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Tehran, Iran

Tarbiat Modares University is an exclusively graduate university with its main campus in Tehran, Iran. It was founded in 1982 and is consistently ranked among top universities in Iran. Tarbiat Modares University is the only exclusively graduate university in Iran and was founded to train university professors. Admission to the university is through national level university exams and in most programs is limited to top performers. Wikipedia.

Azadegan A.,New Mexico State University | Porobic L.,New Mexico State University | Ghazinoory S.,Tarbiat Modares University | Samouei P.,Islamic Azad University at Qazvin | Saman Kheirkhah A.,Bu - Ali Sina University
International Journal of Production Economics | Year: 2011

Manufacturing decisions inherently face uncertainties and imprecision. Fuzzy logic, and tools based on fuzzy logic, allow for the inclusion of uncertainties and imperfect information in decision making models, making them well suited for manufacturing decisions. In this study, we first review the progression in the use of fuzzy tools in tackling different manufacturing issues during the past two decades. We then apply fuzzy linear programming to a less emphasized, but important issue in manufacturing, namely that of product mix prioritization. The proposed algorithm, based on linear programming with fuzzy constraints and integer variables, provides several advantages to existing algorithm as it carries increased ease in understanding, in use, and provides flexibility in its application. © 2011 Elsevier B.V. All rights reserved. Source

Hoseinpour Gollo M.,University of Mohaghegh | Mahdavian S.M.,RMIT University | Moslemi Naeini H.,Tarbiat Modares University
Optics and Laser Technology | Year: 2011

In recent years, laser application has been introduced for bending and forming as new processes in manufacturing. The capability of laser bending demands more studies to recognize parameters influencing bending angle of sheet metals. In this study the effects of parameters such as material, laser power, beam diameter, scan velocity, sheet thickness, pass number and pulse duration on bending angle were studied by FEM initially and then followed by experiments. Furthermore, the Taguchi experimental design method was employed to pin point parameters, which significantly affect the bending process of laser bending of St12 and 304 alloy steels, which have a wide range of applications in products manufacturing. A regression analysis was conducted and a closed form equation was derived. The closed form equation can be used in industry to determine which process parameters (factors) enhance the bending angle in laser bending process. © 2010 Elsevier Ltd. All rights reserved. Source

Darbari S.,Tarbiat Modares University
Current Applied Physics | Year: 2014

In this paper, we propose the novel branched carbon nanotubes (B-CNTs) as efficient candidate for field emission applications. We believe that the double-stage structure of B-CNTs, beside formation of multiple thin branches at the apex of each vertical CNT, is responsible for the observed enhanced field emission behavior in B-CNTs. In this regard, we have derived an analytical model to evaluate the field enhancement factor (β) of the B-CNTs in comparison with CNTs, as the most popular cathode for field emission applications in the scientific society. The presented model also allows investigating the effect of different structural parameters on the field emission characteristic. We have also, compared the field emission characteristics of the B-CNTs with vertical CNTs experimentally. We observed a β value for B-CNTs which was around three times higher than CNTs. The observed enhancement in the experimental data was in good agreement with the presented analytical model. © 2014 Elsevier B.V. All rights reserved. Source

Gholami R.M.,Islamic Azad University at Tehran | Borghei S.M.,Sharif University of Technology | Mousavi S.M.,Tarbiat Modares University
Hydrometallurgy | Year: 2011

A spent processing catalyst from an Iranian oil refinery was initially characterized physically and chemically. Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were used to mobilize Al, Co, Mo and Ni from the spent catalysts under optimized conditions in batch cultures. The characteristics of the bioleach solution (pH, Eh, cell concentration and Fe(II)/Fe(III) concentration) were determined along with the concentration of metal values extracted from the catalyst. The results showed that after bioleaching using A. ferrooxidans in the presence of ferrous sulfate, maximum extractions of 63% Al, 96% Co, 84% Mo and 99% Ni were achieved after 30 days at pH 1.8-2.0. However, the highest extractions using A. thiooxidans in the presence of sulfur were 2.4% Al, 83% Co, 95% Mo and 16% Ni after 30 days at pH 3.9-4.4. The recovery of these metals decreases the environmental impact of the waste catalyst and the recycled product can be further used for industrial purposes. © 2010 Elsevier B.V. Source

