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Open access

M. Ferdows, Md. Shakhaoath Khan, Md. Mahmud Alam and A. A. Afify

Abstract

The study of radiative heat transfer in a nanofluid with the influence of magnetic field over a stretching surface is investigated numerically. Physical mechanisms responsible for magnetic parameter, radiation parameter between the nanoparticles and the base fluid, such as Brownian motion and thermophoresis, are accounted for in the model. The parameters for Prandtl number Pr, Eckert number Ec, Lewis number Le, stretching parameter b/a and constant parameter m are examined. The governing partial differential equations were converted into nonlinear ordinary differential equations by using a suitable similarity transformation, which are solved numerically using the Nactsheim-Swigert shooting technique together with Runge-Kutta six order iteration scheme. The accuracy of the numerical method is tested by performing various comparisons with previously published work and the results are found to be in excellent agreement. Numerical results for velocity, temperature and concentration distributions as well as skin-friction coefficient, Nusselt number and Sherwood number are discussed at the sheet for various values of physical parameters.

Open access

Damian Borys, Katarzyna Szczucka-Borys and Kamil Gorczewski

System matrix computation for iterative reconstruction algorithms in SPECT based on direct measurements

A method for system matrix calculation in the case of iterative reconstruction algorithms in SPECT was implemented and tested. Due to a complex mathematical description of the geometry of the detector set-up, we developed a method for system matrix computation that is based on direct measurements of the detector response. In this approach, the influence of the acquisition equipment on the image formation is measured directly. The objective was to obtain the best quality of reconstructed images with respect to specified measures. This is indispensable in order to be able to perform reliable quantitative analysis of SPECT images. It is also especially important in non-hybrid gamma cameras, where not all physical processes that disturb image acquisition can be easily corrected. Two experiments with an 131 I point source placed at different distances from the detector plane were performed allowing the detector response to be acquired as a function of the point source distance. An analytical Gaussian function was fitted to the acquired data in both the one- and the two-dimensional case. A cylindrical phantom filled with a water solution of 131 I containing a region of "cold" spheres as well as a uniform solution (without any spheres) was used to perform algorithm evaluation. The reconstructed images obtained by using four different of methods system matrix computation were compared with those achieved using reconstruction software implemented in the gamma camera. The contrast of the spheres and uniformity were compared for each reconstruction result and also with the ranges of those values formulated by the AAPM (American Association of Physicists in Medicine). The results show that the implementation of the OSEM (Ordered Subsets Expectation Maximization) algorithm with a one-dimensional fit to the Gaussian CDR (Collimator-Detector Response) function provides the best results in terms of adopted measures. However, the fit of the two-dimensional function also gives satisfactory results. Furthermore, the CDR function has the potential to be applied to a fully 3D OSEM implementation. The lack of the CDR in system matrix calculation results in a very noisy image that cannot be used for diagnostic purposes.

Open access

Florent Bernard, Viktor Fischer and Boyan Valtchanov

References [1] BUCCI, M.-LUZZI, R.: Design of testable random bit generators , in: Cryptographic Hardware and Embedded Systems-CHES ’05, 7th International Workshop (J. Rao, B. Sunar, eds.), Lecture Notes in Comput. Sci., Vol. 3659, Springer-Verlag, Berlin, 2005, pp. 147-156. [2] KOHLBRENNER, P.-GAJ, K.: An embedded true random number generator forFPGAs , in: Proc. of the 2004 ACM/SIGDA 12th Internat. Symposium on Field Programmable Gate Arrays-FPGA 04, ACM New York, NY, 2004, pp. 71-78. [3] SUNAR, B

Open access

Tadeusz Kaczorek

References Bistritz, Y. (2003). A stability test for continuous-discrete bivariate polynomials, Proceedings of the International Symposium on Circuits and Systems , Vol. 3, pp. 682-685. Busłowicz, M. (2010a). Stability and robust stability conditions for a general model of scalar continuous-discrete linear systems, Pomiary, Automatyka, Kontrola 56(2): 133-135. Busłowicz, M. (2010b). Robust stability of the new general 2D model of a class of continuous-discrete linear systems

