Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 A Numerical Study of Chamber Size and Boundary Eects on CPT Tip Resistance in NC Sand 2911 EN M.M. Ahmadi Department of Civil Engineering,Sharif University of Technology P.K. Robertson Department of Civil and Environmental Engineering,University of Alberta Journal Article 2009 05 20 A numerical modeling procedure was used to quantify calibration chamber size and boundary eects for cone penetration testing in sand. In the numerical analyses, chamber diameter and boundary conditions were varied to investigate the eects of chamber size and boundary conditions on cone tip resistance. These analyses show that, for loose sand, a chamber-tocone diameter ratio of 33 is sucient for the boundaries to have no in uence on the cone tip measurements. However, for very dense sand, the numerical analyses show that the chamberto- cone diameter ratio should be more than 100 to ensure that boundaries have no in uence on cone tip measurements. Numerical analysis indicates that, not only the sand relative density but its stress state is also a signicant factor in in uencing the chamber size eects. The results of the numerical analyses were compared to existing empirically based relationships. Suggestions are provided to reduce the eects of chamber size and boundaries on cone tip resistance measurements in sand. https://scientiairanica.sharif.edu/article_2911_ef67f7c2d86352c2c42e19d20f881f53.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 Generation of Orthoimage from High-Resolution DEM and High-Resolution Image 2912 EN M. Saati Department of Geomatics Engineering,University of Tehran J. Amini Department of Geomatics Engineering,University of Tehran Journal Article 2009 05 25 Generating an orthoimage from high-resolution satellite images is an important undertaking for various remote sensing and photogrammetric applications. In this paper, a method is proposed that uses Articial Neural Networks (ANN) to generate orthoimage Ikonos Geo images. For orthoimage generation, a Digital Elevation Model (DEM) with a cell size of 4 m and RMS error of 0.24 m is constructed with neural networks, based on a Quad Tree (QT) structure. In order to determine object-to-image relationships, rational function models, polynomials and neural networks with back propagation learning algorithms were used. Ground Control Points (GCPs) and check points were taken from topographic maps of 1:2000, with a contour interval of 2.5 m, to evaluate the accuracy of DEM and object-to-image transformations. The method described in this paper is tested with an Ikonos Geo image from a region of Bilesavar, Iran. https://scientiairanica.sharif.edu/article_2912_c68c9c8258ea7d85472dd6fd0015f047.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 Some New Robust Pseudo Forward and Rotation Gaits for the Snakeboard 2913 EN M. Mahzoon Department of Mechanical Engineering,Shiraz University A. Asnafi Department of Mechanical Engineering,Yasouj University Journal Article 2009 05 25 The goal of this paper is to introduce some new robust gaits of the snakeboard. This is achieved by dening two parameters; the ratios of the frequencies and amplitudes of the snakeboard's sinusoidal shape variable dynamics, and properly adjusting their variations. The gaits are produced via stable and/or moving limit cycles. The highly symmetric patterns generated by these gaits, besides their inherent beauty and coherency, exemplify the rich information content of the underlying nonlinear system. https://scientiairanica.sharif.edu/article_2913_b31df16a88ce00fed951f24b46e08649.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 An Inverse Problem Method for Gas Temperature Estimation in Partially Filled Rotating Cylinders 2914 EN M.M. Heydari Department of Mechanical Engineering,Sharif University of Technology B. Farhanieh Department of Mechanical Engineering,Sharif University of Technology Journal Article 2009 05 25 The objective of this article is to study gas temperature estimation in a partially lled rotating cylinder. From the measured temperatures on the shell, an inverse analysis is presented for estimating the gas temperature in an arbitrary cross-section of the aforementioned system. A nite-volume method is employed to solve the direct problem. By minimizing the objective function, a hybrid eective algorithm, which contains a local optimization algorithm, is adopted to estimate the unknown parameter. The measured data are simulated by adding random errors to the exact solution. The eects of measurement errors on the accuracy of the inverse analysis are investigated. Two optimization algorithms are used in determination of the gas temperature. The conjugate gradient method is found to be better than the Levenberg-Marquardt method, since the former produces more accurate results for the same measurement errors. A good agreement between the exact value and the estimated result has been observed for both algorithms. https://scientiairanica.sharif.edu/article_2914_17eb7ecc4c38e4705361cccd903ad8c6.