Alibeigloo A.,Tarbiat Modares University | Simintan V.,Bu - Ali Sina University
Composite Structures | Year: 2011

Based on three-dimensional theory of elasticity axisymmetric static analysis of functionally graded circular and annular plates imbedded in piezoelectric layers is investigated using differential quadrature method (DQM). The plate has various edges boundary conditions and its material properties are assumed to vary in an exponential law with the Poisson ratio to be constant. This method can give an analytical solution along the graded direction using the state space method (SSM) and an effective approximate solution along the radial direction using the one-dimensional DQM. The method is validated by comparing numerical results with the results obtained in the literature. Both the direct and the inverse piezoelectric effects are investigated and the influence of piezoelectric layers on the mechanical behavior of plate is studied. The effects of the gradient index, thickness to radius ratio, and edges boundary conditions on the static behavior of FG circular and annular plates are investigated. © 2011 Elsevier Ltd. Source

Shahbazi S.,Tarbiat Modares University
Iranian Journal of Basic Medical Sciences | Year: 2016

Objective(s): Haemostasis prevents blood loss following vascular injury. It depends on the unique concert of events involving platelets and specific blood proteins, known as coagulation factors. The clotting system requires precise regulation and coordinated reactions to maintain the integrity of the vasculature. Clotting insufficiency mostly occurs due to genetically inherited coagulation factor deficiencies such as hemophilia. Materials and Methods: A relevant literature search of PubMed was performed using the keywords coagulation factors, Nonsense-mediated mRNA decay and premature translation termination codons. Search limitations included English language and human-based studies. Results: Mutations that cause premature translation termination codons probably account for one-third of genetically inherited diseases. Transcripts bearing aberrant termination codons are selectively identified and eliminated by an evolutionarily conserved posttranscriptional pathway known as nonsense-mediated mRNA decay (NMD). There are many pieces of evidence of decay among coagulation factor genes. However, the hemophilia gene (F8) does not seem to be subjected to NMD. Since the F8 gene is located on the X-chromosome, a connection between X-linked traits and mRNA decay could be assumed. Conclusion: Considering that not all genes go through decay, this review focuses on the basics of the mechanism in coagulation genes. It is interesting to determine whether this translation-coupled surveillance system represents a general rule for the genes encoding components of the same physiological cascade. © 2016, Mashhad University of Medical Sciences. All rights reserved. Source

Bigdeli F.,Payame Noor University | Morsali A.,Tarbiat Modares University
Materials Letters | Year: 2010

A new zinc(II) nitrite coordination polymer, [Zn(3-bpdh)(NO2)2]n (1), 3-bpdh = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene} was prepared and characterized by elemental analyses and IR spectroscopy. Compound 1 was structurally characterized by single-crystal X-ray diffraction and is one-dimensional polymer with coordination environment of distorted octahedral, ZnN2O4. Thermal decomposition of this precursor in oleic acid at 240 °C under air atmosphere results in the formation of nanoparticles of ZnO. The nano-materials were characterized by scanning electron microscopy, X-ray powder diffraction (XRD) and IR spectroscopy. The thermal stability of nano-structure ZnO was studied by thermal gravimetric and differential thermal analyses and showed that there is no reportable loss of weight in the TGA curves that proves the existence of zinc(II) oxide. This study demonstrates the coordination polymers may be suitable precursors for the preparation of nanoscale materials. © 2009 Elsevier B.V. All rights reserved. Source

Haghifam M.R.,Tarbiat Modares University | Manbachi M.,Islamic Azad University at Tehran
International Journal of Electrical Power and Energy Systems | Year: 2011

