2011
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Numerical Simulation of Random Irregular Waves for Wave Generation in Laboratory Flumes
Numerical Simulation of Random Irregular Waves for Wave Generation in Laboratory Flumes
2
2
Understanding of wave hydrodynamics and its effects are important for engineers and scientists. Important insights may be gained from laboratory studies. Often the waves are simulated in laboratory flumes do not have the full characteristics of real sea waves. It is then necessary to present reliable methods of wave generation in wave flumes. In this paper, the results of numerically simulated water waves using different methods are presented. A model was developed to simulate water wave profile using DSA, NAS and WNDF methods. The results showed that although DSA method provides better agreement between output and target spectra, it is associated with non realistic simulation of sea waves. In the other hand WNDF method involves better stochastic wave characteristics if a qualitative white noise is used. It is also possible to put some controls on wave characteristics as input to WNDF model.
1
Understanding of wave hydrodynamics and its effects are important for engineers and scientists. Important insights may be gained from laboratory studies. Often the waves are simulated in laboratory flumes do not have the full characteristics of real sea waves. It is then necessary to present reliable methods of wave generation in wave flumes. In this paper, the results of numerically simulated water waves using different methods are presented. A model was developed to simulate water wave profile using DSA, NAS and WNDF methods. The results showed that although DSA method provides better agreement between output and target spectra, it is associated with non realistic simulation of sea waves. In the other hand WNDF method involves better stochastic wave characteristics if a qualitative white noise is used. It is also possible to put some controls on wave characteristics as input to WNDF model.
1
6


Mohammad Janvad
Ketabdari
Iran


Ali
Ranginkaman
Iran
Random Irregular Waves
DSA Method
NSA Method
WNDF Method
White Noise
[[1] R. Firoozkoohi, M. J. Ketabdari, (2008): "Design of irregular wave maker for marine laboratory", First Conference of Advances in Marine Industry, Amirkabir University of Technology, Tehran, Iran, 2007. ##[2] S. O. Rice, (1944): “Mathematical analysis of random noise”, Bell System Tech. J., Vol. 23, 1944 and Vol. 24, 1945. (Reprinted in selected papers on noise and stochastic processes, N. Wax (Ed.), Dover Pub. Inc., New York, N. Y., 1954, pp. 123144). ##[3] E. R. Funke, and Mansard, and E. P. D. Dai, G., (1988): “Realisable wave parameters in a laboratory flume”, Proc. 21st Int. Conf. Coastal Eng., ASCE, Vol. 1, pp. 835848. ##[4] S. A. Hughes, (1993): Physical models and laboratory techniques in coastal engineering, JBW printers & binders Pte. Ltd., London. ##[5] H. Gravesen, and T., Sorensen, (1977): “Stability of rubble mound breakwaters”, Proc. 23rd PIANC Conf., Leningrad. ##[6] D. Brook, and R. J. Wynne, (1988): Signal Processing Principles and Applications", Edward Arnold. ##[7] J. S. Bendat, and A. G. Piersol, (1986): Random data analysis and measurement, John Wiley and Sons Inc., New York. ##[8] M. Kendall, and K. Ord, (1986): Time Series, Mc Graw_Hill .Inc. ##[9] S. Haykin, (1993): Communication Systems, John Wiley & sons Inc ##[10] K. S. Shanmugan, and A. M. Breipohl, (1998): Random signals – Detection, Estimation, and Analysis John Wiley and Sons, inc. ##[11] E.R. Funke, and E.P.D., Mansard, (1987):“A rationale for the use of the deterministic approach to laboratory wave generation”, Proc. 22nd Cong. Int. Associated for Hydraulic Res., pp. 153195.##]
A multi Agent System Based on Modified Shifting Bottleneck and Search Techniques for Job Shop Scheduling Problems
A multi Agent System Based on Modified Shifting Bottleneck and Search Techniques for Job Shop Scheduling Problems
2
2
This paper presents a multi agent system for the job shop scheduling problems. The proposed system consists of initial scheduling agent, search agents, and schedule management agent. In initial scheduling agent, a modified Shifting Bottleneck is proposed. That is, an effective heuristic approach and can generate a good solution in a low computational effort. In search agents, a hybrid search approach is presented. The schedule management agent can manage the system. Finally, the proposed agent based system is tested and validated by some benchmark problems. The results show the superiority of the proposed system in terms of makespan minimization and CPU times.
1
This paper presents a multi agent system for the job shop scheduling problems. The proposed system consists of initial scheduling agent, search agents, and schedule management agent. In initial scheduling agent, a modified Shifting Bottleneck is proposed. That is, an effective heuristic approach and can generate a good solution in a low computational effort. In search agents, a hybrid search approach is presented. The schedule management agent can manage the system. Finally, the proposed agent based system is tested and validated by some benchmark problems. The results show the superiority of the proposed system in terms of makespan minimization and CPU times.
7
15


