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This paper describes a study concerning the numerical simulation of a sonic helium jet through a transverse nozzle in a flat plate exhausting normally into a supersonic air flow. Three‐dimensional Reynolds‐averaged Navier—Stokes equations coupled with the modified Baldwin‐Lomax algebraic turbulence model and relevant species equations are solved by using a finite‐volume upwind scheme. In this approach, Roe’s flux function, explicit multi‐stage integration and multi‐block procedure are applied to achieve the steady state solution efficiently. The Roe’s flux function is modified to suit the simulation of helium‐air mixing. The comparison between two‐dimensional calculated results with experimental data of surface pressure shows good agreement. The results of three‐dimensional computations for square, circular and rectangular jets are presented, and the essential flow features including induced shocks, upstream separations, and downstream primary and secondary vortices are adequately simulated.

Natural convection in differentially heated enclosures has been extensively investigated due to its importance in many industrial applications and has been used as a benchmark solution for testing numerical schemes. However, most of the published works considered uniform heating and cooling of the vertical boundaries. This paper aims to examine non-uniform heating and cooling of the mentioned boundaries. The mentioned case is very common in many electronic cooling devices, thermal storage systems, energy managements in buildings, material processing, etc.

Four cases are considered, the left-hand wall’s temperature linearly decreases along the wall, while the right-hand wall’s temperature is kept at a constant, cold temperature. In the second case, the left-hand wall’s temperature linearly increases along the wall, while the right-hand wall’s temperature is kept a constant, cold temperature. The third case, the left-hand wall’s temperature linearly decreases along the wall, while the right-hand wall’s temperature linearly increases along the wall. In the fourth case, the left-hand and the right-hand walls’ temperatures decrease along the wall, symmetry condition. Hence, four scenarios of natural convection in enclosures were covered.

It has been found that the average Nusselt number of the mentioned cases is less than the average Nusselt number of the uniformly heated and cooled enclosure, which reflects the physics of the problem. The work quantifies the deficiency in the rate of the heat transfer. Interestingly one of the mentioned cases showed two counter-rotating horizontal circulations. Such a flow structure can be considered for passively, highly controlled mechanism for species mixing processes application.

Previous works assumed that the vertical boundary is subjected to a constant temperature or to a sinusoidal varying temperature. The subject of the work is to examine the effect of non-uniformly heating and/or cooling vertical boundaries on the rate of heat transfer and flow structure for natural convection in a square enclosure. The temperature either linearly increases or decreases along the vertical coordinate at the boundary. Four scenarios are explored.

Poor post-harvest handling practices by seaweed farmers are a key issue in seaweed value chains, contributing to low-quality seaweed being supplied to processors. To address this, a range of advanced drying technologies and methods have been developed, yet uptake by farmers remains low. This study examines factors affecting drying technology uptake by seaweed farmers to identify opportunities to incentivise improved drying practices.

This study draws on a quantitative survey of 273 seaweed farmers in two villages in South Sulawesi, 16 months of ethnographic fieldwork and 166 semi-structured interviews.

Farmers engage in limited adoption of improved drying technologies and practices as they don't receive higher prices for higher quality products, instead aiming to meet only the minimum acceptable standards to avoid a price discount or rejection of their product. Technologies and techniques that have been adopted are often used in ways that differ from their original purpose, such as to reduce drying times and labour input, rather than to produce products of low moisture and dirt contents. Similarly, local traders mix high- and low-quality seaweed in order to supply warehouses with seaweed which on average meets minimum quality standards.

This study reveals that improved drying practices are unlikely to be adopted unless incentivised by more targeted price-grade differentials.

Competition will affect the structure of an industry and the structure will, in turn, affect the behaviour of the firms involved. Two of the most important characteristics of the online information industry are the diversity of hosts and the range of databases offered by each one. The latter is a significant factor in searchers' choices of databases and consequently encourages hosts to compete by acquiring additional databases. This type of non‐price competition plays a key role as it is difficult to make accurate comparisons of the costs of using different hosts. Parallels are drawn with other industries in which competition is, or was, expressed chiefly in the form of capacity. The structure of one sector of the online information industry was investigated by applying Q‐analysis to data on medical databases and hosts. Changes over a three‐year period are identified and are interpreted using concepts derived from ecological niche theory. Finally, the question of what would constitute an optimum structure is considered and it is argued on the basis of an economic theory originally propounded by H. Hotelling that free competition would be unlikely to produce optimal results.

An aerothermodynamic design code for axisymmetric projectiles has been developed using a viscous‐inviscid interaction scheme. Separate solution procedures for the inviscid and the viscous (boundary layer) fluid dynamic equations are coupled by an iterative solution procedure. Non‐equilibrium, equilibrium and perfect gas boundary layer equations are included. The non‐equilibrium gas boundary layer equations assume a binary mixture (two species; atoms and molecules) of chemically reacting perfect gases. Conservation equations for each species include finite reaction rates applicable to high temperature air. The equilibrium gas boundary layer equations assume infinite rate reactions, while the perfect gas equations assume no chemical reactions. Projectile near‐wall and surface flow profiles (velocity, pressure, density, temperature and heat transfer) representing converged solutions to both the inviscid and viscous equations can be obtained in less than two minutes on minicomputers. A technique for computing local reverse flow regions is included. Computations for yawed projectiles are accomplished using a coordinate system transformation technique that is valid for small angle‐of‐attack. Computed surface pressure, heat transfer rates and aerodynamic forces and moments for 1.25 &le Mach No. &le 10.5 are compared to wind tunnel and free flight measurements on flat plate, blunt‐cone, and projectile geometries such as a cone‐cylinder‐flare.