Many subsystems are involved in the reliability modeling of combined heat and power (CHP) systems, but in most studies these subsystems have not been classified and in many cases have been considered separately. Furthermore, calculating the reliability from the generation point to the consumer has not yet been studied. Herein, we classify combined heat and power subsystems and model their reliability, availability and mean-time-to-failure indices based on interactions between subsystems from the generation site to consumer delivery. The proposed CHP reliability and availability model is based on the state space and the continuous Markov method with electricity-generation, fuel-distribution and heat-generation subsystems. The effects of fuel- and water-distribution networks at the CHP site and the hot-water-distribution network on the consumer-utility reliability of CHP systems were fully assessed in an applicable case study. Additionally, we present a sensitivity analysis for island, standby and parallel operational modes of CHP systems. The results from the case study prove that improving the gas-distribution network, the network delivering hot water to the consumers and the water-delivery network to the CHP, in addition to optimizing the failure and repair rates of CHP systems, have considerable effects on the reliability improvement of the complete integrated system and have major roles in technical and economic feasibility studies of CHP systems. © 2010 Elsevier Ltd. All rights reserved. Source

Fakhimi A.,New Mexico Institute of Mining and Technology | Fakhimi A.,Tarbiat Modares University | Tarokh A.,New Mexico Institute of Mining and Technology
International Journal of Rock Mechanics and Mining Sciences | Year: 2013

Fracture of rock involves formation of a localized region of damage or cohesive process zone, which controls size effects on strength and stability. Therefore, any attempt in predicting size of process zone is of prime importance in fracture study of quasi-brittle materials. In this paper, an approximate theoretical relationship between size of process zone and specimen size is proposed. The appropriateness of this relationship is examined by conducting a discrete element analysis of rock fracture. A softening contact bond model is used to study the process zone around a notch tip in three point bending tests. The numerical analysis is utilized to obtain the nominal tensile strength, apparent fracture toughness, and width of process zone. It is shown that the apparent fracture toughness is a function of the specimen size, and that the change in nominal tensile strength with specimen size can be captured by Bazant's size effect law. In addition, both the theoretical arguments and the numerical results suggest that the inverse of width of the crack tip process zone has a linear relationship with the inverse of specimen size. The numerical results indicate a stronger relationship between width of process zone and specimen size for a material with a larger value of characteristic size. On the other hand, for a brittle material, specimen size has a small or no impact on the size of the process zone. © 2013 Elsevier Ltd. Source

Nourani V.,University of Tabriz | Babakhani A.,Tarbiat Modares University
Journal of Computing in Civil Engineering | Year: 2013

In this study, the radial basis function (RBF) spatial interpolation method was used to estimate the potential water heads through an earthen dam. The multiquadric (MQ) function was used to discretize the seepage governing partial differential equation and related boundary conditions. The function contains a shape coefficient of c, which plays an important role in model calibration. Therefore, the coefficient of c was first optimized via Hardy and cross validation methods, and then, by employing the optimal c (copt), two scenarios of modeling with and without considering the internal conditions were provided and the results were compared with the results of the finite difference method (FDM). In the next step, an artificial neural network was used for handling the nonlinear time variability of the phenomenon to cope with the limitations of the FDM and RBF methods in temporal modeling. Thus, by training neural networks for the piezometers located in the core, the potential time series of water were predicted and their results were imposed upon the RBF method as the internal conditions, along with the boundary conditions for spatial-temporal modeling of the water heads. Finally, the assumed time-invariant inherency of c was confirmed by the cross-validation method. The results show no notable time variation in time series of copt, and therefore, it can be concluded that the value of the shape coefficient in MQ formulations generally depends on the geometry of the problem rather than the temporal variation of the boundary conditions. © 2013 American Society of Civil Engineers. Source

Saghaei H.,Islamic Azad University at Tehran | Ebnali-Heidari M.,Shahrekord University | Moravvej-Farshi M.K.,Tarbiat Modares University
Applied Optics | Year: 2015

