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The purpose of this paper is to investigate numerically the influence of variable fluid viscosity on thermal characteristics of plate heat exchangers for counter‐flow and steady‐state conditions.

The approach to fulfill the purpose of the paper is to derive the one‐dimensional energy balance equations for the cold and hot streams in the adjacent channels of a plate heat exchange composed of four corrugated plates. A finite difference method has been used to calculate the temperature distribution and thermal performance of the exchanger. Water is used as the hot liquid being cooled in the side channels, while a number of working fluids whose viscosity variation versus temperature is more severe were used as the cold fluid being heated in the central channel.

The program is run for a combination of working fluids such as water‐water, water‐isooctane, water‐benzene, water‐glycerin and water‐gasoline. The temperature distributions of both streams have been plotted along the flow channel for all the above combination of working fluids. The overall heat transfer coefficients have also been plotted against both cold and hot fluid temperatures. It is found that the overall heat transfer coefficient varies linearly with respect to either cold or hot fluid temperature within the temperature ranges applied in the paper. The exchanger effectiveness is not significantly affected when either the temperature dependent viscosity is applied or the nature of cold liquid is changed.

This paper contains a new method of numerical solution of energy balance equations for the thermal control volumes bounded by two plates. A comparison of the calculated results with documented experimental results validates the numerical method.

The purpose of this paper is to predict the plate heat exchanger performance when axial conduction in plates and in flow channels are present and fluids' viscosities are temperature dependent.

The approach to achieve the objective of the paper is deriving the governing equations and developing a computer program based on finite differences to solve them. The governing equations become dimensionless defining reference values and then discretized using FTBCS and FTCS methods. To solve the governing equations, the flow channel is divided into small elements in axial direction. Physical properties are constant for each element, while viscosity changes from one element to another one.

The effect of axial conduction in plates as well as in flow channels on temperature distributions, are studied individually and simultaneously. The program is run under four different conditions, namely: no axial conduction, axial conduction in the plates and in the flow channels, axial conduction in the plates only, and axial conduction in the flow channels only.In all the above cases, temperature distributions are achieved and characteristic curves are plotted. The numerical results are validated by comparing them with those published in an established reference carried out ignoring the effect of axial conduction, using the same plate geometry and flow details.

This paper gives valuable information and offers practical help to plate heat exchanger design engineer in order to choose the proper material for the plates as well as the right service and product fluids.

The purpose of this paper is to predict the global solar radiation intensity in areas where meteorological stations do not exist and information on solar radiation cannot be obtained experimentally.

The approach to achieve the objective of the paper is developing multiple regression relations between the global solar radiation intensity (the dependent variable) and geographical, geometrical, astronomical and meteorological parameters (the independent variables). The independent variables used for this purpose were selected based on their ease of measurability outside the meteorological station and without expensive equipment. The number of independent variables is arbitrarily chosen and directly affects the accuracy of predictions.

Linear regression relations using one, two, three, four, five, six, and seven independent variables were developed to predict the global solar radiation intensity on horizontal surfaces. An advanced computer program based on least square analysis was used to obtain the regression coefficients. The relations having the highest correlation coefficients were selected. The study shows even when only one independent variable (declination angle) is used, the one variable regression relation predicts the global solar radiation with an accuracy that is satisfactory in most engineering applications.

The diversity of regression relations introduced in this paper gives the engineer such a broad freedom of choice, that knowing only an astronomical parameter of the site makes him capable of estimating the global solar radiation intensity within acceptable margins. The predicted values of global solar radiation intensity by this approach can be used for the design and performance estimation in solar applications. The statistical model developed in this research was validated when compared with the measured data in Yazd airport. The measured data used to analyze the model equations were collected in a 13‐year period. No investigation of this type exists having such degree of accuracy in geographical, geometrical, astronomical and meteorological parameters in Iran.

The purpose of this paper is to apply the numerical methods to study the heap leaching process in a bed of porous and spherical ore particles. This study is performed in two stages: first, modeling the leaching process of a soluble mineral from a spherical and porous ore particle to obtain the distribution of mineral concentrations, leaching solvent concentration and dissolved mineral in the particles (the particle model), and second, modeling the heap leaching of the mineral from a porous bed consisting of spherical and porous ore particles to obtain the distribution of mineral concentrations, leaching solvent concentration and dissolved mineral in the bed (the bed model).

