@article { author = {Shokrollahi, A.}, title = {Computation Optical Flow Using Pipeline Architecture}, journal = {International Journal of Engineering}, volume = {11}, number = {4}, pages = {181-190}, year = {1998}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Accurate estimation of motion from time-varying imagery has been a popular problem in vision studies, This information can be used in segmentation, 3D motion and shape recovery, target tracking, and other problems in scene analysis and interpretation. We have presented a dynamic image model for estimating image motion from image sequences, and have shown how the solution can be obtained from a set of partial differential equations. In this paper, we have investigated a relaxation type algorithm for obtaining a numerical solution to these equations, and considered the implementation of the algorithm on a variation of the general pipeline interconnection scheme using transputers. This architecture is compared against two others based on flexibility and efficiency. It is observed that with respect to computation, a mesh connected architecture has advantages over the proposed pipeline scheme. However, the pipeline configuration is easily expandable and more robust to changes in the algorithms parameters and image size.}, keywords = {Vision. Image Motion,Optical Flow,Pipeline,mesh}, url = {https://www.ije.ir/article_71211.html}, eprint = {https://www.ije.ir/article_71211_e01a76242686368f4a29f265b0d8baf9.pdf} } @article { author = {Singh, C. J. and Jain, Madhu}, title = {A Finite Capacity Priority Queue with Discouragement}, journal = {International Journal of Engineering}, volume = {11}, number = {4}, pages = {191-196}, year = {1998}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {In this paper we report on a study of a two level preemptive priority queue with balking and reneging for lower priority level. The inter-arrival and the service times for both levels follow exponential distribution. We use a finite difference equation approach for solving the balance equations of the governing queuing model whose states are described by functions of one independent variable. Hence the balance equations may be viewed as a set of simultaneous difference equations and can be solved by using appropriate techniques.}, keywords = {Queue,Balance Equation,Balking,Reneging,Priority Queue,Markovian Queue}, url = {https://www.ije.ir/article_71212.html}, eprint = {https://www.ije.ir/article_71212_3c1d5850f14673218cefa0744413554f.pdf} } @article { author = {Pishevar, A. R.}, title = {Numerical Simulation of Shock-Wave/Boundary/Layer Interactions in a Hypersonic Compression Corner Flow}, journal = {International Journal of Engineering}, volume = {11}, number = {4}, pages = {197-206}, year = {1998}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Numerical results are presented for the shock-boundary layer interactions in a hypersonic flow over a sharp leading edge compression corner. In this study, a second- order Godunov type scheme based on solving a Generalized Riemann Problem (GRP) at each cell interface is used to solve thin shear layer approximation of laminar Navier-Stokes (N-S) equations. The calculated flow-field shows general agreement with the experimental data. The heat transfer coefficient and the extent of the separation are predicted with an adequate accuracy. Furthermore, the effects of the employed slope-limiter on the present computations are addressed.}, keywords = {TVD Scheme,Slope,Limiter,Generalised Riemann Problem,Compression Corner Flow}, url = {https://www.ije.ir/article_71213.html}, eprint = {https://www.ije.ir/article_71213_9207396cfa980729a115bb238c43a3ce.pdf} } @article { author = {Mireshghi, M.}, title = {Simulation of a Neutron Detector for Real Time Imaging Applications}, journal = {International Journal of Engineering}, volume = {11}, number = {4}, pages = {207-212}, year = {1998}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Monte Carlo Method is used to simulate a double layer gadolinium-amorphous silicon thermal neutron detector. The detector fabricated in pixel array configuration has various applications including neutron imaging. According to the simulation results, a detector consisting of a gadolinium (Gd) film with thickness of 2-4 ~m, sandwiched properly with two layers of sufficiently thick (-30 ?µm) hydrogenated amorphous silicon (a-Si:H) diodes would have the optimum characteristics. At a threshold setting of ~7000 electrons, the detectors would have efficiency of about 42%. The expected average signal size is about 12000 electrons, which is well above the noise. These neutron detectors have very low gamma sensitivity and are very well suited to real time neutron imaging applications. A}, keywords = {Neutron Detector,Imaging,Monte Carlo,a,SiH}, url = {https://www.ije.ir/article_71214.html}, eprint = {https://www.ije.ir/article_71214_1484611a659ac476eda878f8ee95db8c.pdf} } @article { author = {Dehghanian, R.}, title = {Evidence of the Potential Shift Mechanism in Crevice Corrosion (RESEARCH NOTES)}, journal = {International Journal of Engineering}, volume = {11}, number = {4}, pages = {213-218}, year = {1998}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Previous research has indicated a qualitative resemblance between the current distribution along actively corroding crevice walls and currents measured in corresponding anodic polarization plots. Using detailed measurements of the potential gradient along the crevice, a semi-quantitative current distribution was calculated for the crevice wall using a double numerical differentiation method. The calculated current distribution was found to approximate that of the active loop measured in independent anodic polarization tests of the free metal surface.}, keywords = {Crevice,Potential,corrosion,Current Distribution,Double Numerical Differentiation,polarization}, url = {https://www.ije.ir/article_71215.html}, eprint = {https://www.ije.ir/article_71215_f13e395cd97c39ea43aa75118a129e1e.pdf} } @article { author = {Sinaie, A.}, title = {Tomographic Determination of Temperature Distribution in Billets (RESEARCH NOTES)}, journal = {International Journal of Engineering}, volume = {11}, number = {4}, pages = {219-228}, year = {1998}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {The principles of Ultrasonic Computed Tomography (UCT) are reviewed in this paper. The UCT is a powerful nondestructive technique in medicine and recently in industry to reveal an image of a slice of an object or body. The advantage of UCT over other conventional techniques in imaging is that a computed tomogram yields quantitative information about the section of interest. Experimental works on obtaining a tomogram of the temperature distribution in the mid-section of a block of an aluminum alloy utilizing the available simple equipment are carried out. A discussion of the analysis and results is presented. Certain modifications are also suggested to improve the accuracy and reproducibility of the results. A}, keywords = {Tomography,temperature distribution,NDT&E}, url = {https://www.ije.ir/article_71216.html}, eprint = {https://www.ije.ir/article_71216_ba022a0e066fc1301281b259b52ddb90.pdf} } @article { author = {Sadr Karimi, Jamshid}, title = {Lime and Distilled Water Treatment of Dispersive Soils by Electroosmosis Effect (TECHNICAL NOTE)}, journal = {International Journal of Engineering}, volume = {11}, number = {4}, pages = {229-234}, year = {1998}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {This paper explains the procedure and results of electro osmosis treatment of a dispersive soil. A number of cylindrical specimens of a dispersive soil were subjected to the electro osmosis effect and the subsequent cation changes in the soil, inlet water and outlet water were measured. The tests were carried out using distilled water and lime extract in anode. It was observed that with distilled water the TDS and percent sodium values decrease both in the soil adjacent to the anode and the cathode electrodes. This proves a considerable migration of cations due to the electro osmosis effect. In a limited period of treatment, using distilled water, the dispersivity is treated in soil close to anode while increases in soil close to cathode. However, in long term, the effect may be partially reversible. Less efficiency is obtained with lime extract in a limited period of treatment. Probably if a long term treatment with a lower voltage had been carried out a better effect would have resulted. However, further investigations are needed.}, keywords = {Electro osmosis,Dispersivity,Sodium Adsorption,Percent Sodium,Pinhole Test}, url = {https://www.ije.ir/article_71217.html}, eprint = {https://www.ije.ir/article_71217_b97db795d579246cf2b0384a0d8051e8.pdf} }