Using numerical analysis, we compare the results of optofluidic and rod filling techniques for the broadening of supercontinuum spectra generated by As2Se3 chalcogenide photonic crystal fibers (PCFs). The numerical results show that when air-holes constituting the innermost ring in a PCF made of As2Se3-based chalcogenide glass are filled with rods of As2S3-based chalcogenide glass, over a wide range of mid-IR wavelengths, an ultra-flattened near-zero dispersion can be obtained, while the total loss is negligible and the PCF nonlinearity is very high. The simulations also show that when a 50 fs input optical pulse of 10 kW peak power and center wavelength of 4.6 μm is launched into a 50mm long rod-filled chalcogenide PCF, a ripple-free spectral broadening as wide as 3.86 μm can be obtained. © 2015 Optical Society of America. Source

Gholami A.,University of Tehran | Hosseini S.M.,Tarbiat Modares University
IEEE Transactions on Signal Processing | Year: 2011

Estimating a reliable and stable solution to many problems in signal processing and imaging is based on sparse regularizations, where the true solution is known to have a sparse representation in a given basis. Using different approaches, a large variety of regularization terms have been proposed in literature. While it seems that all of them have so much in common, a general potential function which fits most of them is still missing. In this paper, in order to propose an efficient reconstruction method based on a variational approach and involving a general regularization term (including most of the known potential functions, convex and nonconvex), we deal with i) the definition of such a general potential function, ii) the properties of the associated "proximity operator" (such as the existence of a discontinuity), and iii) the design of an approximate solution of the general "proximity operator" in a simple closed form. We also demonstrate that a special case of the resulting "proximity operator" is a set of shrinkage functions which continuously interpolate between the soft-thresholding and hard-thresholding. Computational experiments show that the proposed general regularization term performs better than ℓp -penalties for sparse approximation problems. Some numerical experiments are included to illustrate the effectiveness of the presented new potential function. © 2011 IEEE. Source

Saffarzadeh A.,Payame Noor University | Saffarzadeh A.,Institute for Research in Fundamental Sciences | Farghadan R.,Tarbiat Modares University
Applied Physics Letters | Year: 2011

The coherent spin-polarized electron transport through a zigzag-edge graphene flake (ZGF), sandwiched between two semi-infinite armchair graphene nanoribbons, is investigated by means of Landauer-Buttiker formalism. To study the edge magnetism of the ZGF, we use the half-filled Hubbard model within the Hartree-Fock approximation. The results show that the junction acts as a spin filter with high degree of spin polarization in the absence of magnetic electrodes and external fields. By applying a gate voltage the spin-filtering efficiency of this device can be effectively controlled and the spin polarization can reach values as high as 90%. © 2011 American Institute of Physics. Source

Mafi Gholami R.,Islamic Azad University at Ahvaz | Mousavi S.M.,Tarbiat Modares University | Borghei S.M.,Sharif University of Technology
Journal of Industrial and Engineering Chemistry | Year: 2012

The present study examines the biorecovery of heavy metals from a spent refinery catalyst obtained from one of the oil refineries in Iran using Aspergillus niger. Bioleaching experiments were carried out in batch cultures using A. niger in the one-step process to mobilize Co, Mo and Ni from hazardous spent catalysts. Response surface methodology (RSM) was applied for the design and analysis of experiments with the optimization of pH, temperature, inoculum percentage, pulp density and rotation speed during the bioleaching of the metals. Experiments were designed as per the central composite design (CCD) technique. Three cubic mathematical models were derived for prediction of the responses. In process optimization, maximal values of Co, Mo and Ni recoveries were achieved as 71%, 69% and 46%, respectively, with a pH of 5.0, a temperature of 31°C, a pulp density of 2. g/L, a rotation speed of 115. rpm, and using a 12% inoculum. © 2011 The Korean Society of Industrial and Engineering Chemistry. Source

Husseinzadeh Kashan A.,Tarbiat Modares University
Applied Soft Computing Journal | Year: 2014