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 Characteristic Variables and Entrainment in 3-D Density Currents 2915 EN B. Firoozabadi Department of Mechanical Engineering,Sharif University of Technology Journal Article 2009 05 25 A CFD code has been developed to describe the salt solution density current, which propagates three-dimensionally in deep ambient water. The height and width of the dense layer are two dominated length scales in a 3-D structure of the density current. In experimental eorts, it is common to measure the height and width of this current via its brightness. Although there are analytical relations to calculate the current height in a two-dimensional ow, these relations cannot be used to identify the width and height of a 3-D density current, due to the existence of two unknown parameters. In the present model, the height and width of the dense layer are obtained by using the boundary layer concept. Also, a comparison is made between depth averaged and characteristic variables. Then, the computed velocity and concentration proles are compared with the experimental data and the results show good agreement between them. In this work, the entrainment coecient was also calculated using depth-averaged parameters and compared with the experimental data. The result has the same trend as the Ellison and Turner experiments. Present results show that the boundary layer concept can be useful in identifying the height and width of a 3-D density current. https://scientiairanica.sharif.edu/article_2915_e924517087669cf201ea91bd737a4ff4.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 Three-Dimensional Data Transfer Operators in Plasticity Using SPR Technique with C0, C1 and C2 Continuity 2916 EN S.A. Gharehbaghi Department of Civil Engineering,University of Tehran A.R. Khoei Department of Civil Engineering,Sharif University of Technology Journal Article 2009 05 26 In this paper, the data transfer operators are developed in three-dimensional elasto-plasticity using the Superconvergent Patch Recovery (SPR) method. The transfer operators are dened for mapping of the state and internal variables between dierent meshes. The internal variables are transferred from Gauss points of old mesh to the nodal points. The variables are then transferred from the nodal points of old mesh to the nodal points of new mesh. Finally, the values are computed at the Gauss points of new mesh using their values at the nodal points. Aspects of the transfer operators are presented in a three-dimensional superconvergent path recovery technique, based on C0, C1 and C2 continuity. Finally, the eciency of the computational algorithms is demonstrated using a circular tube subjected to internal pressure. https://scientiairanica.sharif.edu/article_2916_340a39045c40d50dda207bcfdece883a.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 Uniform Fractional Part: A Simple Fast Method for Generating Continuous Random Variates 2917 EN H. Mahlooji Department of Industrial Engineering,Sharif University of Technology A. Eshragh Jahromi Department of Industrial Engineering,Sharif University of Technology Journal Article 2009 05 26 A known theorem in probability is adopted and through a probabilistic approach, it is generalized to develop a method for generating random deviates from the distribution of any continuous random variable. This method, which may be considered as an approximate version of the Inverse Transform algorithm, takes two random numbers to generate a random deviate, while maintaining all the other advantages of the Inverse Transform method, such as the possibility of generating ordered as well as correlated deviates and being applicable to all density functions, regardless of their parameter values. https://scientiairanica.sharif.edu/article_2917_dfb84a11f431c62436cfb760e30a34fe.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 Applying Circular Coloring to Open Shop Scheduling 2918 EN M. Modarres Department of Industrial Engineering,Sharif University of Technology M. Ghandehari Department of Industrial Engineering,Sharif University of Technology Journal Article 2009 05 26 IN this paper, a new approach to formulate a class of scheduling problems is introduced, which can be applied to many other discrete problems with complicated structures. The concept of graph circular coloring is applied to develop a model for the special case of an open shop scheduling problem. In this problem, there are some independent jobs to be processed in a shop with dedicated renewable resources. Each job consists of several tasks with no precedence restriction. Each task is processed without preemption. The processing time of the tasks is given. Processing each task requires using some multiple specied types of resource, while no more than one task can use each resource, simultaneously. Some tasks can be shared by more than one job and the process may be repeated more than once. The objective is to develop a schedule which yields the minimal makespan length of all jobs, as well as the number of cycles. The model is rst developed for cases when the processing time of each task is one unit and, then, it is generalized by relaxing this restriction. In both cases, a circular coloring formulation is shown in comparison with traditional formulation (single process execution) results in an improved makespan and also the required information regarding the optimum number of cycles to repeat the process. https://scientiairanica.sharif.edu/article_2918_f6c9dc70ecfd8f90ba8598aa2401cd1a.