M.H
Karimi Gavareshki
Iran


M.H
Fazel Zarandi
Iran
Job shop scheduling
multi agent system
shifting Bottleneck
search technique
[[1] J. Adams, E. Balas, D. Zawack, "The shifting bottleneck procedure for job shop scheduling," Management Science, 34, 391–401, 1988. ##[2] K. Anke, R Staudte and W. Dilger, Producing and improving timetables by means of constraints and agents, Technical Report WS9705, AAAI Press, Menlo Park, CA,pp. 142147, 1997. ##[3] D. Applegate, W. Cook, "A computational study of job shop scheduling problem," ORSA Journal of Computing, 3149–156, 1991. ##[4] M. E. Aydin, T.C. Fogarty, Teams of autonomous agents for jobshop scheduling problems: An Experimental Study, Journal of Intelligent Manufacturing, 15(4), (2004) 455–462. ##[5] E. Balas, J.K. Lenstra, Vazacopoulos, "The One machine Problem with Delayed Precedence Constraints and its use in Job Shop Scheduling," Management Science, 41, 1, 94109, 1995. ##[6] E. Balas, A.Vazacopoulos, Guided local search with shifting bottleneck for job shop scheduling. Management Science, 44(2):262–75, 1998. ##[7] J Blazewicz, W Domschke, E. Pesch, The job shop scheduling problem: conventional and new solution techniques. European Journal of Operational Research, 93, 1–33, 1996. ##[8] P. Burke and P. Prosser, The Distributed Asynchronous Scheduler, in: Intelligent Scheduling, M.B. Morgan, ed., Morgan Kaufman Publishers, Inc., San Francisco, pp. 309–339, 1994. ##[9] J. Carlier, "The onemachine sequencing problem," European Journal of Operational Research, 11, 4247, 1982. ##[10] S. DauzerePeres, J.B. Lasserre," A modified shifting bottleneck procedure for jobshop scheduling," International Journal of Production Research, 31, 923932, 1993. ##[11] M. Dell’Amico, Trubian M. Applying tabusearch to jobshop scheduling problem.Annals of Operations Research, 41,231–52, 1993. ##[12] E. Demirkol, S.V. Mehta, R. Uzsoy," A computational study of shifting bottleneck procedures for shop scheduling, " J. Heuristics, 3, 111–137, 1997. ##[13] U. Dorndorf, E. Pesch, Evolution based learning in a job shop scheduling environment. Comput. Oper. Res., 22, 25–44, 1995. ##[14] J. Ferber, (1999) Multiagent systems: An introduction to Distributed Artificial Intelligence. Addison Wesley, London. ##[15] H. Fisher and D.L. Thompson, "Probabilistic learning combinations of local job shop scheduling rules," In J. F. Muth, G. L. Thompson (eds.), Industrial Scheduling, PrenticeHall, Englewood Cliffs, 1963. ##[16] M.R. Garey, D.S. Johnson, "Computers and Intractability: A Guide to the Theory of NP Completeness," San Francisco Freeman, 1979. ##[17] F. Glover, M. Laguna, Tabu search. Dordrecht: Kluwer Academic Publishers; 1997. ##[18] AS. Jain, S. Meeran, Deterministic job shop scheduling: past, present and future. European Journal of Operational Research, 113, 390–434, 1999. ##[19] E.L. Lawler, J.K. Lenstra, A.H.G. Rinnooy Kan, "Recent developments in deterministic sequencing and scheduling: a survey" in M. A. H. Dempster, J.K. Lenstra and A.H.G. Rinnooy Kan , Deterministic and Stochastic Scheduling, Reidel, Dordrecht, 1982. ##[20] HD Matsuo, CJ Suh, RS Sullivan, A controlled search simulated annealing method for general job shop scheduling problem. Working Paper, 030488, Department of Management, The University of Texas at Austin, Austin, TX, 1988. ##[21] G.B. McMahon and M. Florian, "On scheduling with ready times and due dates to minimize maximum lateness,” Operations Research, 23, 415482, 1975. ##[22] S. Mukherjee and A.K. Chatterjee, "On the representation of the one machine sequencing problem, " Eur. J. Oper. Res, doi:10.1016/j.ejor.2006.07.024. ##[23] S. Murthy, “Synergy in Cooperating Agents: Designing Manipulators from Task Specifications,” Ph.D. dissertation, Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, 1992. ##[24] E. Nowicki, C. Smutnicki, A fast taboo search algorithm for the job shop scheduling problem.Management Science, 42, 6, 797–813, 1996. ##[25] L. Schrage, "Obtaining optimal solutions to resource constrained network scheduling problem," Unpublished manuscript 1971. ##[26] M Sevkli, M. E. Aydin, Variable Neighbourhood Search for Job Shop Scheduling Problems, Journal of