League Championship Algorithm (LCA) is a recently proposed stochastic population based algorithm for continuous global optimization which tries to mimic a championship environment wherein artificial teams play in an artificial league for several weeks (iterations). Given the league schedule in each week, a number of individuals as sport teams play in pairs and their game outcome is determined in terms of win or loss (or tie), given the playing strength (fitness value) along with the intended team formation/arrangement (solution) developed by each team. Modeling an artificial match analysis, each team devises the required changes in its formation (generation of a new solution) for the next week contest and the championship goes on for a number of seasons (stopping condition). An add-on module based on modeling the end season transfer of players is also developed to possibly speed up the global convergence of the algorithm. Extensive analysis to verify the rationale of the algorithm and suitability of the updating equations together with investigating the effect of different settings for the control parameters are carried out empirically on a large number of benchmark functions. Results indicate that LCA exhibits promising performance suggesting that its further developments and practical applications would be worth investigating in the future studies. © 2013 Elsevier B.V. Source

Rostamnia S.,Islamic Azad University at Maragheh | Rostamnia S.,Tarbiat Modares University
Research Journal of Chemistry and Environment | Year: 2011

Nanoparticles based on toxic properties of quantum dot (Q.D.) have some limitation in environment and green applications. In view of the great attention paid to the development of eco-friendly and green chemistry approaches and based on recent advances in green support media, eco-friendly supported nanoparticles are used as catalyst that have led to a rational approach to the design of new heterogeneous green catalysts. Amongst the advantages of supported nanoparticles, the most significant is their large size (no Q.D.) and hence they can accommodate a greater number of eco-friendly surfaces such as clays, zeolites etc. for better catalytic activity and green media under controlled conditions. Source

Ghoddousi P.,Iran University of Science and Technology | Eshtehardian E.,Tarbiat Modares University | Jooybanpour S.,Amirkabir University of Technology | Javanmardi A.,Iran University of Science and Technology
Automation in Construction | Year: 2013

Minimizing both project time and cost is an important matter in today's competitive environment. Therefore trade-off between project time and cost is necessary. In projects, each activity can be started at different time points, depending on its precedence relationship and resource availability. Also cost and duration of the activities could be changed depending on the allocated resources. In addition, another strategy that affects the project total time and cost is resource leveling, which is applied to reduce excessive fluctuations in the resource usage. In this paper multi-mode resource-constrained project scheduling problem (MRCPSP), discrete time-cost trade-off problem (DTCTP) and also resource allocation and resource leveling problem (RLP) are considered simultaneously. This paper presents the multi-mode resource-constrained discrete time-cost-resource optimization (MRC-DTCRO) model in order to select starting the time and the execution mode of each activity satisfying all the project constraints. To solve these problems, non-domination based genetic algorithm (NSGA-II) is employed to search for the non-dominated solutions considering total project time, cost, and resources moment deviation as three objectives. The results of MRC-DTCRO model presented in this paper show that adding the resource leveling capability to the previously developed multi-mode resource-constrained discrete time-cost trade-off problem (MRC-DTCTP) models provides more practical solutions in terms of resource allocation and leveling, which makes this research applicable to both construction industry and researchers. © 2012 Elsevier B.V. All rights reserved. Source

Alizadeh N.,Tarbiat Modares University | Saburi N.,Islamic Azad University | Hosseini S.E.,Islamic Azad University
Food Control | Year: 2012

Benzoate-doped polypyrrole (PPy-Bz) was prepared electrochemically by anodic polymerization of pyrrole in the presence of benzoate ion (Bz) in an aqueous solution and was used as a solid-state PPy-Bz ion selective sensor. The effect of polymerization conditions on the characteristics of the potential response of the sensors was also discussed. The solid-state PPy-Bz sensor, showed a near-Nernstian behavior over 9 × 10 -5-2 × 10 -2 mol L -1 Bz - with a detection limit of 5 × 10 -5 mol L -1 in an aqueous solution. The potential response of the sensor was reproducible in the range pH 2-9 and was not affected by pH between 6 and 8. Selectivity of the sensor over diverse preservative reagents (sorbate, acetate and citrate) and inorganic salts was evaluated. The PPy-Bz sensor was applied for determination of Bz - ions in carbonated soft drinks by using potentiometry and the results are similar with values obtained by high-performance chromatography. © 2012 Elsevier Ltd. Source

