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This article has been withdrawn as it was published elsewhere and accidentally duplicated. The original article can be seen here: 10.1108/09615539810232880. When citing the article, please cite: A. Mezrhab, L. Bchir, (1998), “Radiation-natural convection interactions in partitioned cavities”, International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 8 Iss: 7, pp. 781 - 799.

The heat transfer by radiation and natural convection in a two‐dimensional, air‐filled square enclosure with a vertical partition of finite thickness and varying height was investigated numerically in the laminar regime. The horizontal end walls are assumed to be adiabatic, and the vertical walls are at different temperatures. Calculations are made by using a finite volume method and an efficient numerical procedure is introduced for calculating the view factors, with shadow effects included. The results indicate that the partition does not significantly modify the heat transfer rate through the cavity, especially at high Rayleigh numbers, provided that its height is less than 90 per cent of the cavity height. The effects of radiation on the velocity and the temperature fields and the overall heat transfer rates as a function of the widths of the vents, solid/fluid conductivity ratio and Rayleigh number are documented.

This paper presents a numerical investigation of the interaction of surfaces radiation with developing laminar free convective heat transfer in a divided vertical channel. The influence of the radiation on the heat transfer and on the air flow is studied for various sizes (width and length) of the plate.

The specifically developed numerical code is based on the utilization of the finite volume method. The SIMPLER algorithm for the pressure‐velocity coupling is adopted. The view factors are determined by using boundary elements to fit the surfaces, an algorithm solving the shadow effect and a Monte Carlo method for the numerical integrations.

Results obtained show that the radiation: plays a very important role on the paces of the isotherms, especially at Ra≥1,600; increases considerably the average wall Nusselt number; and increases the mass flow rate and the average channel Nusselt number at high Rayleigh numbers. The plate location has a significant effect on the heat transfer only in presence of the radiation exchange. The increase of both length and width of the plate causes a decrease of the heat transfer and the mass flow rate.

The use of the code is limited to the flow that is assumed to be incompressible, laminar and two dimensional. The radiative surfaces are assumed diffuse‐gray.

Natural convection in vertical channels formed by parallel plates has received significant attention because of its interest and importance in industrial applications. Some applications are solar collectors, fire research, electronic cooling, aeronautics, chemical apparatus, building constructions, nuclear engineering, etc.

In comparison to the most of the previous studies on natural convection in partitioned channels, the radiation exchange was neglected. This study takes into account the radiation exchange in a divided channel.

This paper describes an approach for the automatic calculation of view factors between surfaces of arbitrary shape, when taking into account possible screening effects due to intermediate surfaces.

The specifically developed numerical code is based on the utilization of boundary elements to fit the surfaces of an algorithm solving the shadow effect and on a Monte Carlo method for the numerical integrations.

The code has been tested for a set of geometrical configurations. It was clearly shown that it obtains good results in terms of accuracy and computing time. Its accuracy increases when the mesh of radiative surfaces is finer.

The use of the code is limited to opaque surfaces separated by an isothermal semi‐transparent medium which can be absorbent but not diffusing of the thermal radiation.

The study of the radiative exchanges between opaque surfaces with shadow effects due to intermediate surfaces may have concrete practical applications by using this code. Indeed, the code has been used for an industrial application, in order to evaluate view factors inside an enclosure, in the framework of studies concerned with the thermal comfort inside cars.

The originality of this paper lies in taking into account the surfaces of complex geometries by using a boundary elements approximation, the algorithm solving the shadow effect, based on the convexity of the quadrilateral in 2D or the polyhedron in 3D.

A detailed numerical study is conducted on the effect of surface radiation on laminar natural convection in a tall vertical cavity filled with air. The cavity is heated and cooled, through its two vertical walls, by a linear or uniform heat flux q(y) and by a constant cold temperature, respectively. The horizontal walls are considered adiabatic. The paper aims to discuss these issues.

The radiosity method is employed to calculate the net radiative heat exchanges between elementary surfaces, while the finite volume method is implemented to resolve the governing equations of the fluid flow.