Open access

Marilena Crupi and Giancarlo Rinaldo

, Four strikes against physical mapping of DNA , J. Comput. Biol., 2 (1995), 139–152. [10] M. C. Golumbic, Algorithm Graph Theory and Perfect graphs , Academic Press, New York, N.Y., 1980. [11] M. Habib, R. McConnel, C. Paul, L.Viennot, Lex-BFS and partition refinement, with applications to transitive orientation, interval graph recognition, and consecutive one testing , Theoret. Comput. Sci., 234 (2000), 59–84 [12] G. Hajós, Über eine Art von Graphen , Internat. Math. Nachrichten, 11 (1957) problem 65. [13] P. Heggernes, D. Meister, C

Open access

Mikołaj Busłowicz and Andrzej Ruszewski

, Proceedings of the IFAC Workshop on Time-Delay Systems (TDS 2003), Rocquencourt, France , (CD-ROM). Gałkowski, K., Rogers, E., Paszke, W. and Owens, D. H. (2003). Linear repetitive process control theory applied to a physical example, International Journal of Applied Mathematics and Computer Science   13 (1): 87-99. Guiver, J. P. and Bose, N. K. (1981). On test for zero-sets of multivariate polynomials in noncompact polynomials, Proceedings of the IEEE   69 (4): 467-469. Hespanha, J. (2004

Open access

Fengxiang Zhang, Yanfeng Zhai and Jianwei Liao

). Control robotics: The procedural control of physical processes, IFIP Congress, Stockholm, Sweden , pp. 807–813. Devi, M. (2003). An improved schedulability test for uniprocessor periodic task systems, Proceedings of the 15th Euromicro Conference on Real-Time Systems, Porto, Portugal , pp. 23–30. Ghazalie, T.M. and Baker, T.P. (1995). Aperiodic servers in a deadline scheduling environment, Real-Time Systems 9 (1): 31–67. Harbour, M.G. and Palencia, J.C. (2003). Response time analysis for tasks scheduled under EDF within fixed priorities, 24th IEEE

Open access

Aleksander Weron

References [1] Barkai E., Metzler R., Klafter J., From continuous time random walks to the fractional Fokker-Planck equation, Phys. Rev. E 61 (2000), 132-138. [2] Barndorff-Nielsen O.E., Normal//inverse Gaussian Processes and the Modelling of Stock Returns, Research Report 300, Department of Theoretical Statistics, University of Aarhus, 1995. [3] Beran J., Statistics for Long-Memory Processes, Chapman and Hall, New York, 1994. [4] Brcich R.F., Iskander D.R., Zoubir A.M., The stability test for

Open access

Hyunjoo Park and M. Mandy Sha

Retention of Older Ethnic Minority Adults into Clinical Research. Journal of Consulting and Clinical Psychology, 64, 875-880. Berrigan, D., Forsyth, B.H., Helba, C., Levin, K., Norberg, A., and Willis, G. (2010). Cognitive Testing of Physical Activity and Acculturation Questions in Recent and Long-Term Latino Immigrants. BioMed Central Public Health, 10(481). Available at: http://www.biomedcentral.com/content/pdf/1471-2458-10-481.pdf (accessed March 2012). Bistricky, S.L., Mackin, R.S., Chu, J.P., and Arean, P.A. (2010

Open access

Cili Zuo, Lianghong Wu, Zhao-Fu Zeng and Hua-Liang Wei

, K., Thiele, L., Laumanns, M. and Zitzler, E. (2005). Scalable Test Problems for Evolutionary Multiobjective Optimization, Springer, London. Denysiuk, R., Costa, L., Santo, I.E. and Matos, J.C. (2015). MOEA/PC: Multiobjective evolutionary algorithm based on polar coordinates, International Conference on Evolutionary Multi-Criterion Optimization, Guimar˜aes, Portugal, pp. 141-155. Derrac, J., García, S., Molina, D. and Herrera, F. (2011). A practical tutorial on the use of nonparametric statistical tests as a methodology for comparing