The governing equations are derived for the particle model, and then converted into non‐dimensional form using reference quantities. The non‐dimensional equations are discretised on a uniform spherical grid fitted to the particle using finite difference method. The resulting algebraic equations are solved using Tri‐Diagonal Matrix Algorithm, and the governing equations are derived for the bed model, and then converted into non‐dimensional form using reference quantities. The non‐dimensional equations are discretised explicitly on a one‐dimensional and uniform grid fitted to the bed. The unknown quantities are evaluated using the corresponding values at the previous time interval.

The results obtained from numerical modeling show that, when the particle has a low diffusion resistance or a high chemical resistance, the reaction takes place slowly and homogeneously throughout the ore particle. On the other hand, when the bed has a low convection resistance, the reaction takes place homogeneously throughout the bed. As the convection resistance increases, the non‐homogeneous (local) behavior predominates. It is also noticed that, when the chemical reaction resistance is high, the reaction takes place homogeneously throughout the bed.

The dynamic diffusion and movement of solution in the ore particles and ore bed are not modeled and volumetric ratio of solution in the particles and the bed and also vertical velocity of solution in the bed are assumed to be fixed constants.

This study shows that the reaction takes place homogeneously throughout the bed when the convection resistance is low, the diffusion resistance is high, the concentration resistance is low, and the chemical reaction resistance is high.

Homogeneous reaction conditions being suitable for heap leaching operations are identified. Thus, it is recommended to approach the above conditions when preparing ore heaps and designing the relevant operation.

The current world of knowledge has a demand for intellectual capital to position or prosper any business. Organizations are constantly looking for developing a pool of talent to gain a competitive advantage. The purpose of this study is to find out the contribution of knowledge sharing that enhances the performance of the employees. This study also exhibits a model for measuring the performance of the employee.

This study is based on the primary and secondary sources of data. This paper has collected 354 samples from the different information technology (IT) firms located in India. The data were analyzed through statistical package for the social sciences-23 and analysis of moment structures. Path analysis has been conducted to examine the independent and mediating effects on the dependent factor.

This study confirms the conceptual model with the data. The key contributors are organizational intelligence (OI), organizational learning and knowledge sharing and organizational culture. The performance of the employee is primarily based on organizational learning. OI, knowledge sharing and organizational culture are the major factors that create an environment for organizational learning.

The findings suggest that organizational learning stimulates the effect of knowledge management practices on employee performance. Apart from this OI affirms the learning culture for IT firms.

Drawing from the different theories, this is the first study where the role of OI, organizational culture and knowledge sharing simultaneously aligned and shows the effect on employee performance with the mediation role of organizational learning.

This paper develops an empirical means of tracking involvement in a relational double‐bind in hostage negotiations as a means of monitoring the extent to which the hostage takers developed more cooperative or competitive relational parameters with police negotiators. Verbal immediacy was used to track the hostage takers double bind problems across nine different hostage negotiations. The results indicated that the purpose for taking hostages greatly influenced the kinds of paradoxes displayed by the hostage takers. Mentally ill hostage takers became cooperative early in the negotiation, but then turned more competitive as the negotiation unfolded. Hostage takers caught in the act of committing a crime became competitive early and then became more cooperative as time elapsed The hostage takers involved in domestic violence remained competitive throughout the interaction.

The purpose of the paper is to study natural convection within porous square and triangular geometries (design 1: regular isosceles triangle, design 2: inverted isosceles triangle) subjected to discrete heating with various locations of double heaters along the vertical (square) or inclined (triangular) arms.

Galerkin finite element method is used to solve the governing equations for a wide range of modified Darcy number, Da_m = 10⁻⁵–10⁻² with various fluid saturated porous media, Pr_m = 0.015 and 7.2 at a modified Rayleigh number, Ra_m = 10⁶ involving the strategic placement of double heaters along the vertical or inclined arms (types 1-3). Adaptive mesh refinement is implemented based on the lengths of discrete heaters. Finite element based heat flow visualization via heatlines has been adopted to study heat distribution at various portions.

The strategic positioning of the double heaters (types 1-3) and the convective heatline vortices depict significant overall temperature elevation at both Da_m = 10⁻⁴ and 10⁻² compared to type 0 (single heater at each vertical or inclined arm). Types 2 and 3 are found to promote higher temperature uniformity and greater overall temperature elevation at Da_m = 10⁻². Overall, the triangular design 2 geometry is also found to be optimal in achieving greater temperature elevation for the porous media saturated with various fluids (Pr_m).