software, V.1, N. 2, August 2006. ##[27] W. Shen, Q. Hao, H. J. Yoon, D.H. Norrie, Applications of agentbased systems in intelligent manufacturing:An updated review, Advanced Engineering Informatics 20 (2006) 415–431. ##[28] S.Talukdar, Asynchronous teams. Proceedings of the 4th international symposium on expert systems applications to power systems, LaTrobe university,Melbourne, Australia. ##[29] A. Tharumarajah and R. Bemelman, Approaches and issues in scheduling a distributed shop floor environment, Computers in industry, 34, 95109, 1997. ##[30] R. Uzsoy and C.S. Wang, "Performance of decomposition procedures for job shop scheduling problems with bottleneck machines," Int. J. Prod. Res., 38, 1271–1286, 2000. ##[31] PJM. Van Laarhoven, EHL Aarts, JK. Lenstra, Job shop scheduling by simulated annealing. Operations Research , 40, 1, 113–125, 1992. ##[32] H. Wenqi and Y. Aihua, "An improved shifting bottleneck procedure for the job shop scheduling problem," Computer & Operations Research, 31, pp. 20932110, 2004. ##[33] M. Wooldridge, An introduction to multiagent systems. John Wiley & Sons, Ltd., Chichester, England. , 2002. ##[34] C.S. Wu, D.C. Li, T.I. Tsai, "Applying the fuzzy ranking method to the shifting bottleneck procedure to solve scheduling problems of uncertainty," Int. J. Adv. Manuf. Technol., 31, 98–106, 2006. ##[35] C.Y. Zhang, P. Li, Z. Guan, Y. Rao, A tabu search algorithm with a new neighborhood structure for the job shop scheduling problem Computers & Operations Research doi:10.1016/j.cor.2005.12.002. ##[36] Z. D. Zhou, H. H. Wang, Y. P. Chen, W. Ai, S. K. Ong, J. Y. H. Fuh and A. Y. C. Nee, A MultiAgentBased Agile Scheduling Model for a Virtual Manufacturing Environment, Int. J Adv Manuf. Technol., 21, 980–984, 2003.##]
Fuzzy Model of Human’s Performance for Guarding a Territory in an Air Combat
Fuzzy Model of Human’s Performance for Guarding a Territory in an Air Combat
2
2
This paper proposes a new method for a three dimensional fuzzy model of pilot's performance for guarding a territory with a shortdistance between two aircraft in an air combat task with a gun. A thirdorder nonlinear point mass vehicle model is considered for an aircraft's flight dynamics. The desired value of the velocity, the flight path and the heading angles are obtained from some derived equations and rule bases developed in this paper. The physical control parameters are computed through a mean square error scheme. To model pilot's performance and generate a complicated offensive maneuver in an air combat, we need to imitate pilot's decisions making performance. The proposed model shows promising performance in all scenarios in which two aircraft can hold in an air combat. This model employs a time optimal combination of classic pursuits when needed. This makes our model very powerful. We consider two cases for modeling, the first one is the model of the pilots with constant specific energy and the other is with time varying specific energy. Finally, this paper proposes a new 3Dimentional flight simulator.
1
This paper proposes a new method for a three dimensional fuzzy model of pilot's performance for guarding a territory with a shortdistance between two aircraft in an air combat task with a gun. A thirdorder nonlinear point mass vehicle model is considered for an aircraft's flight dynamics. The desired value of the velocity, the flight path and the heading angles are obtained from some derived equations and rule bases developed in this paper. The physical control parameters are computed through a mean square error scheme. To model pilot's performance and generate a complicated offensive maneuver in an air combat, we need to imitate pilot's decisions making performance. The proposed model shows promising performance in all scenarios in which two aircraft can hold in an air combat. This model employs a time optimal combination of classic pursuits when needed. This makes our model very powerful. We consider two cases for modeling, the first one is the model of the pilots with constant specific energy and the other is with time varying specific energy. Finally, this paper proposes a new 3Dimentional flight simulator.
17
24


