@article { author = {Sadrnejad, S. A.}, title = {A Multi Plane Model for Natural Anisotropy of Sand}, journal = {International Journal of Engineering}, volume = {16}, number = {4}, pages = {311-327}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Anisotropy of sand is mainly due to the geometrical arrangement of particles that depends on the orientation of applied load respect to the bedding plane. It is geologically due to micro-fabric created by the arrangement of the particles configured during deposition. Most of the models develop using stress/strain invariants are not capable of identifying this kind of anisotropy. This is mainly because stress/strain invariants are quantities not capable of carrying directional information with them selves. The main objective of this paper is to outline a methodology for modeling the elastic-plastic behaviour of an inherently anisotropy arising from certain kind of plane of deposition. The constitutive equations of the model are derived within the context of elastic behaviour of the whole medium and plastic sliding of interfaces of predefined multi-planes, following the framework of working with six stress/strain components and not missing the directional effects. The formulation incorporates explicity the notion of the preferred direction, which defines the orientation of the material fabric. The proposed multi-plane based model is capable of predicting the behaviour of soils on the basis of plastic sliding mechanisms, elastic behaviour of particles and possibilities to see the micro-fabric effects as natural anisotropy as well as induced anisotropy in plasticity. The model is capable of predicting the behaviour of soil under different orientation of bedding plane, history of strain progression stress and strain axes and induced anisotropy are include in a rational way without any additional hypotheses. The spatial strength distribution at a an approximation of probable mobilized sliding mechanism is proposed as a ellipsoid function built up on bedding plane.}, keywords = {multi,plane,Elastic,Plastic,model,Anisotropy,Bedding Plane}, url = {https://www.ije.ir/article_71466.html}, eprint = {https://www.ije.ir/article_71466_070274cd3392256aef15e8f80c1f61b6.pdf} } @article { author = {Eslambolchi, P. and HoseinNezhad, Reza and Moshiri, B.}, title = {Fuzzy Clustering Approach Using Data Fusion Theory and its Application To Automatic Isolated Word Recognition}, journal = {International Journal of Engineering}, volume = {16}, number = {4}, pages = {329-336}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = { In this paper, utilization of clustering algorithms for data fusion in decision level is proposed. The results of automatic isolated word recognition, which are derived from speech spectrograph and Linear Predictive Coding (LPC) analysis, are combined with each other by using fuzzy clustering algorithms, especially fuzzy k-means and fuzzy vector quantization. Experimental results show that the proposed algorithms have better performance, compared to classical clustering.}, keywords = {Data Fusion Theory,K,Means Clustering,Fuzzy K,Means,Fuzzy Vector Quantization}, url = {https://www.ije.ir/article_71468.html}, eprint = {https://www.ije.ir/article_71468_a06fcbfb73a004d8fad65010e5b8e51c.pdf} } @article { author = {Cheldavi, A. and Danaei, M. M.}, title = {Capacitive Flux Compression Generator (RESEARCH NOTE)}, journal = {International Journal of Engineering}, volume = {16}, number = {4}, pages = {337-348}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Conventional Flux Compression Generators (FCG's) are used to generate high power DC pulses. A new kind of (FCG's) with series capacitance called Capacitive Flux Compression Generator (CFCG) will be introduced and explained in this paper. This new kind is used to generate modulated high power pulses. There are some problems to establish a capacitance in high power and high frequency applications. In the present paper several practical methods will be addresed to make capacitance in high power and high frequency applications.}, keywords = {Flux Compression Generator,High Power Sources,High Frequency Sources}, url = {https://www.ije.ir/article_71470.html}, eprint = {https://www.ije.ir/article_71470_dd0b2b9da77caf2ab44f9d708c37a026.pdf} } @article { author = {Saeri, M.R. and Ehsani, N. and Ghorbani, Mohammad and Afshar, A. and Sorrell, C. C.