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 Source Parameters of the March 31st, 2006, Dorud Earthquake in Iran 2919 EN M. Mostafazadeh -------,IIEES Journal Article 2009 05 26 The occurrence of the western Iran earthquake of 31 March 2006 provided an important opportunity to study the source properties of earthquakes in this region. Although moderate in size (ML = 6:1, IIEES), this earthquake was the largest to have occurred in the region since the deployment of the Global Digital Seismograph Network. The far-eld data determination of body wave (P) spectra, interpreted in terms of the circular seismic source model, are used to estimate the parameters seismic moment (MO), corner frequency (f0) , source radius (r) and stress drop (). P waves recorded at teleseismic distances can be obtained from stations of this network that are at to displacement, in a frequency range of 0.19 to 0.32 Hz. The average seismic moment (MO = 14:92 1019 N-M) and source radius (r = 9281 m) were calculated from the long period spectral levels, which were corrected for the radiation pattern of a double couple point source. In addition, the stress drops ( = 87106 N/m2) of this event have been calculated by using an average seismic moment and source radius. Additional errors in the stress drop determination are produced by uncertainty in the seismic moment. Scatter in the seismic moment values is caused by such factors as site condition and errors in the radiation pattern. https://scientiairanica.sharif.edu/article_2919_6271faadeedd7626d661856b7a004e27.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 Numerical Modeling of Hydraulic Fracturing in Oil Sands 2920 EN A. Pak Department of Civil Engineering,Sharif University of Technology 0000-0001-8139-2488 D.H. Chan School of Civil and Environmental Engineering,University of Alberta Journal Article 2009 05 26 Hydraulic fracturing is a widely used and ecient technique for enhancing oil extraction from heavy oil sands deposits. Application of this technique has been extended from cemented rocks to uncemented materials, such as oil sands. Models, which have originally been developed for analyzing hydraulic fracturing in rocks, are in general not satisfactory for oil sands. This is due to a high leak-o in oil sands, which causes the mechanism of hydraulic fracturing to be dierent from that for rocks. A thermal hydro-mechanical fracture nite element model is developed, which is able to simulate hydraulic fracturing under isothermal and non-isothermal conditions. Plane strain or axisymmetric hydraulic fracture problems can be simulated by this model and various boundary conditions, such as specied pore pressure/ uid ux, specied temperature/heat ux, and specied loads/traction, can be modeled. The developed model has been veried by comparing its results to existing analytical and numerical solutions for thermoelastic consolidation problems. The model has been used to simulate a laboratory experiment of hydraulic fracture propagation in oil sands. The results from the numerical model are in agreement with experimental observations. The numerical model and laboratory experiments both indicate that, for uncemented porous materials, such as sands (as opposed to rocks), a single planar fracture is unlikely to occur and a system of multiple fractures or a fracture zone consisting of interconnected tiny cracks should be expected. https://scientiairanica.sharif.edu/article_2920_465636eb4a7ff4b267f3b765d07a02da.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 Time-Domain Analysis of Sandwich Shells with Passive Constrained Viscoelastic Layers 2921 EN M. Salehi Department of Mechanical Engineering,Amirkabir University of Technology F. Bakhtiari-Nejad Department of Mechanical Engineering,Amirkabir University of Technology A. Besharati -------,Iran Aerospace Industries Organization Journal Article 2009 05 26 Damping eects on THE vibration behavior of a sandwich cylindrical shell with a passive constrained viscoelastic layer are investigated in the time-domain. Equations of motion in terms of transverse modal coordinates in the frequency-domain are obtained by means of an energy method and the Lagrange equation, and they are solved by the assumed-mode method. The viscoelastic behavior is represented by the frequency complex modulus model. The equations of motion are transferred from the frequency-domain to the time-domain by the Inverse Fast Fourier Transform, (IFFT). Thickness eects of constrained and viscoelastic layers are investigated by a transient external load response and evaluation of the damping factor and settling time. https://scientiairanica.sharif.edu/article_2921_17d8da815fa21c57af9829fb0a869602.