For each heat flux q(y) (ascending, descending or uniform), the effect of the emissivity ε (0ε1) on the local, average and maximum temperatures of the heated wall is determined as a function of the average Rayleigh number Ra_m (103Ra_m6×104) and the cavity aspect ratio A (10A80). The effect of the coupling on the flow structures, convective and radiative heat transfers is also presented and analyzed. Overall, it is shown that surface radiation significantly reduces the local and average temperatures of the heated wall and therefore reduces the convective heat transfer between the active walls.

The studied configuration is of practical interest in several areas where overheating must be avoided. For this purpose, a simple design tool is developed to estimate the mean and the maximum temperatures of the hot wall in different operating conditions (Ra_m, A et ε).

The originality lies in the study of the interaction between surface radiation and natural convection in tall cavities submitted to a non-uniform heat flux and a constant cold temperature on the active walls. Also, the development of an original simplified calculation procedure for the hot wall temperatures.

This paper seeks to investigate the effect of a heat conducting vertical partition in an enclosure on natural convection heat transfer and fluid flow using the polynomial‐based differential quadrature (PDQ) method.

The PDQ method with the non‐uniform Chebyshev‐Gauss‐Lobatto grid point distribution given below is used to transform the governing equations into a set of algebraic equations. After numerical discretization, the resulting algebraic equations are solved by the successive over‐relaxation iteration method.

It is found that the average Nusselt number decreases towards a constant value as the partition is distanced from the hot wall towards the middle of the enclosure. Furthermore, with decreasing thermal conductivity ratio, the average Nusselt number first increases and passes a peak point and then begins to decrease. The average heat transfer rate exhibits little dependence on the width of the partition in the range taken into consideration in this study for the thickness of the partition.

This study offers more knowledge on natural convection in partitioned enclosures.

The purpose of this study was to investigate the impact of replacing two different fats on dyslipidemia, glycemic balance and adipose tissue redox status in obese rats.

Obesity was induced by feeding a high-mutton-fat diet during three months. An experimental group (n = 24) was divided into two groups that were fed during one month, 20 per cent of margarine or sardine oil. At Day 30, six rats from each group were sacrificed and the remaining rats were then subjected to a change in diet for one month: margarine was replaced by sardine oil and inversely, and then the rats were sacrificed. Three other groups (n = 6), each fed during two months, 20 per cent of margarine, sardine oil or mutton fat, served as controls.

Substitution of sardine oil by margarine compared to control sardine oil had increased triacylglycerols (TGs), glycosylated hemoglobin (HbA1c) and isoprostanes (IsoPs) values, but decreased thiobarbituric acid reactive substances (TBARS) and superoxide dismutase activity. Replacing margarine by sardine oil compared to control margarine reduced total cholesterol, TG, HbA1c, TBARS and IsoP contents but enhanced glutathione reductase and peroxidase activities. Nevertheless, comparing with the mutton fat, the two substitutions had improved glycemic and lipidic abnormalities and attenuated lipoperoxidation by enhancing enzymatic antioxidant defense. These favorable effects were better when margarine was replaced by sardine oil.

Substituting margarine with sardine oil seems to attenuate beneficial cardiometabolic risk markers associated to obesity and potentiate efficiency adipose tissue against the oxidative stress induced by the obesogenic diet.

This paper aims to provide a quantitative assessment of the broad economic effects of tax policy reform in the Kingdom of Saudi Arabia (KSA).

Using a dynamic computable general equilibrium (CGE) model of the KSA, three simulations are run. The first simulation is the baseline simulation, which generates growth paths of the Saudi economy in the absence of tax reform. In developing the baseline simulation, this study incorporates forecasts from the International Monetary Fund. The remaining simulations are policy simulations. A policy simulation deviates from the baseline simulation in response to a policy change. In the first policy simulation, this study introduces a value-added tax (VAT) that generates SAR 35bn. This study assumes budget neutrality with the additional tax revenue transferred to households via a lump sum payment. In the second policy simulation, this study introduces a corporate income tax that generates SAR 35bn. This study then calculates and compares the distortion these taxes introduce into the economy.

This study finds that although the introduction of new taxes increases government tax revenue, markets are distorted lowering efficiency and production. An introduction of VAT increases the cost of consumption relative to the cost of production. As a consequence, the real cost of labour increases lowering employment in the short run. Employment moves to the baseline, as wages adjust capital and real gross domestic product (GDP) is below base throughout the simulation period. The second simulation is an increase in the corporate tax rate with lowers the post-tax rates of return investors receive. This simulation shows that the negative impact on investment, capital and GDP is larger with the introduction of a corporate tax than with the VAT.