}, title = {A Study of Zeta Potential of Plasma Sprayed Hydroxyapatite Coating in Four Simulated Physiological Solutions}, journal = {International Journal of Engineering}, volume = {16}, number = {4}, pages = {343-354}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {The zeta potential magnitude and the duration of its changes have been thought to be directly related to the surface reactivity, the governing of osteoconductivity and availability of valuable information in determining the anticipated in-vivo performance of implants. In this study the zeta potential of plasma sprayed hydroxyapatite (HA) was evaluated in various simulated physiological solutions. For this purpose the prepared samples were immersed in SBF, Ringers, Tyrodes and Hanks solutions for 3 weeks and kept at 37°C and the time dependent variations of zeta potential results were compared with calcined (2 hr at 850°C) and as-precipitated HA powders. Furthermore, following immersion test, the coating surfaces were examined with SEM and XRD as well as FTIR methods. The results showed that in majority of solutions, the zeta potential increased in the following order: calcined, as precipitated and plasma sprayed. Moreover, the ion concentrations and types in the solutions have significant effects on the zeta potential values. Following the immersion test, the morphology of the samples were determined a function of the thermal history of HA, duration of immersion and the type of the test solution. The results indicated that the surface of the HA coated samples were unstable with significant changes in the observed charge.}, keywords = {Hydroxyapatite,Zeta potential,Plasma spray coat,corrosion}, url = {https://www.ije.ir/article_71471.html}, eprint = {https://www.ije.ir/article_71471_1d0d6243ee4512fd63a5edca7119b092.pdf} } @article { author = {Javadpour, J. and Yusefi, A.}, title = {Effect of Sintering Conditions on Microstructure and the Superconducting Properties of YBa2Cu3O7 x}, journal = {International Journal of Engineering}, volume = {16}, number = {4}, pages = {355-360}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {YBa2Cu3O7-X tapes fabricated from precursor powder, were used to investigate the effect of sintering conditions on the microstructure. The sintering experiments were carried out in oxygen over the temperature range of 915-950ْC. Scanning electron microscopy was used to examine the sintered products. The result indicated a significant increase in densification and grain growth when the tapes were heat treated above 915ْC. The critical current density in the sintered tapes showed deteriotation when the sintering was done at temperatures above 915ْC.}, keywords = {Superconductor,YBa2Cu3O7,X,D.C. Susceptibility,Critical Current Density,Microstructure}, url = {https://www.ije.ir/article_71473.html}, eprint = {https://www.ije.ir/article_71473_926db16b1c3f7d0e3c5a031b53a5a08b.pdf} } @article { author = {Nemati, A. and Poya-Mehr, M. R.}, title = {Effects of Aluminum, Silicon And Ferro Silicon Anti Oxidants in MgO C Refractories}, journal = {International Journal of Engineering}, volume = {16}, number = {4}, pages = {361-372}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {  Three different materials (aluminum, ferro -silicon and silicon) were used as antioxidants in order to prevent the decarburization process and to keep and/or increase the final properties in MgO-C refractories. Their effects were compared by measuring the physical and mechanical properties as well as oxidation and the resultant phases and microstructures, in the temperature range of 200-1600 °C. High temperature oxidation was measured up to 1000 °C. The impurities of the aluminum and silicon powders were less than 1%. The ferro-silicon contains 2-5% Al, and 10-20% Fe. Results indicate that the oxidation of the samples were much better in the ferrosilicon than aluminum and silicon cases. The CCS measurements indicate more improvements due to the effects of ferro-silicon than silicon case. Results indicate that aluminum is more effective at low temperature. However, at higher temperatures, the other two anti-oxidants are more effective. The phase analysis indicates that the reaction of M2S phase with other phases might cause some reduction of high temperature behaviors. Also, Phase analysis indicates the formation of MgO-FeO/Fe2O3 phase, aluminum and silicon carbides as well as Spinel phase in the samples.}, keywords = {MgO,C Refractory,anti,Oxidants,Aluminum,Silicon,Ferro}, url = {https://www.ije.ir/article_71475.html}, eprint = {https://www.ije.ir/article_71475_0fb095b38a681ca744dce25a0d97fed4.pdf} } @article { author = {Eghtesad, M. and Lotfazar,, A. and Mohseni, M.