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 Application of a Kinematics-Driven Approach in Human Spine Biomechanics During an Isometric Lift 2922 EN M. Parnianpour Department of Mechanical Engineering,Sharif University of Technology A. Shirazi-Adl Department of Mechanical Engineering,École Polytechnique Journal Article 2009 05 26 Eective prevention and treatment management of spinal disorders can only be based on accurate estimation of muscle forces and spinal loads during various activities such as lifting. The infeasibility of experimental methods to measure muscle and spinal loads has prompted the use of biomechanical modeling techniques. A major shortcoming in many previous and current models is the consideration of equilibrium conditions only at a single cross section, rather than along the entire length of the spine, when attempting to compute muscle forces and spinal loads. The assumption of extensor global muscles with straight rather than curved paths and of the spinal segments as joints with no translational degrees-of-freedom, are additional issues that need to be critically evaluated when simulating lifting tasks. The kinematics-driven approach, which satises equilibrium conditions in all spinal directions and levels and yields spinal postures compatible with external loads, muscle forces and nonlinear passive properties, while also taking into account the wrapping of trunk muscles, is employed. Results demonstrate that, regardless of the method used (optimization or EMG-assisted), single-level free body diagram models yield estimations that grossly violate equilibrium at other levels. The computed results are also markedly leveldependent. The crucial eects of the proper consideration of global muscles with curved paths and of spinal segments with translational degrees-of-freedom when attempting to estimate muscle forces and spinal loads in isometric lifting tasks are also demonstrated. https://scientiairanica.sharif.edu/article_2922_6d19c113404cee55b4036fce1a37c058.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 Impact of Table Size on the Performance of Thermo-Plastic Roong Systems Under Wind Uplift Pressures 2923 EN S.M. Zahrai Department of Civil Engineering,University of Tehran Journal Article 2009 05 26 Roong systems have always been vulnerable to strong wind uplift pressures. Wind forces have dynamic eects on structures, as they change in time and space. Therefore, a dynamic means of evaluating roong systems is necessary in order to identify the component of the system having the least resistance to wind uplift forces. Although researchers worldwide have conducted tests on roong structures, they have all used various table sizes, as there is still no standard chamber size for experimental purposes. This paper aims to study the impact of table size on roong system performance. To achieve this objective, extensive analytical work has been conducted to investigate the performance of roong systems subjected to wind pressure. Analytical results compared well with those obtained from experimental work, validating the numerical modeling. This paper presents some of these result comparisons. It was found that an increase in table width beyond a certain level, about 3 m for cases considered here, did not signicantly change the results, while the rate of fastener load change might be high for a smaller table width. This specic limit depends on the roong system conguration. Furthermore, a larger membrane width (fastener row spacing) would increase the width of the ideal table. Ideal table sizes were also suggested for various congurations having a TPO (Thermo-Plastic Olens) membrane and correction factors were eventually developed for dierent table sizes. https://scientiairanica.sharif.edu/article_2923_a4666cd9e1ab0e4abf05a0fb232f4ad3.pdf

Sharif University of Technology Scientia Iranica 1026-3098 15 5 2008 10 01 A Fuzzy Intelligent Information Agent Architecture for Supply Chains 2924 EN M.H. Fazel Zarandi Department of Industrial Engineering,Amirkabir University of Technology S.M. Moattar Hoseini Department of Industrial Engineering,Amirkabir University of Technology Journal Article 2009 05 26 Through the emergence of information and communication technologies and customer-oriented approaches in business and industry, for achieving competitive advantages and in order to remain at the top in every business, more exible and responsive supply chain systems are required. The next generation of supply chain systems must be agile, adaptive, cooperative, integrated and exible. Agent-based supply chain management is an approach that addresses the next generation of supply chain system features. This paper focuses on the role of an information agent in agent-based supply chain management within an uncertain environment. For this purpose, a proper modular architecture for the information agent, based on fuzzy theory, is proposed. Here, the knowledge-based module in the architecture is fuzzy rules. The system is used for updating forecasted values and implementing customer commitment in a proper manner. Finally, the proposed architecture is tested and veried and the results of the developed approach are discussed. https://scientiairanica.sharif.edu/article_2924_3953630da28e5181cffca1278517e3cf.pdf