R.
Ghasemi
Iran


S.K.Y.
Nikraveshii
Iran


M.B.
Menhajiii
Iran


S.
Akbariiv
Iran
Fuzzy modeling
Guarding a territory
Pilot's performance
Maneuvering Offender
Pursuit Evasion Game
flight simulator
[[1] Hammer J.M., Small R.L., An intelligent interface in an associate system, In Rouse W B (ed. ) Human / technology interactions in complex systems, vol.7, pp. 871882, 1996. ##[2] Rodin E.Y., Geist D., Lirov Y., Flight and fire control knowledge representation, proceeding 28th IEEE CDC, 1989, pp.779780. ##[3] Lin C.L. and Chen Y.Y., Design of fuzzy logic guidance law against high speed target, Journal of guidance, control and dynamics, No.1, Vol.23, pp.1725, 2000. ##[4] Akbari S., Menhaj M.B., A fuzzy guidance law for modeling offensive airtoair combat maneuvers, IEEE conf, IFSA World congress and 20th NAFIPS international conference, pp.30273031, 2001. ##[5] Akbari S., Qualitative model of pilot performance in air to air combat task: fuzzy set theory approach., Phd dissertation, Electrical Department, AUT, Iran, 2002. ##[6] Virtanen K., Raivio T., Hamalainen R.P., Modeling pilot's sequential maneuvering decisions by multistage influence diagram, Proceeding of AIAA guidance, control and dynamics conference, pp. 175181, 2001. ##[7] Menon P.K. and Duck E.L., Time optimal pursuit evasion with weapon envelope constraint, journal of guidance, control and dynamics, vol. 15, No.2, 1992, pp.448456. ##[8] Jamark B., A missile duels between two aircraft, journal of guidance, control and dynamics, vol.8, No.4, 1985, pp.508513. ##[9] Guelman M. and Shinar J., Optimal guidance law in the plane, Journal of Guidance, Control and Dynamics, vol.8, No.4, 1985, pp.471476. ##[10] K. H. Hisa and J. G. Hsieh, “A first approach to fuzzy differential game problem: guarding a territory,” fuzzy sets and system, vol. 55, 1993, pp. 157167. ##[11] H. J. Chu, J. G. Hsieh, K. H. and L. W. Chen, “Fuzzy differential game of guarding a movable territory,” Information Sciences, vol. 91, pp. 113131, 1996. ##[12] Ghasemi R, Nikravesh SKY, Menhaj MB, Akbari S, “A near optimal fuzzy model of pursuitevasion in an air combat”, WSEAS TRANSACTIONS ON MATHEMATICS, Issue 3, Volume 3, 2004, pp 514521. ##[13] Ghasemi R, Nikravesh SKY, Menhaj MB, Akbari S,” A 3D fuzzy model of pilot’s performance in the dogfight”, WSEAS TRANSACTIONS ON MATHEMATICS, Issue 3, Volume 3, 2004, pp 625631. ##[14] Anderson J.D., Introduction to flight, McGrow Hill, 3rd edition, 1989. ##[15] Shaw R.L., Fighter combat: Tactics and Maneuvering, 1st edition, United States Naval Inst., 1988. ##[16] Rappier, ACM, training: Angle Tactics, http://www.musketeers.org. ##[17] Crenshaw D., How to live and die in the virtual sky, http://www.sci.fi/~fta/acmintro.htm. ##[18] Tran C., Abraham A. and Jain L.,” A Concurrent FuzzyNeural Network Approach for Decision Support Systems”, IEEE International Conference on Fuzzy Systems, pp. 10921097, 2003 ##[19] Wang T.C., Chang T.H., “Application of TOPSIS In Evaluating Initial Training Aircraft Under A Fuzzy Environment”, Expert Systems with Applications 33, pp. 870–880, 2007 ##[20] Wang J., Fan K., Su Y., Liang S., and Wang W., “Air Combat Effectiveness Assessment of Military Aircraft Using a Fuzzy AHP and TOPSIS Methodology”, IEEE 7th intl. conf. on system simulation and scientific computing, pp. 655662, 2008. ## Zhang K., Zhou D., “Application of Improved FCM on Classification of MultiTarget Guided by AWACS”, IEEE computer Society, Fifth International Conference on Fuzzy ##]
Numerical Simulation and Parametric Study of Forced Convective Condensation in Vertical Channel
Numerical Simulation and Parametric Study of Forced Convective Condensation in Vertical Channel
2
2
Forced convective condensation in vertical channel is investigated numerically. The condensation boundary layers that occur due to temperature difference between the walls and saturation temperature of steam is simulated by the volume of fluid (VOF) method. The effect of variations in the hydraulic diameter, steam velocity, Re number and temperature difference between the wall and saturation temperature of inlet steam on heat transfer coefficients are investigated. Simulation results showed that the condensation length and heat transfer coefficient increase by the increase in the amount of inlet velocity and Reynolds number of inlet steam. Also, it was seen a reduction in temperature difference between the wall and saturated steam.
1
Forced convective condensation in vertical channel is investigated numerically. The condensation boundary layers that occur due to temperature difference between the walls and saturation temperature of steam is simulated by the volume of fluid (VOF) method. The effect of variations in the hydraulic diameter, steam velocity, Re number and temperature difference between the wall and saturation temperature of inlet steam on heat transfer coefficients are investigated. Simulation results showed that the condensation length and heat transfer coefficient increase by the increase in the amount of inlet velocity and Reynolds number of inlet steam. Also, it was seen a reduction in temperature difference between the wall and saturated steam.