}, title = {Integrator Backstepping Control of a 5 DoF Robot Manipulator with Cascaded Dynamics}, journal = {International Journal of Engineering}, volume = {16}, number = {4}, pages = {373-383}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {In this paper, dynamic equations of motion of a 5 DoF robot manipulator including mechanical arms with revolute joints and their electrical actuators are considered. The application of integrator backstepping technique for trajectory tracking in presence of parameters of uncertainty and disturbance is studied. The advantage of this control technique is that it imposes the desired properties of stability by fixing the candidate Lyapunov functions initially, then by calculating the other functions in a recursive way. Simulation results are presented in order to evaluate the tracking performance and the global stability of the closed loop system. The validity and usefulness of the proposed technique for robot motion control when the system dynamics including both mechanical arms and electrical actuators become more complex is obtained from the results.}, keywords = {Integrator Backstepping Control,Actuators Dynamics,5 DoF Robot Manipulator,Robot Control}, url = {https://www.ije.ir/article_71477.html}, eprint = {https://www.ije.ir/article_71477_714a9410dcc4305c56a766f8937359c9.pdf} } @article { author = {Haghighat, H. and Sadeghi, M. H.}, title = {An Instantaneous Rigid Force Model For 3-Axis Ball-End Milling Of Sculptured Surfaces}, journal = {International Journal of Engineering}, volume = {16}, number = {4}, pages = {385-394}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {An instantaneous rigid force model for prediction of cutting forces in ball-end milling of  sculptured surfaces is presented in this paper. A commercially available geometric engine is used to represent the cutting edge, cutter and updated part geometries. The cutter used in this work is an insert type ball-end mill. Intersecting an inclined plane with the cutter ball nose generates the cutting edge. Immersion geometry along the tool path is computed using the contact face between the ball-end mill and the solid model of the updated part. The engaged portion of the cutting edge is divided into small differential oblique cutting edge segments. Friction, shear angles and shear stresses are obtained from orthogonal cutting data available in the open literature. For each tool rotational position, the cutting force components are calculated by summation of the differential cutting forces. The developed model has been verified through experiments performed on several workpieces with different front and side angles. The predicted cutting forces have shown good agreement with experimental results. The developed model can be used as an efficient tool for predicting cutting performance in ball-end milling of sculptured surfaces of dies and moulds.}, keywords = {Ball,End Milling,Cutting force,Die and Mould Machining}, url = {https://www.ije.ir/article_71480.html}, eprint = {https://www.ije.ir/article_71480_2039412ab151bd7e078c5b1088be0ae9.pdf} } @article { author = {Gharehaghaji, A. A. and Forughi, J.}, title = {Study on the Interactions between Mechanical and Structural Properties of the Thermobonded Nonwovens}, journal = {International Journal of Engineering}, volume = {16}, number = {4}, pages = {395-406}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Thermobonding is widely used in producing of nonwovens. In this study various layers of thermobonded nonwovens were produced by altering the pressure, binder fibres and quality of blending. Mechanical properties of the so-called layers such as breaking strength and breaking elongation, bending rigidity and air permeability were assessed consequently. The structure of the layers was then studied by scanning electron microscope (SEM) and the interaction between the structure and mechanical properties and failure mechanism of the layers was investigated. This study shows that the interstructure appears in the form of point structure and agglomerate structure when bicomponent PET and PP fibers were used as the binder respectively. The detrimental effect of the interstructure on the mechanical behavior of layers was spotted during the experiments. The results indicate that the magnitude of the pressure, the type of the binder fibre and stages of blending affect the interstructure enormously. SEM examination of the fractured ends of the layers after stretching could assess the likely mechanism of failure of layers formed by bicomponent PET binder and polypropylene binder fiber.}, keywords = {Thermal Bonding,Interstructure,Binder Fiber,Mechanical Behavior,SEM}, url = {https://www.ije.ir/article_71482.html}, eprint = {https://www.ije.ir/article_71482_23b86319d96361e355c0824b3d0190de.pdf} }