of unknown field variables and the boundaries of the domains on which these variables are defined. There are many technologically important processes that lead to moving boundary problems associated with fluid surfaces and solid‐fluid boundaries. These include crystal growth, metal alloy and glass solidification, melting and flame propagation. The directional solidification of semi‐conductor crystals by the Bridgman—Stockbarger method^1,2 is a typical example of such a complex process. A numerical model of this growth method must solve the appropriate heat, mass and momentum transfer equations and determine the location of the melt—solid interface. In this work, a Chebyshev pseudospectral collocation method is adapted to the problem of directional solidification. Implementation involves a solution algorithm that combines domain decomposition, a finite‐difference preconditioned conjugate minimum residual method and a Picard type iterative scheme.

In this chapter we discuss the dynamics of convergence-divergence between organic and non-organic farming systems. We are specifically interested in how and in what ways organic systems emerge into a new system that synthesizes the diverse qualities of competing systems. Or, will these systems continue to diverge because of their path dependencies and contradictory, unresolvable logics? Alternatively, are we confronted with conversion? Following a discussion of the origin of organic agriculture and the IFOAM Principles, we explore differentiation of two agricultural paradigms that was developed more than 20 years ago before the rise of GMOs. This comparison identifies the key features of both systems and a first interpretation on the potential of convergence-divergence. Third, we take a macro-look at agro-food chain that offers insights on the convergence-divergence potential in the context of global, economic, market, political, and societal dynamics. Fourth, we discuss convergence-divergence at the production level comparing the four agricultural systems. Finally, we reflect and assess on the explanatory potential of our study for the future development of organic and non-organic agriculture/farming. We conclude that there is more evidence for conversion than for convergence.

The quality of crystals grown in space can be diversely affected by the melt flows induced by g‐jitter associated with a space vehicle. This paper presents a full three‐dimensional (3D) transient finite element analysis of the complex fluid flow and heat and mass transfer phenomena in a simplified Bridgman crystal growth configuration under the influence of g‐jitter perturbations and magnetic fields.

The model development is based on the Galerkin finite element solution of the magnetohydrodynamic governing equations describing the thermal convection and heat and mass transfer in the melt. A physics‐based re‐numbering algorithm is used to make the formidable 3D simulations computationally feasible. Simulations are made using steady microgravity, synthetic and real g‐jitter data taken during a space flight.

Numerical results show that g‐jitter drives a complex, 3D, time dependent thermal convection and that velocity spikes in response to real g‐jitter disturbances in space flights, resulting in irregular solute concentration distributions. An applied magnetic field provides an effective means to suppress the deleterious convection effects caused by g‐jitter. Based on the simulations with applied magnetic fields of various strengths and orientations, the magnetic field aligned with the thermal gradient provides an optimal damping effect, and the stronger magnetic field is more effective in suppressing the g‐jitter induced convection. While the convective flows and solute transport are complex and truly 3D, those in the symmetry plane parallel to the direction of g‐jitter are essentially two‐dimensional (2D), which may be approximated well by the widely used 2D models.

The physics‐based re‐numbering algorithm has made possible the large scale finite element computations for 3D g‐jitter flows in a magnetic field. The results indicate that an applied magnetic field can be effective in suppressing the g‐jitter driven flows and thus enhance the quality of crystals grown in space.

The purpose of this paper is to investigate numerically thermal convection heat transfer in closed square and cubical cavities with local energy sources of various geometric shapes.

The analyzed regions are square and cubical cavities with two isothermally cold opposite vertical walls, whereas other walls are adiabatic. A local energy element of rectangular, trapezoidal or triangular shape is placed on the lower surface of the cabinet. The lattice Boltzmann technique has been used as the main method for the problem solution in two-dimensional (2D) and three-dimensional (3D) formulations, whereas the finite difference technique with non-primitive parameters such as stream function and vorticity has been also used.