25
34
Condensation
numerical simulation
Vertical channel
heat transfer coefficient
[[1] Kakac, S., A.E. Bergles, F. Mayinger, “Heat Exchanger,ThermalHydraulic Fundamentals and Design”, Hemisphere publication, Mc GrawHill Book Company 198. ##[2] Saunders, E. A.D., “Heat Exchangers”, John Wiley & Sons, Inc, 1988. ##[3] W.X. Jin, S.C. Low, Terence Quek, “Preliminary experimental study of falling film heat transfer on a vertical doubly fluted plate”, Journal of Desalination 152 (2002) 201206. ##[4] C.P. Ribeiro Jr., M.H. Andrade, “A heat transfer model for the steadystate simulation of climbingfallingfilm plate evaporators”, Journal of Food engineering 54 (2002) 309320. ##[5] M. El Haj Assad, Markku J. Lampinen, “Mathematical modeling of falling liquid film evaporation process”, International Journal of Refrigeration 25 (2002) 985991. ##[6] S. Wellsandt, L. Vamling, “Heat transfer and pressure drop in a platetype evaporator”, International Journal of Refrigeration 26 (2003) 180188. ##[7] Lieke Wang, Bengt Sunden, “Optimal design of plate heat exchangers with and without pressure drop specifications”, Applied Thermal Engineering 23 (2003) 295311. ##[8] Jorge A. W. Gut. Jose M. Pinto, “Modeling of plate heat exchangers with generalized configurations”, International Journal Heat and Mass Transfer 46 (2003) 25712585. ##[9] DongHyouck Han, KyuJung Lee, YoonHo Kim, “Experiments on the characteristics of evaporation of R410A in brazed plate heat exchangers with different geometric configurations”, Applied Thermal Engineering 23 (2003) 12091225. ##[10] Yoichi Shiomi, Shigeyasu Nakanishi, Takafumi Uehara, “Characteristics of twophase flow in a channel formed by chevron type plates”, Experimental Thermal and Fluid Science 28 (2004) 231235. ##[11] Jorge A. W. Gut, Jose M. Pinto, “Optimal configuration design for plate heat exchangers”, International Journal Heat and Mass Transfer 47 (2004) 48334848. ##[12] Reinhard Wurfel, Nikolai Ostrowski, “Experimental investigations of heat exchangers of the herringbonetype” ,International Journal of thermal sciences 43 (2004) 5968. ##[13] P. K. Pandy, “Twodimensional turbulent film condensation of vapors flowing inside a vertical tube and between parallel plates: a numerical approach”, Refrigeration J., 26 (2003) 492503. ##[14] G.A. Longo , A. Gasparella, R. Sartori, “Experimental heat transfer coefficients during refrigerant vaporisation and condensation inside herringbonetype plate heat exchangers with enhanced surfaces”, International Journal Heat and Mass Transfer 47 (2004) 41254136. ##[15] Henning Raach, Jovan Mitrovic, “Simulation of heat and mass transfer in a multi effect distillation plant for seawater desalination", Journal of Desalination 183 (2005) 307316 ##[16] R.K.Kamali, A. Abbassi, S.A. Sadough, “A simulation model and parametric study of MEDTVC process”, EDS international conference, EuroMed (2006) 118123. ##[17] KouhiKamali R., Abbassi, A., Sadough, S. A., Saffar Avval, M., “Thermodynamic Design and Parametric study of MEDTVC”, Desalination J., 222(2008) 607615. ##[18] Seban, R. A., and Faghri, A., 1984, “Film Condensation in a Vertical Tube with a Closed Top”, Int. J. Heat Mass Transfer, pp. 944948. ##[19] F. Kafi, V. Renaudin, D. Alonso, J.M. Hornut, “New MED plate desalination process: Thermal performances”, Journal of Desalination 166 (2004) 5362. ##[20] Zhang, Y., Faghri, A., Shafii, M. B., 2001, “Capillary Blocking in Forced Convective condensation in Horizental Miniature Channels”, Journal of Heat Transfer, pp. 501510.##]
Velocity Modeling in a Vertical Transversely Isotropic Medium Using Zelt Method
Velocity Modeling in a Vertical Transversely Isotropic Medium Using Zelt Method
2
2
In the present paper, the Zelt algorithm has been extended for ray tracing through an anisotropic model. In anisotropic media, the direction of the propagated energy generally differs from that of the planewave propagation. This makes velocity values to be varied in different directions. Therefore, velocity modeling in such media is completely different from that in an isotropic media. The velocity model for ray tracing is parameterized in terms of blocky trapezoid cells where the velocity changes inside the cells linearly. Thomsen’s approximations in weakly anisotropic media were used to estimate anisotropic velocity vectors. Rays were traced in direction of group vector in the vertical transversely isotropic (VTI) media, whereas, the anisotropic Snell’s law must be satisfied by the phase angle and phase velocities across the interface. The synthetic examples are given to demonstrate and verify the ray tracing algorithm. Reflected and turning waves were traced through the isotropic and anisotropic velocity models. Lateral and vertical velocity variation caused deviation on trajectory of the traveltime curve. The results show that the difference between isotropic and anisotropic traveltimes increases with offset, especially when the ratio offset/depth exceeds 1.5.