Multiple heaters (at each side [left or right] wall) result in enhanced temperature elevation compared to the single heater (at each side [left or right] wall). The results of the current work may be useful for the material processing, thermal storage and solar heating applications.

The heatline approach is used to visualize the heat flow involving double heaters along the side (left or right) arms (square and triangular geometries) during natural convection involving porous media. The heatlines depict the trajectories of heat flow that are essential for thermal management involving larger thermal elevation. The mixing cup or bulk average temperature values are obtained for all types of heating (types 0-3) involving all geometries, and overall temperature elevation is examined based on higher mixing cup temperature values.

The internet creates ample opportunities to start a mobile social commerce business. The literature confirms the issue of customer trust for social commerce businesses is a challenge that must be addressed. Hence, this study aims to examine the antecedents of trust in mobile social commerce by applying linear and non-linear relationships based on partial least squares structural equation modeling and artificial neural network model.

This study applied a non-linear artificial neural network approach to provide a further understanding of the determinants of trust in mobile social commerce based on a non-linear and non-compensatory model. Besides, a questionnaire was distributed to 340 social commerce customers in Malaysia.

The conceptual framework for investigating trust in mobile social commerce has various advantages and contributions to predicting consumer behavior. The results of the study showed there is a positive and significant relationship between social support, presence and unified theory of acceptance and use of technology2 (UTAUT2). In addition, UTAUT2 has fully mediated the relationship between social support, presence and trust in social commerce. Finally, the results concluded the relationship between UTAUT2 and trust in social commerce would be stronger when the diffusion of innovation and innovation resistance is high and low, respectively.

The current study provides a novel perspective on how customers can trust social m-commerce to provide real solutions to managers of encouraging e-marketing among consumers.

This paper shows how businesses can develop trust in social m-commerce in Malaysian markets. The findings of this study probably could be extended to other businesses in Asia or other countries. Because trust in social e-commerce has a dynamic role in consumer behavior and intention to purchase.

This study provided a new perspective on mobile social commerce and paid more attention to an investigation of such emerging commerce. The originality of this study is embodied by investigating an integrated model that included different theories that presented new directions of trust in mobile social commerce through social and behavioral determinants.

The purpose of this paper is to investigate the effect of exponential viscosity-temperature relation, exponential thermal conductivity-temperature relation and the combined effects of variable viscosity and variable thermal conductivity on steady free convection flow of viscous incompressible fluid in a vertical channel.

The governing equations are solved analytically using regular perturbation method. The analytical solutions are valid for small variations of buoyancy parameter and the solutions are found up to first order for variable viscosity. Since the analytical solutions have a restriction on the values of perturbation parameter and also on the higher order solutions, the authors resort to numerical method which is Runge-Kutta fourth order method.

The skin friction coefficient and the Nusselt number at both the plates are derived, discussed and their numerical values for various values of physical parameters are presented in tables. It is found that an increase in the variable viscosity enhances the flow and heat transfer, whereas an increase in the variable thermal conductivity suppresses the flow and heat transfer for variable viscosity, variable thermal conductivity and their combined effect.

This research is relatively original as, to the best of the authors’ knowledge, not much work is done on the considered problem with variable properties.

Distance learning has proliferated significantly in the last 20 years. This chapter considers some of the issues and implications when teaching and learning moves from an in-person to a distance mode. It begins with a brief history of distance learning, considering both the technologies used and the dominant pedagogical approaches employed. This is followed by a survey of the impact of Michael Moore's theory of transactional distance, which considered the consequences of separating the learner from peers and instructor. Contemporary work on Moore's contribution includes transaction and participation, activity theory, and transactional presence. A second major aspect of distance learning has been the attempt to introduce social presence into learning environments. The history of social presence is explored, as are its levels and consequences for the learner. Contemporary aspects of social presence reviewed include communities of inquiry. While Web 2.0 has spectacularly resulted in connectivity, it remains unclear as to whether this automatically resulted in more strongly connected learners. Connectivist approaches are considered and distinctions made between technological connectivity and pedagogical engagement. It is argued that the full and exciting potential of Web 2.0 in distance learning requires a commitment to the distanced learner, balancing learner autonomy and teacher presence, promoting meaningful social engagement, and meeting the specific needs of the distance learner.