The velocity and temperature fields for a huge range of Rayleigh number 104–106, as well as for various geometry shapes of the heater have been studied. A comparative analysis of the results obtained on the basis of two numerical techniques for 2D and 3D formulations has been performed. The dependences of the energy transfer strength in the region on the shape of energy source and Rayleigh number have been established. It has been revealed that the triangular shape of the energy source corresponds to the maximum values of the velocity vector and temperature within the cavity, and the rectangular shape corresponds to the minimum values of these mentioned variables. With the growth of the Rayleigh number, the difference in the values of these mentioned variables for rectangular and triangular shapes of heaters also increases.

The originality of this work is to scrutinize the lattice Boltzmann method and finite difference method for the problem of natural convection in 2D and 3D closed chambers with a local heated element.

The purpose of this paper was to analyse the demographic, crop choice, institutional and environmental factors that will influence the vegetable growers in Bono and Ahafo regions of Ghana to produce organic vegetables. The study also assessed the knowledge level of vegetable growers on organic certification processes.

Primary data were collected with the help of a structured questionnaire from 120 vegetable growers via a multistage sampling technique. The Heckman selection model was used to analyse the factors that influence farmers' willingness to adopt organic production as well as the intensity of adoption.

In this study, pepper (Capsicum spp) production, residential status, knowledge of organic certification processes, perceived negative environmental effect of conventional farming on the soil, and climate change positively influenced willingness to produce organic vegetables. Likewise, pepper production perceived negative environmental effect of conventional farming on the soil positively influenced the intensity of adoption. Household headship status, garden egg (Solanum integrifolium) production, perceived knowledge on grading and standards of vegetables, as well as the perception that only pesticides can be used to control vegetable pests negatively influenced the willingness to produce organic vegetables however perceived expertise of the farmer on grades and standards influenced intensity of adoption negatively.

In Ghana, even though most vegetable farmers do not have the requisite knowledge in the safe handling of pesticides, usage is widespread. Subsequent to this, is a health risk to farmers, consumers and the environment. As a result, there is a growing awareness that organic agriculture has a role to play in addressing problems associated with agrochemical use and over usage. However, most studies are consumer oriented with limited empirical research on the willingness to produce organics by farmers.

The peer review history for this article is available at: https://publons.com/publon/10.1108/IJSE-12-2019-0723

The purpose of this paper is to introduce a novel approach based on the high-order matrix derivative of the Bernstein basis and collocation method and its employment to solve an interesting and ill-posed model in the heat conduction problems, homogeneous backward heat conduction problem (BHCP).

By using the properties of the Bernstein polynomials the problems are reduced to an ill-conditioned linear system of equations. To overcome the unstability of the standard methods for solving the system of equations an efficient technique based on the Tikhonov regularization technique with GCV function method is used for solving the ill-condition system.

The presented numerical results through table and figures demonstrate the validity and applicability and accuracy of the technique.

A novel method based on the high-order matrix derivative of the Bernstein basis and collocation method is developed and well-used to obtain the numerical solutions of an interesting and ill-posed model in heat conduction problems, homogeneous BHCP with high accuracy.

This paper aims to perform a meta‐analysis of the literature comparing the environmental impacts of organic and conventional farming and linking these to differences in management practises. The studied environmental impacts are related to land use efficiency, organic matter content in the soil, nitrate and phosphate leaching to the water system, greenhouse gas emissions and biodiversity.

The theoretic framework uses the driver‐state‐response framework and literature data were analysed using meta‐analysis methodology. Meta‐analysis is the statistical analysis of multiple study results. Data were obtained by screening peer reviewed literature.

From the paper's meta‐analysis it can conclude that soils in organic farming systems have on average a higher content of organic matter. It can also conclude that organic farming contributes positively to agro‐biodiversity (breeds used by the farmers) and natural biodiversity (wild life). Concerning the impact of the organic farming system on nitrate and phosphorous leaching and greenhouse gas emissions the result of the analysis is not that straightforward. When expressed per production area organic farming scores better than conventional farming for these items. However, given the lower land use efficiency of organic farming in developed countries, this positive effect expressed per unit product is less pronounced or not present at all.