Azizi-Shotorkhoft A.,University of Agriculture and Natural Resources Ramin | Rezaei J.,Tarbiat Modares University | Fazaeli H.,Animal Science Research Institute
Animal Feed Science and Technology | Year: 2013

A 28-d experiment was performed to evaluate the influence of replacing dietary corn/barley with molasses at levels of 0 (M0), 50 (M50) and 100 (M100) g/kg dietary dry matter (DM), as energy sources, in the diets containing heat-processed broiler litter (HBL) (240. g/kg DM) in male Moghani sheep. Digestibility, microbial protein supply (MPS), ruminal parameters and blood metabolites were measured. The digestibility of DM and crude protein (CP) in experimental sheep linearly increased (L, P=0.01) as level of molasses enhanced in the diets. Addition of molasses to diet linearly increased MPS (L, P=0.01) compared to sheep fed the control diet. Ruminal pH and ammonia concentrations linearly declined (L, P<0.05) as level of molasses increased in the diet. There was no difference (P>0.05) in ruminal volatile fatty acid concentrations, except a linear increase in the molar proportion of butyrate (L, P=0.02) among the molasses supplemented groups. Blood urea-N linearly decreased (L, P=0.02) in sheep fed molasses compared to the control group. It can be concluded that replacing corn/barley with molasses in sheep diet improved the utilization of the diet containing HBL. © 2012 Elsevier B.V. Source

Abbaspur R.,Tarbiat Modares University
Nuclear Physics B | Year: 2011

In this paper we examine a deformation of the 1/2 BPS kink solitons of a WZ model with a cubic superpotential in two Euclidean dimensions caused by introducing non(anti)commutativity in the superspace formulation of the theory. The spacetime Lagrangian of the deformed model consists of the ordinary WZ terms plus corrections in the form of a kinetic and a cubic term for the auxiliary field, both in proportion to the determinant of the non(anti)commutativity parameters Cαβ. We compute the correction to the "orbit" equation, relating the auxiliary and the scalar fields together, and subsequently derive the modifications to the BPS equation and to its solution up to first order in λ≡det(Cαβ). We give a description of the deformed solitons in terms of the 1/2 BPS states of an effective N=1 supersymmetric non-linear σ-model in two dimensions, using which we derive the first-order correction to the BPS mass formula for these solitons. © 2010 Elsevier B.V. Source

Hosseinifar M.,Islamic Azad University at Tehran | Ahmadi V.,Tarbiat Modares University | Abaeiani G.,Laser and Optics Research School
Journal of Lightwave Technology | Year: 2011

A novel structure of unitraveling carrier photodiodes (UTC-PDs) with high-speed, high-efficiency, and wavelength selective characteristics is presented. Including the essential features of resonant cavity enhanced photodiodes and waveguide photodiodes, we propose microring-based UTC-PDs (MR-UTC-PDs) which can achieve excellent high-speed and high-quantum efficiency characteristics simultaneously. The photoresponse of MR-UTC-PDs is based on a drift-diffusion model. Photoresponse characteristics of MR-UTC-PDs, which depend on device parameters and coupling conditions, are investigated and it is shown that the overcoupled structures are suitable for high-speed photodetection. The important features of the device, such as efficiency enhancement and wavelength selectivity are discussed and the trade-off between 3 dB bandwidth and efficiency is solved for nanoscaled absorption layer. Additionally, the bandwidth-efficiency product in the order of several hundreds gigahertz can be obtained even with low photoabsorption layers. © 2006 IEEE. Source

Naghdi M.,Tarbiat Modares University
International Journal of Modern Physics A | Year: 2011

Making use of ansatzs for the form fields in the ten-dimensional type IIA supergravity version of the ABJM model, we come with a solution in the Euclidean signature recognized as a monopole instanton-like object. Indeed we will see that we can have a (anti-)self-dual solution at a special limit. While as a topological object, its backreaction on the original background should be ignorable, we show the energymomentum tensors vanish exactly. On the field theory side, the best counterpart is an U(1) gauge field of a gauge transformation. To adjust with bulk, the gauge field must prompt to a dynamic one without adding any kinetic term for this dual photon except a marginal, Abelian AB-type Chern-Simons term on the boundary. We will see how both side solutions match next to another confirmation from some earlier works of this vortexparticle duality. © 2011 World Scientific Publishing Company. Source

