New approach relevant to total heat transfer coefficient including the effect of radiation and convection at the ceiling in a cooled ceiling room

In this study, radiative and convective heat transfer coefficients at the ceiling are determined for a cooled ceiling room. Firstly, convective heat transfer is simulated numerically neglecting the radiative heat transfer at the surfaces (ε_f = ε_w = ε_c = 0), then, radiative heat transfer is calculated theoretically for different surface emissivities (ε_f = ε_w = ε_c = 0.5, 0.6, 0.7, 0.8 and 0.9) for different room dimensions (3 × 3 × 3, 4 × 3 × 4 and 6 × 3 × 4 m) and thermal conditions (T_f = 25 °C, T_w = 28–36 °C and T_c = 0–25 °C). Numerical data is compared with the results of correlations based on experimental data given in literature. New equations related to convective and total (including the effect of convection and radiation) heat transfer coefficients for ceiling are found in the current study.     

On the Solution of the Black–Scholes Equation Using Feed-Forward Neural Networks

Computational Economics - This paper deals with a comparative numerical analysis of the Black–Scholes equation for the value of a European call option. Artificial neural networks are used for...     

The prediction of convective heat transfer in floor-heating systems by artificial neural networks

In this study the floor Nusselt and Rayleigh numbers for the floor-heating systems are estimated by the artificial neural networks (ANN). Numerical data for the floor Nusselt and Rayleigh numbers are available in the literature. A piece of the numerical values are used for training the ANN. The values estimated by the ANN are compared with the numerical values and the results of an equation given in the literature. It has been seen that the results of the ANN are very close to the numerical data and the results of the equation.     

A study on ideal distance between staggered metal hydride tanks in forced convection

There are several critical parameters in specifying the satisfactory hydrogen flow in metal hydride tanks such dynamic factors in addition to the quantity contained in the tanks. Dynamic factors could be emphasized as ambient conditions and metal hydride properties. This work aims at investigating the effects of equilibrium pressure, ambient air temperature and velocity on ideal distance among metal hydride (MH) tanks used with the purpose of storing hydrogen in fuel cell applications as theoretically and numerically by using Autodesk CFD Simulation software. The metal hydride chosen for the present study is titled as LaNi5 in the literature. A new approach was utilized in the present study to describe the ideal distance among MH tanks using a novel approach in operating different conditions. Analyses implemented in this study are based on various ambient temperatures (i.e. 290K, 300K & 310K), Reynolds Numbers (i.e. 6000, 12,000 & 30,000) and equilibrium pressures (i.e. 60 kPa, 100 kPa & 120 kPa). As emphasized here, the ideal distance among MH tanks will be rather shortened while the Reynolds numbers increase during the operation. Moreover, it is noted here that the ideal distance will not be changed while the equilibrium pressure is in decrease and the ambient temperature is on the increase. Our findings indicate that distance among the MH tanks exists for maximum heat transfer. This finding could be utilized to maximize efficiency of the integrated metal-hydride-Fuel cell system without increasing additional costs.     

Ultra-low-power biopotential interfaces and their applications in wearable and implantable systems

Traditionally the monitoring of the biopotential signals are only limited to clinical applications. On the other hand, there is a growing demand for these biopotential signals to be used in non-clinical applications in order to improve the quality of life and enable the interaction between humans and machines. However, such non-clinical applications of biopotential signal monitoring requires various improvements not only in terms of size and comfort of the biopotential acquisition systems, but also in terms of their power dissipation. An important building block of the biopotential acquisition systems is the front-end circuitry that defines the quality of the extracted signals and unfortunately consumes unacceptable power, when the currently available circuitry is considered. Therefore, this paper focuses on the advances in low-power and high-performance readout circuit design for the acquisition of biopotential signals. In addition, several application examples will be demonstrated, which proves that the realization of high-performance and low-power readout circuits can actually enable the implementation of miniaturized and comfortable biopotential acquisition systems extending the usage of such systems towards non-clinical applications.     

An empirical study on evolutionary feature selection in intelligent tutors for learning concept detection

Concept map mining (CMM) has emerged as a new research area with recent developments in computational intelligence in educational technology. CMM includes the following steps: extracting the learning concepts from educational content, specifying relations among them, and generating a concept map as a result. The purpose of this study was to develop a mechanism using data mining technique to determine the features that characterize a learning concept extracted automatically from a single educational text. The 3 major features that distinguish the real learning concepts from other sequences of strings are detected by using a hybrid system of a feed‐forward neural network and some evolutionary algorithms. Ant colony optimization and genetic algorithm and particle swarm optimization are used as a binary feature selection method. In addition, the aforementioned methods are hybridized to get better accuracy and precision. The performance comparisons with two different state‐of‐the‐art algorithms have been made from the viewpoint of a typical classification problem.     

A numerical investigation on effects of ceiling and floor surface temperatures and room dimensions on the Nusselt number for a floor heating system

In this study, the effect of ceiling and floor surface temperatures and room dimensions on the Nusselt number over the floor of a floor heating system has been investigated numerically. The variation of the Nusselt number with Rayleigh number has been analyzed under constant wall temperature condition for different ceiling temperatures (10–25 °C) and room dimensions. It has been seen that when the room dimensions and temperature difference between the ceiling and interior air are increased, the Nusselt number over the floor increases as well. The numerical results have been compared with the correlations given in the literature. It has been seen that the correlations available in the literature are valid only for given thermal conditions and room dimensions. The results calculated from the correlations which do not consider the effects of ceiling and floor surface temperatures deviate up to 35% than the results of this numerical study carried out for different ceiling and floor surface temperatures and room dimensions. Therefore, a new correlation for Nusselt number over the floor, which contain the influence of thermal conditions and all of room dimensions must be discovered.