1
In the present paper, the Zelt algorithm has been extended for ray tracing through an anisotropic model. In anisotropic media, the direction of the propagated energy generally differs from that of the planewave propagation. This makes velocity values to be varied in different directions. Therefore, velocity modeling in such media is completely different from that in an isotropic media. The velocity model for ray tracing is parameterized in terms of blocky trapezoid cells where the velocity changes inside the cells linearly. Thomsen’s approximations in weakly anisotropic media were used to estimate anisotropic velocity vectors. Rays were traced in direction of group vector in the vertical transversely isotropic (VTI) media, whereas, the anisotropic Snell’s law must be satisfied by the phase angle and phase velocities across the interface. The synthetic examples are given to demonstrate and verify the ray tracing algorithm. Reflected and turning waves were traced through the isotropic and anisotropic velocity models. Lateral and vertical velocity variation caused deviation on trajectory of the traveltime curve. The results show that the difference between isotropic and anisotropic traveltimes increases with offset, especially when the ratio offset/depth exceeds 1.5.
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40
Ray tracing
Vertical Transversely Isotropy (VTI)
Zelt method
seismic velocity modeling
[[1] J.G. Berryman, “Longwave elastic anisotropy in transversely isotropic media,” Geophysics, vol. 44, pp. 896917, 1979. ##[2] V. Cerveny, I.A. Molotkov, and I. Psencik, Ray method in seismology, Universita Karlova, 1977. ##[3] V. Cerveny, The application of raytracing to the numerical modeling of seismic wavefields in complex structures, Handbook of geophysical exploration, Geophysical Press, London, 1985. ##[4] V. Grechka, I. Tsvankin, “PP+PS=SS,” Geophysics, vol. 67, pp. 19611971, 2002. ##[5] K. Helbig, “Systematic classification of layerinduced transverse isotropy,” Geophy. Prosp., vol. 29, pp. 550577, 1981. ##[6] K. Helbig, Foundations of anisotropy for exploration seismic. Handbook of Geophysical Exploration. Oxford, Pergamon, 1994. ##[7] B.R. Julian, and D. Gubbins, “3D seismic ray tracing,” Geophysics, vol. 43, pp. 95113, 1977. ##[8] Th. Krey, K. Helbig, “A theorem concerning anisotropic stratified media and its significance for reflection seismic,” Geophy. Prosp., vol. 4, pp. 294 302, 1956. ##[9] F.K. Levin, “The reflection, refraction of waves in media with elliptical velocity dependence,” Geophysics, vol. 43, pp. 528 537, 1978. ##[10] A. Lomax, “Wavelengthsmoothing method for approximating broadband wave propagation through complicated velocity structures,” Geophysics. J. Int., vol. 117, pp. 313334, 1994. ##[11] T. J. Moser, “Shortest path calculation of seismic rays,” Geophysics, vol. 59, pp. 5967, 1991. ##[12] P. Podvin, and I. Lecomte, “Finite difference computation of traveltimes in very contrasted velocity models: a massively parallel approach and its associated tools,” Geophys. J. Int., vol. 105, pp. 271284, 1991.##]
Equation Chapter 1 Section 1 Analytical Solutions for Radially Functionally Graded Annular Plates
Equation Chapter 1 Section 1 Analytical Solutions for Radially Functionally Graded Annular Plates
2
2
A closedform solution for deflections and stresses in an annular thin plate of radially functionally graded material under transverse uniform pressure loading is presented. The small displacement theory of elasticity is assumed in the present work. Young’s modulus of the material is taken in the form of a simple power law to vary in the radial direction with an arbitrary exponent showing heterogeneity of the plate, while Poisson's ratio is held constant throughout the plate. Deflection and stress distributions are graphically presented for various values of the heterogeneity exponent to illustrate its effects on the deflections and stresses. Through the current analysis, this exponent can be adjusted in actual designs to control the deflections and stress levels in a plate.
1
A closedform solution for deflections and stresses in an annular thin plate of radially functionally graded material under transverse uniform pressure loading is presented. The small displacement theory of elasticity is assumed in the present work. Young’s modulus of the material is taken in the form of a simple power law to vary in the radial direction with an arbitrary exponent showing heterogeneity of the plate, while Poisson's ratio is held constant throughout the plate. Deflection and stress distributions are graphically presented for various values of the heterogeneity exponent to illustrate its effects on the deflections and stresses. Through the current analysis, this exponent can be adjusted in actual designs to control the deflections and stress levels in a plate.
41
45