Literature focusing on tax policy reform in the Gulf Cooperation Council and, specifically, Saudi Arabia is limited. This paper contributes to the literature by focusing on the following: understanding the impact and mechanisms through which changes in taxation impact the economy more generally; understanding the potential harm caused to allocative efficiency and production due to taxes; and ways in which fiscal reform might complement other reforms such as efforts to diversify the economy, labour market and energy price reforms. This improves the information base available to policymakers charged with designing an optimal tax system that meets all future requirements of a country such as the KSA.

The authors developed and applied a CGE model for the KSA to analyse the impact of VAT and corporate tax on the Saudi economy. To the best of the authors’ knowledge, there are no recent CGE models for Saudi Arabia that have been used for tax policy or quantifying the potential harm to the economy when new taxes are introduced.

The purpose of this paper was to develop a loaf bread enriched with naranjilla (lulo) fruit (shells, seeds and pulp) and determine the technical quality, sensory acceptability and bioavailability (by in vitro digestion) of antioxidant components.

Loaf bread was prepared by using a no-time bread-making process. The crumb moisture, specific volume, crust and crumb color, texture profile analysis, analysis of the crumbs' alveoli, sensory evaluation, in vitro simulation of gastrointestinal digestion and antioxidant capacity were determined. Data were analyzed with one-way ANOVA (α = 0.05).

The specific volume was reduced by 21% (4.62 cm3/g, p < 0.0001), and the hardness was increased by 70% (2.9 N, p < 0.0001). Enrichment of the bread with naranjilla fruit (NF) contributes a yellowish coloration to the bread, which was very well accepted by the consumers and could be considered a natural colorant alternative. Moreover, the sensory evaluation indicated that the analyzed attributes (appearance, color, odor, taste, firmness and overall quality) of the naranjilla bread presented scores higher than 6.5 of 9 points hedonic scale. Naranjilla in the bread formulation had good acceptability by consumers. Naranjilla-enriched bread had an increase in total phenolic (TP)compounds and total carotenoids. In the product without digestion, naranjilla bread increased 1.7 times for TP, 50 times for CT and 1.3 times for TEAC, compared to the control bread (p < 0.0001). The percentage of bioaccessibility for fresh bread without digestion was 39.2 and 53.9% for the control and naranjilla bread, respectively. The addition of NF contributes to a higher TP compounds content and favors its bioavailability.

For bread production, fruits that do not meet the quality standards to be consumed as a natural fruit can be used. In this way, these fruits can contribute as a potential use to reduce agro-industrial waste and as a natural colorant.

Naranjilla is a native fruit from the subtropical Andean regions, which has high ascorbic acid concentrations, making it a fruit rich in antioxidants. Naranjilla-enriched bread contributes with beneficial compounds for the consumer.

The purpose of this study was to characterize fruit properties of pomegranate cultivars grown in South Africa in order to provide information to assist in selecting cultivars for food and industrial purposes, as well as to optimize postharvest handling and processing.

The physical, textural and chemical properties as well as volatile profile and free radical scavenging capacity of eight cultivars (cvs “Acco”, “Arakta”, “Bhagwa”, “Ganesh”, “Herskawitz,” “Molla de Elche”, “Ruby”, and “Wonderful”) were quantified to demonstrate the diversity among the characters of the commercially grown cultivars.

Statistically significant differences were found between cultivars for most of the evaluated characters, primarily highlighting the genetic diversity among the cultivars. The classification of fruit cultivars based on quality traits (such as size, texture, colour, soluble solids, acidity, juiciness and phenolics) showed the great potential of the cultivars for processing and fresh market. The relationship among these quality traits was analysed by principal component analysis (PCA) resulting in the separation of the investigated cultivars into two groups (cluster 1=Ruby, Arakta and Ganesh; Class 2=Bhagwa, Acco and Herskawitz) and two ungrouped cultivars (Molla de Elche and Wonderful). Specific understanding about quality traits of each cultivar was established using the correlation coefficients obtained.

This study provides valuable fundamental information that can be useful for commercial and industrial purposes, as well as the development of optimal postharvest handling and processing parameters for the investigated South African grown pomegranate cultivars.