The interaction of two species can be considered to be either mutually competitive, the “co‐predator” case, or dominated by one species, the “predator‐prey” model. The study of stochastic versions of these models has been impeded by the occurrence of nonlinear expressions in the characterization of the resulting probability structure. Generating function methods are used to study the bivariate and conditional probability distributions and their moments. The results are illustrated using a Laplace transform technique for obtaining numerical values. These methods can be used in the development of ecological prediction techniques and can be extended easily to the bivariate logistic model.

Purpose – This chapter contributes to comparative biopolitics and reviews primatological literature, especially about our nearest relatives, the Great Apes.

Design/methodology/approach – Biopolitics in this chapter means evolutionarily informed political science, with emphasis on power relations. I review the literature on intrasexual and intersexual dominance interactions among individuals and competitive and/or agonistic interactions among groups in the Great Apes (Hominidae, formerly Pongidae): orangutan (Pongo with two species and three subspecies), gorilla (Gorilla with four subspecies), bonobo (Pan paniscus), and common chimpanzee (Pan troglodytes with four subspecies). In the final section I present some (speculative) thoughts on Pan prior or the modern human ancestor.

Findings – Not only Man is a political animal.

Originality/value – Impartial, objective, and as complete as possible review of the literature for the students of (comparative) politics, ethology, and psychology.

The characteristics of fluid motions in micro-channel are strong fluid-wall surface interactions, high surface to volume ratio, extremely low Reynolds number laminar flow, surface roughness and wall surface or zeta potential. Due to zeta potential, an electrical double layer (EDL) is formed in the vicinity of the wall surface, namely, the stern layer (layer of immobile ions) and diffuse layer (layer of mobile ions). Hence, its competent designs demand more efficient micro-scale mixing mechanisms. This paper aims to therefore carry out numerical investigations of electro osmotic flow and mixing in a constricted microchannel by modifying the existing immersed boundary method.

The numerical solution of electro-osmotic flow is obtained by linking Navier–Stokes equation with Poisson and Nernst–Planck equation for electric field and transportation of ion, respectively. Fluids with different concentrations enter the microchannel and its mixing along its way is simulated by solving the governing equation specified for the concentration field. Both the electro-osmotic effects and channel constriction constitute a hybrid mixing technique, a combination of passive and active methods. In microchannels, the chief factors affecting the mixing efficiency were studied efficiently from results obtained numerically.

The results indicate that the mixing efficiency is influenced with a change in zeta potential (ζ), number of triangular obstacles, EDL thickness (λ). Mixing efficiency decreases with an increment in external electric field strength (Ex), Peclet number (Pe) and Reynolds number (Re). Mixing efficiency is increased from 28.2 to 50.2% with an increase in the number of triangular obstacles from 1 to 5. As the value of Re and Pe is decreased, the overall percentage increase in the mixing efficiency is 56.4% for the case of a mixing micro-channel constricted with five triangular obstacles. It is also vivid that as the EDL overlaps in the micro-channel, the mixing efficiency is 52.7% for the given zeta potential, Re and Pe values. The findings of this study may be useful in biomedical, biotechnological, drug delivery applications, cooling of microchips and deoxyribonucleic acid hybridization.

The process of mixing in microchannels is widely studied due to its application in various microfluidic devices like micro electromechanical systems and lab-on-a-chip devices. Hence, its competent designs demand more efficient micro-scale mixing mechanisms. The present study carries out numerical investigations by modifying the existing immersed boundary method, on pressure-driven electro osmotic flow and mixing in a constricted microchannel using the varied number of triangular obstacles by using a modified immersed boundary method. In microchannels, the theory of EDL combined with pressure-driven flow elucidates the electro-osmotic flow.

The purpose of this paper is to propose a conceptualization of supply chain vs supply chain competition using the ecological niche approach. It suggests a probabilistic methodology for evaluating competition from time series data, using overlap in the utilization of services provided by critical providers as a source of competition.

Literature on ecological niche theory and competition is explored and given the uncertainty that surrounds the operation and management of supply chains, a probabilistic approach to the analysis of supply chain vs supply chain competition (via the Bayesian inference) is advocated. Simulated data are used to illustrate the methodology.

Should an area of overlap be identified, ecological niche theory provides a sensible approach to identifying the nature and extent of competition between supply chains. Applicability of the methodology is not limited to supply chain vs supply chain competition.

The data used for the analysis of competition between supply chains are computer generated and use a single niche dimension. Although this was done to merely test/validate the proposed model, the approach is somewhat oversimplified. However, the model is readily extendable to multiple niche dimensions.

The proposed approach offers a simple and straight‐forward method of estimating competition in general, and supply chains vs supply chain competition in particular. Attempts at using the niche theory of competition in this context are so far inconspicuous. Hence, approaching competition in this way contributes to furthering our understanding of competitive interaction especially in supply chains, whose prospect is yet to be pointed out in literature.

The dynamics of a transitional propane jet diffusion flame with a fuel‐jet velocity of 2.2 m/s has been studied using an implicit, third‐order‐accurate, upwind numerical scheme. The large‐scale vortices outside the flame surface and the small‐scale ones inside were simulated simultaneously, and their interactions with the flame surface were investigated. Numerical experiments were conducted to gain insight into the influence of buoyancy and shear‐layer forcing on the development of the outer and inner vortices. In the presence of buoyancy forces, the outer vortices developed as part of the solution, and the vortex‐crossing frequency was approximately 15 Hz. The inner structures were manifested from a weak perturbation the vorticity that was introduced at the nozzle exit, and, at 185 Hz, these vortices were found to travel farther downstream. It was also found that the inner vortices do not play a role in the formation of the outer vortices, and vice versa. However, the growth of the inner vortices in the downstream locations is strongly influenced by the slowly moving outer vortices.