M. H.
Babaei
Iran


M.
Salehi
Iran


R.
Naj
Iran
Annular plate
Functionally Graded Material (FGM)
Analytical Solution
[[1] M.Yamanouchi, M. Koizumi, T. Hirai, and I. Shiota (eds.), Proc. First Int.Sympos, Functionally Gradient Materials, Japan, 1990. ##[2] Melanie P. Lutz, Robert W. Zimmerman, "Thermal stresses and effective thermal expansion coefficient of a functionally graded sphere", J. Thermal Stresses, Vol. 19, 1996, pp. 3954. ##[3] Robert W. Zimmerman, Melanie P. Lutz, "Thermal stresses and thermal expansion in a uniformly heated functionally graded cylinder", J. Thermal Stresses, Vol. 22, 1999, pp. 177188. ##[4] B. V. Sankar, "An elasticity solution for functionally graded beams", J. Composites Science and Technology, Vol. 61, 2001, pp. 686696. ##[5] Naki Tutuncu, Murat Ozturk, "Exact solutions for stresses in functionally graded pressure vessels", J. Composites Part B: Engineering, Vol. 32, 2001, pp. 683686. ##[6] M. Jabbari, S. Sohrabpour, M. R. Eslami, "Mechanical and thermal stresses in a functionally graded hollow cylinder due to radially symmetric loads", Int. J. Pressure Vessels and Piping, Vol. 79, 2002, pp. 493497. ##[7] M. Jabbari, S. Sohrabpour, M. R. Eslami, "General solution for mechanical and thermal stresses due to nonaxisymmetric steadystate loads", ASME J. Applied Mechanics, Vol. 70, 2003, pp. 111118. ##[8] Z.S. Shao, "Mechanical and thermal stresses of functionally graded circular hollow cylinder with finite length", Int. J. Pressure Vessels and Piping, Vol. 82, 2005, pp. 155163. ##[9] J. N. Reddy, C. M. Wang, S., "Kitipornchai. Axisymmetric bending of functionally graded circular and annular plates", Eur. J. Mech. A/Solids, Vol. 18, 1999, pp. 185199. ##[10] J. N. Reddy, C. D. Chin, "Thermomechanical analysis of functionally graded cylinders and plates", J. Thermal Stresses, Vol. 21, 1998, pp. 593626. ##[11] R. Shahsiah, M.R. Eslami, "Thermal instability of functionally graded cylindrical shell based on the improved Donnell equations", AIAA J., Vol. 41(9), 2003, pp. 18191827. ##[12] R. Javaheri, M.R. Eslami, "Thermal buckling of functionally graded plates", AIAA J., Vol. 40(1), 2002, pp. 162169. ##[13] Y. Obata, N. Noda, "Steady thermal stresses in a hollow circular cylinder and a hollow sphere of a functionally graded material", J. Thermal Stresses, Vol. 17, 1994, pp. 471487. ##[14] Y. Ootao, Y. Tanigawa, "Threedimensional transient thermal stresses of functionally graded rectangular plate due to partial heating", J. Thermal Stresses, Vol. 22, 1999, pp. 3555. ##[15] Y. Ootao, Y. Tanigawa, "Threedimensional transient piezothermoelasticity in functionally graded rectangular plate bonded to a piezoelectric plate", Int. J. Solids and Structures, Vol. 37, 2000, pp. 43774401.##]
Water Management in the Cathode Side of a PEM Fuel Cell
Water Management in the Cathode Side of a PEM Fuel Cell
2
2
A one dimensional isothermal mathematical modeling of cathode side of a Proton Exchange Membrane (PEM) fuel cell is developed for the water management problem. Water transport is investigated in both cathode Gas Diffusion Layer (GDL) and membrane through solving appropriate equations for fluid flow and mass transport in GDL and water transport within the membrane. The gaseous mixture flowing in cathode GDL consists of three species: oxygen, water vapor and nitrogen. The model considers one phase flow in the gas diffusion layer and then predicts the regions with possible condensation. Homogenous distribution of wet phase (liquid water) is assumed throughout each wet control volume as fog. The model couples all governing equations in both membrane and GDL using an innovative algorithm. A detailed discussion of numerical techniques for the PEMFC model is given with a flow diagram to provide an overview of the solution procedure. Validation for polarization curve is implemented to show agreement between the obtained results and existing results in the literature.
1
A one dimensional isothermal mathematical modeling of cathode side of a Proton Exchange Membrane (PEM) fuel cell is developed for the water management problem. Water transport is investigated in both cathode Gas Diffusion Layer (GDL) and membrane through solving appropriate equations for fluid flow and mass transport in GDL and water transport within the membrane. The gaseous mixture flowing in cathode GDL consists of three species: oxygen, water vapor and nitrogen. The model considers one phase flow in the gas diffusion layer and then predicts the regions with possible condensation. Homogenous distribution of wet phase (liquid water) is assumed throughout each wet control volume as fog. The model couples all governing equations in both membrane and GDL using an innovative algorithm. A detailed discussion of numerical techniques for the PEMFC model is given with a flow diagram to provide an overview of the solution procedure. Validation for polarization curve is implemented to show agreement between the obtained results and existing results in the literature.
47
54


