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Cosco N.G.,North Carolina State University | Moore R.C.,North Carolina State University | Islam M.Z.,Dhaka University of Engineering and Technology
Medicine and Science in Sports and Exercise | Year: 2010

The preschool that children attend has been shown to be a significant but variable predictor of physical activity of 3-to 5-yr-olds, whereas the time outdoors has been found to be a strong correlate of physical activity. Researchers speculate that variations in preschool physical activity may be attributed to variations in preschool policies and practices, including the form and content of outdoor physical environments. However, assessment methods linking them to physical activity are limited. Improved understanding of links between environment and activity could be used to influence childcare policy, which is highly regulated, usually at state level, to create outdoor environments more conducive to children's informal play and physical activity. The purpose of this article was to introduce behavior mapping as a direct observation method on the basis of the theories of behavior setting and affordance and to demonstrate its sensitivity to gathering physical activity and associated environmental data at a sufficiently detailed level to affect built environment design policy. Methods: Behavior mapping data, including outdoor environmental characteristics and children's physical activity levels, were obtained in two preschool centers at the Research Triangle region, NC. Results: Physical activity levels at the two centers varied across different types of behavior settings, including pathways, play structures, and open areas. The same type of setting with different attributes, such as circular versus straight pathways, and open areas with different ground surfaces, such as asphalt, compacted soil, woodchips, and sand, attracted different levels of physical activity. Conclusions: Behavior mapping provides a promising method for objectively measuring relationships between physical behavior settings and directly associated activity levels. Copyright © 2010 by the American College of Sports Medicine.

Faruk Md.S.,Dhaka University of Engineering and Technology | Mori Y.,Nagoya University | Kikuchi K.,University of Tokyo
IEEE Photonics Journal | Year: 2014

We propose a novel method of in-band estimation of optical signal-to-noise ratio (OSNR) using a digital coherent receiver, where OSNR is determined from second- and fourth-order statistical moments of equalized signals in any modulation format. Our proposed method is especially important in recently-developed Nyquist wavelength-division multiplexed (WDM) systems and/or reconfigurable optical-add/drop-multiplexed (ROADM) networks, because in these systems and networks, we cannot apply the conventional OSNR estimation method based on optical-spectrum measurements of the in-band signal and the out-of-band noise. Effectiveness of the proposed method is validated with computer simulations of Nyquist-WDM systems and ROADM networks using 25-Gbaud quadrature phase-shift keying (QPSK) and 16 quadrature-amplitude modulation (16-QAM) formats. © 2009-2012 IEEE.

Rahman A.T.M.M.,Dhaka International University | Alam M.S.,Dhaka University of Engineering and Technology | Chowdhury M.K.,Bangladesh University of Engineering and Technology
International Communications in Heat and Mass Transfer | Year: 2012

In this paper, the effects of thermophoresis particle deposition on an unsteady two dimensional forced convective heat and mass transfer flow past a wedge taking into account the variation of fluid viscosity and fluid Prandtl number with temperature are studied. The local similarity equations are derived and solved numerically using Nachtsheim-Swigert shooting iteration technique along with the sixth order Runge-Kutta integration scheme. Comparisons with previously published work are performed, and the results are found to be in excellent agreement. Results for the non-dimensional velocity, temperature, concentration, Prandtl number and thermophoretic velocity are displayed graphically whereas thermophoretic deposition velocity is shown in the tabulated form for various values of the pertinent parameters. The obtained numerical results show that in modeling the thermal boundary-layer flow with a temperature-dependent viscosity, consideration of the Prandtl number as a constant within the boundary layer produces unrealistic results, and therefore, it must be treated as a variable rather than a constant within the boundary layer. The results also show that the thermophoretic particle deposition velocity decreases as the thermophoretic coefficient increases. © 2012 Elsevier Ltd.

Faruk M.S.,Dhaka University of Engineering and Technology
Optical and Quantum Electronics | Year: 2016

A novel blind equalization and carrier-phase-recovery technique based on modified constant-modulus algorithm is proposed for polarization-division multiplexed quadrature phase-shift keying (PDM-QPSK) systems. The proposed scheme is validated with computer simulations as well as transmission experiments with 40-Gbits/s PDM-QPSK signals. © 2015, Springer Science+Business Media New York.

Mamun A.A.,Jahangirnagar University | Deeba F.,Dhaka University of Engineering and Technology
Plasma Physics Reports | Year: 2015

A theoretical investigation has been made on nonplanar (cylindrical and spherical) dust-ionacoustic (DIA) double layers (DLs) in a multi-ion dusty plasma system containing inertial positive and negative ions and arbitrarily charged stationary dust. The dust particles have been considered as arbitrarily (either positively or negatively) charged in order to observe the effects of the dust polarity on the DIA DLs. The ion species were considered to be at different temperatures to observe the effects of the temperatures on that waves. The modified Gardner equation, which has been derived by employing the reductive perturbation method, has been used to analyze time-dependent nonplanar and planar DIA DLs. It has been found that the time evolution of DIA DLs is significantly modified not only by the nonplanar geometry, but also by the polarity, temperature, and mass ratio of the constituent particles. It has been also found that the amplitude of cylindrical DIA DL structures is larger than that of 1D planar ones, but smaller than that of the spherical ones. © 2015, Pleiades Publishing, Ltd.

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