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1
Content available remote ANAFIS and neural network for modeling and prediction of ship squat in shallow waters: a new approach
Zeraatgar H., Akbari Vakilabadi K., Salmalian K., Haghi A. K.
International Journal of Applied Mechanics and Engineering
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2011
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Vol. 16, no 1
211-231
EN
The reduction of the distance between ship floor and seabed, while the ship is moving forward, is called squat. In this research, squat is determined for vessels with Series-60 hull forms in various depths by experimental methods and then different numerical methods are employed for squat modeling. For this reason, a set of facilities for testing the ship movement in shallow waters is prepared. A series of models of the vessel is manufactured and many tests are carried out. The aim of the present study is to demonstrate the usefulness of an adaptive-network-based fuzzy inference system (ANFIS) for modeling and predicting the squat parameter for ships in shallow waters. It is also shown how dimensionless squat (S*) varies with the variation of important parameters, namely: block coefficient (CB), dimensionless distance between the seabed and ship floor […] and hydraulic Froude Number (Fnh). The results obtained through the ANFIS are also compared with those of a multiple linear regression and GMDH-type neural network with multi-layered feed forward back propagation algorithm. The results show that the ANFIS-based squat has higher predictability function than other numerical methods.
2
Content available remote Post buckling modelling and optimization of sandwich panels with corrugated cores
Gorji M., Ashouri D., Asadi H., Haghi A. K.
International Journal of Applied Mechanics and Engineering
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2009
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Vol. 14, no 4
949-964
EN
In the present study, analytical expressions for critical loads are derived and eigenvalue and post buckling analyses are performed on the panels, using the finite element method, and the commercial software ABAQUS. A genetic algorithm is used for optimization of sandwich panels with periodic, open-cell cores. Yielding and buckling in components are treated as optimization constraints. Then minimum weights for some load capacities are determined. Design variables and cost function are defined as non-dimensional and optimal results are shown by diagrams.
3
Content available remote Mechanical properties of cement based composite containing Rice-Husk Ash
Sadrmomtazi A., Haghi A. K.
International Journal of Applied Mechanics and Engineering
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2009
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Vol. 14, no 2
501-508
EN
Different mix designs of cement based composites with a varying amount of rice-husk ash as a pozzolan, water-cement ratio and super plasticizer were investigated. Composite properties were then studied using the Slump-Flow test, L-Box test, V-Funnel test in order to evaluate bleeding, resistance to segregation and workability. The physical and mechanical properties of Self-Compacting Concrete (SCC) were studied and compared with a reference normal concrete (NC). 48 cubic moulds were made and their compressive strength at the ages of 3, 7, 14, 28, 60, 90 and 120 days determined. In this survey to determine tensile strength, shrinkage and modulus of elasticity, 12 prismatic moulds, 6 prismatic and 3 cylinders moulds were prepared. These samples cured in three different environmental conditions such as water, humidity and air. The results show higher compressive strength in SCC, while shrinkage does not differ from that of NC. We found that the modulus of elasticity and Poisson's ratio are slightly improved in SCC.
4
Content available remote Mechanical properties of a cement based composite containing lime-stone powder
Sadrmomtazi A., Haghi A. K.
International Journal of Applied Mechanics and Engineering
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2008
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Vol. 13, no 4
1133-1138
EN
This article outlines an experimental study on different properties such as compressive strength, tensile strength; modulus of elasticity and shrinkage of SCC (Self-Compacting Concrete) containing milled limestone powder. The results show that shrinkage in SCC is approximately twice more than that of normal concrete, while elastic modulus, compressive and tensile strength do not differ significantly.
5
Content available remote Investigation on the influence of the electron radiation on the appearance of fibers
Mohammadi K., Haghi A. K.
International Journal of Applied Mechanics and Engineering
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2007
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Vol. 12, no 3
875-877
EN
In this paper, the influences of electron radiation on the appearance of microwave-dried fibers were studied. Previously dried fibers with different properties are radiated by the electron beam of an electron microscope. Variable magnifications, processing time and voltage are applied. Using electron microscopy photographs, fibers inflations or deflations are measured precisely. It is observed that the electron energy can have significant effects on the fibers surface layer properties.
6
Content available remote A study on thermal drying of wood
Haghi A. K., Haghi R. K.
International Journal of Applied Mechanics and Engineering
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2007
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Vol. 12, no 3
865-873
EN
Drying is a complex operation involving transient transfer of heat and mass along with several rate processes, such as physical or chemical transformations, which in turn, may cause changes in product quality. This article surveys the impacts of convective, infrared and microwave drying on the strength of dried wood. The effects of drying methods on mechanical properties have been studied for many materials, but wood products have seldom been the subject. Spruce wood samples (length = 140 mm and diameter = 21.0 mm) were dried using the following drying regimes: convective (1000 C and 400 C), microwave (480, 790, and 1000 W power) and infrared (100% power). The dried sampies were then subjected to tensile loading in order to evaluate the mechanical properties. It is concluded that the microwave drying can improve the strength of dried samples significantly.
7
Content available remote Experimental study on combined infrared and microwave drying of porous media with particular application in wood industry
Haghi A. K., Ghanadzadeh H.
International Journal of Applied Mechanics and Engineering
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2006
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Vol. 11, no 4
985-991
EN
Porous materials such as wood have microscopic capillaries and pores which cause a mixture of transfer mechanisms to occur simultaneously when subjected to heating. Infrared and microwave heating of wood products has not been used to a larger extent by the wood industries and manufactures. This could be explained by the insufficient knowledge of the complex interaction between a porous material and process parameters during drying. This article uses the drying experiments to study the effects of drying modes, density and moisture content on wood hardness. Brinell hardness is measured on wood surfaces of Guilan spruce at two angles to the grain.
8
Content available remote Experimental survey on heat and moisture transport through fabrics
Haghi A. K.
International Journal of Applied Mechanics and Engineering
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2005
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Vol. 10, no 2
217-226
EN
Heat and moisture transport processes occurring within the solid matrix and in the voids are complicated even for a regularly shaped matrix and impossible for the irregular shaped configurations that exist in general, in porous media. The aim of this article is to contribute to the understanding of the behavior of fabric during dynamic moisture and heat transfer with particular reference to clothing comfort and to review the latest developments.
9
Content available remote A theoretical approach to the solutions of surface irregularities parameters
Haghi A. K.
International Journal of Applied Mechanics and Engineering
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2005
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Vol. 10, no 2
359-364
EN
In this paper, the probability characteristics of surface irregularities parameters described by the composition of the deterministic component and the homogeneous random normal field were analysed. Formulae for the calculation of the mathematical expectation of the Ras parameter and the evaluation of its variance are given.
10
Content available remote The diffusion of heat and moisture through textiles
Haghi A. K.
International Journal of Applied Mechanics and Engineering
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2003
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Vol. 8, no 2
233-243
EN
An improved mathematical model that takes into account the water vapor sorption mechanisms of wool fiber is developed to describe and predict the coupled heat and moisture transport in wool fabrics.On the basis of the model, the moisture-sorption mechanisms are investigated for fabrics made from fibers with different degrees of hygroscopicity. Theoretical predictions on the moisture uptake and temperature changes under humidity transients are compared with those measured previously in a sorption-cell experiment for fabrics made from wool, cotton, acrylic fiber, and polypropylene fiber. It is concluded that the physical mechanism of moisture diffusion into highly hygroscopic fibers such as wool and cotton can be described by a two stage moisture diffusion process.
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