Given the recent growth of organic farming and the general perception that organic farming is more environment friendly than its conventional counterpart, it is interesting to explore whether it meets the alleged benefits. By combining several studies in one analysis, the technique of meta‐analysis is powerful and may allow the generation of more nuanced findings and the generalisation of those findings.

The purpose of this paper is to consider the global activities, highlighting the UK, concerned with farm assurance schemes and associated food labelling seeking to identify their contribution towards improving primary production standards.

A desk study focusing on published literature and historical documentation.

The majority of primary production standards are based upon codes of good practice with only tenuous links between the standards and the required environmental outcomes. Owing to the difficulties of comparing like with like here is little conclusive evidence that such standards are producing environmental benefits.

If it depends on assurance schemes to improve farming practices then a European‐wide standard is required that is not compromised by variations in national laws and codes of practice.

This review is of academic value and of value to those working to improve primary production standards. It presents arguments for introducing environmental outcome based measures into the UK assurance schemes.

Many jurisdictions fine illegal cartels using penalty guidelines that presume an arbitrary 10% overcharge. This article surveys more than 700 published economic studies and judicial decisions that contain 2,041 quantitative estimates of overcharges of hard-core cartels. The primary findings are: (1) the median average long-run overcharge for all types of cartels over all time periods is 23.0%; (2) the mean average is at least 49%; (3) overcharges reached their zenith in 1891–1945 and have trended downward ever since; (4) 6% of the cartel episodes are zero; (5) median overcharges of international-membership cartels are 38% higher than those of domestic cartels; (6) convicted cartels are on average 19% more effective at raising prices as unpunished cartels; (7) bid-rigging conduct displays 25% lower markups than price-fixing cartels; (8) contemporary cartels targeted by class actions have higher overcharges; and (9) when cartels operate at peak effectiveness, price changes are 60–80% higher than the whole episode. Historical penalty guidelines aimed at optimally deterring cartels are likely to be too low.

The purpose of this paper is as follows: to significantly reduce the computation time (by a factor of 1,000 and more) compared to known numerical techniques for real-world problems with complex interfaces; and to simplify the solution by using trivial unfitted Cartesian meshes (no need in complicated mesh generators for complex geometry).

This study extends the recently developed optimal local truncation error method (OLTEM) for the Poisson equation with constant coefficients to a much more general case of discontinuous coefficients that can be applied to domains with different material properties (e.g. different inclusions, multi-material structural components, etc.). This study develops OLTEM using compact 9-point and 25-point stencils that are similar to those for linear and quadratic finite elements. In contrast to finite elements and other known numerical techniques for interface problems with conformed and unfitted meshes, OLTEM with 9-point and 25-point stencils and unfitted Cartesian meshes provides the 3-rd and 11-th order of accuracy for irregular interfaces, respectively; i.e. a huge increase in accuracy by eight orders for the new 'quadratic' elements compared to known techniques at similar computational costs. There are no unknowns on interfaces between different materials; the structure of the global discrete system is the same for homogeneous and heterogeneous materials (the difference in the values of the stencil coefficients). The calculation of the unknown stencil coefficients is based on the minimization of the local truncation error of the stencil equations and yields the optimal order of accuracy of OLTEM at a given stencil width. The numerical results with irregular interfaces show that at the same number of degrees of freedom, OLTEM with the 9-points stencils is even more accurate than the 4-th order finite elements; OLTEM with the 25-points stencils is much more accurate than the 7-th order finite elements with much wider stencils and conformed meshes.

The significant increase in accuracy for OLTEM by one order for 'linear' elements and by 8 orders for 'quadratic' elements compared to that for known techniques. This will lead to a huge reduction in the computation time for the problems with complex irregular interfaces. The use of trivial unfitted Cartesian meshes significantly simplifies the solution and reduces the time for the data preparation (no need in complicated mesh generators for complex geometry).

It has been never seen in the literature such a huge increase in accuracy for the proposed technique compared to existing methods. Due to a high accuracy, the proposed technique will allow the direct solution of multiscale problems without the scale separation.