N.
KhajehHosseini D
Iran


H. R.
Shabgard
Iran


M. J.
Kermaniiii
Iran
PEM fuel cell
Water management
Porous electrode
StefanMaxwell equation
[[1] D. M. Bernardi and M. W. Verbrugge, "Mathematical Model of a Gas Diffusion Electrode Bonded to a Polymer Electrolyte," AIChE J., 37(9), pp.1151–1163, 1991. ##[2] T. E. Fuller and J. Newman, "Water and Thermal Management in SolidPolymerElectrolyte Fuel Cells," J. Electrochem. Soc., 140, pp.1218–1225, 1993. ##[3] T. E. Springer, T. A. Zawodzinski, and S. Gottefeld, "Polymer Electrolyte Fuel Cell Model," J. Electrochem. Soc., 138 (8), pp.2334–2342, 1991. ##[4] L. You and H. Liu, "A TwoPhase and Transport Model for the Cathode of PEM Fuel Cells," Int. J. Heat and Mass Transfer, 45 pp. 2277–2287, 2002. ##[5] M. J. Kermani and J. M. Stockie, "Heat and Mass Transfer Modeling of Dry Gases in the Cathode of PEM Fuel Cells," Int. J. Comp. fluid dyn., 18(2), pp. 153–164, 2004. ##[6] R. E. De la Rue and C. W. Tobias, "On the Conductivity of Dispersions," J. Electrochem. Soc., 106, pp. 827–833, 1959. ##[7] E. L. Cussler, Diffusion Mass Transfer in Fluid Systems, CambridgeUniversity Press, 1984. ##[8] Ugur Pasaogullari, C.Y. Wang and Ken S. Chen. "TwoPhase Transport in Polymer Electrolyte Fuel Cells with Bilayer Cathode Gas Diffusion Media," J. Electrochem. Soc., 152(8), pp. 1574–1582, 2005. ##[9] S. Motupally, A. J. Becker and J. W. Weidner, "Diffusion of Water in Nafion 115 Membranes," J. Electrochem. Soc., 147(9), pp. 3171–3177, 2000. ##[10] Weber, A.Z. and Newman, J., "Modeling Transport in PolymerElectrolyte Fuel Cells", Chem. Rev., 104, pp. 4679–4726, 2004. ##[11] J. Larminie, and A. Dicks, Fuel Cell Systems Explained, John Wiley and Sons, 2001. ##[12] Ticianelli E.A., Derouin C.R., Redondo A., Srinivasan S., "Methods to Advance Technology of Proton Exchange Membrane Fuel Cells" J. Electrochem. Soc. 135 pp. (1988) 2209.##]
Flexural Behavior of Cementitious Composites Reinforced by Synthetic Fibers
Flexural Behavior of Cementitious Composites Reinforced by Synthetic Fibers
2
2
The application of fibers to reinforce cementitious materials is a wellknown subject. At first, asbestos fibers are used in industrial process to produce fiber reinforced cement sheets. Thereafter, various types of synthetic fibers are produced and used as asbestos substitutes. The aim of the present work is to evaluate the effect of synthetic fibers on the flexural behavior of cementitious composites. In this study, the flexural strength of cementbased materials reinforced by three different types of synthetic fibers (polypropylene (PP), polyamide 66 (PA66) and acrylic (PAN)) is studied at various volume contents. It was found that although PAN and PA66 improve maximum flexural load borne by the cementitous composite before failure, the PAN fibers improves toughness of cementitous composites about 30% more than PP and PA66 fibers.
1
The application of fibers to reinforce cementitious materials is a wellknown subject. At first, asbestos fibers are used in industrial process to produce fiber reinforced cement sheets. Thereafter, various types of synthetic fibers are produced and used as asbestos substitutes. The aim of the present work is to evaluate the effect of synthetic fibers on the flexural behavior of cementitious composites. In this study, the flexural strength of cementbased materials reinforced by three different types of synthetic fibers (polypropylene (PP), polyamide 66 (PA66) and acrylic (PAN)) is studied at various volume contents. It was found that although PAN and PA66 improve maximum flexural load borne by the cementitous composite before failure, the PAN fibers improves toughness of cementitous composites about 30% more than PP and PA66 fibers.
55
61


H. R.
Pakravani
Iran


M.
Jamshidiii
Iran


M.
Latifiii
Iran
Flexural behavior
Fiber
Cementitious composites
[[1] A. M. Pye, "A Review of asbestos substitute materials industrial applications", J. Hazard. Mater., vol. 3, pp. 125147, Oct. 1979. ##[2] R. S.P. Coutts,"A review of Australian research into natural fiber cement composites", Cement Concr. Compos., vol. 27, pp.518526, May 2005. ##[3] E. M. Bezerra, A. P. Joaquim, and H. S. Jr., "Some Properties of fiber Cement composites with Selected Fibers", in Proc. 2004 Conferência Brasileira de Materiais e Tecnologias NãoConvencionais – Habitações e Infra Estrutura de Interesse Social, pp. 3343. ##[4] R. F. Zollo, "Fiberreinforced Concrete: an Overview after 30 Years of Development", Cement Concr. Compos., vol. 19, pp. 107122, May 1997. ##[5] B. Felekoğlu, K. Tosun, and B. Baradan, "Effects of fibre type and matrix structure on the mechanical performance of selfcompacting microconcrete composites", Cement Concr. Compos., vol. 39, pp. 10231032, Nov. 2009. ##[6] P. S. Song, S. Hwang, and B. C. Sheu, "Strength properties of nylon and polypropylenefiberreinforced concretes", Cem. Concr. Res., vol. 35, pp. 15461550, Aug. 2005. ##[7] D. j. Kim, A. E. Naaman, and S. ElTawil " Comparative flexural behavior of four fiber reinforced cementitious composites", Cement Concr. Compos., vol. 30, pp. 917928, Nov. 2008.##]