Marandi F.,Payame Noor University | Morsali A.,Tarbiat Modares University
Inorganica Chimica Acta | Year: 2011

A new nano-sized lead(II) one-dimensional coordination polymer with Pb⋯F interactions, [Pb(μ-TFPB) 2] n (1) [TFPB - = 4,4,4-trifluoro-1-phenyl-1,3-butandionate], has been synthesized and characterized by SEM, X-ray powder diffraction, IR spectroscopy and elemental analyses. The single-crystal X-ray data of compound 1 show that the Pb(II) atoms have a hemidirected coordination sphere with an environment of PbO 6F 2. The presence of a stereo-chemically active lone pair of the lead atom is apparently the reason that the neighboring bridging bond relative to gap of coordination sphere are so long. Therefore arrangement of "TFPB -" ligands suggests a gap or hole in coordination geometry around the lead(II) ions. PbO nanoparticles were obtained by calcination of the nano-sized compound 1 at 600 °C. © 2011 Elsevier Ltd. All rights reserved. Source

Hosseini S.A.,Islamic Azad University at Tehran | Ghassemian H.,Tarbiat Modares University
International Journal of Remote Sensing | Year: 2011

The support vector machine (SVM) has been a dominant machine-learning technique in the last decade and has demonstrated its efficiency in many applications. Research on classification of hyperspectral images have shown the efficiency of this method to overcome the Hughes phenomenon for classification of such images. A major drawback of classification by SVM is that this classifier was originally developed to solve binary problems, and the algorithms for multiclass problems usually have a high-computational load. In this article, a new and fast method for multiclass problems is proposed. This method has two stages. In the first stage, samples are classified by a maximum likelihood (ML) classifier, and in the second stage, SVM selects the final label of a sample among high-probability classes for that sample by a tree structure. So, for each sample, only some classes must be searched by SVM to find its label. The uncertainty of ML classification for a sample is obtained by the entropy of probabilities, and the number of classes that must be searched by SVM for a sample is obtained based on the uncertainty of that sample in the primary ML classification. This approach is compared with two widely used multiclass algorithms: one-against-one (OAO) and directed acyclic graph (DAGSVM). The obtained results on real data from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) revealed less computational time and better accuracy compared to these multiclass algorithms. © 2011 Taylor & Francis. Source

This study focuses on the feasibility of applying alternative futures and scenario analysis in landscape planning during climate change to provide a wider perspective and deeper understanding of this approach for better use and more effective application in the future. The study consists of a literature review and an analysis of recent applied projects carried out worldwide. In addition, an electronic survey was conducted from March to September 2014 to examine viewpoints on the use and application of this approach with reference to climate-change impacts. The survey participants were a group of highly experienced researchers from eighteen countries involved in at least one applied project since 2000 relating to this topic. After analysis of more than forty applied projects, the survey results were incorporated into the analysis to create a comprehensive picture regarding the potentials and limitations of alternative futures and scenario analysis in landscape planning with particular attention to climate change. The findings show that this method is one of the most effective decision-making approaches for adopting landscape policies where landscapes change rapidly under the pressure of urbanisation and climate change. Nevertheless, there is a gap between the advances offered by the approach in various dimensions and the complexity of patterns, uncertainties and upheavals in landscapes due to climate-change impacts in the urbanising world. The research indicates that the approach opens up a great opportunity for decision-makers to expand their perspective and adopt appropriate landscape policies before reaching a point of no return from the sustainability point of view. Meanwhile, there are challenges and barriers in the application of alternative futures and scenario analysis for envisioning the landscapes influenced by climate change and urbanisation that should be pushed back. Although informative, this research raises new questions about this approach and its applications in the future, providing a basis for further research. Source

Eslahchi M.R.,Tarbiat Modares University | Dehghan M.,Amirkabir University of Technology
Computers and Mathematics with Applications | Year: 2011

In this research first we explicitly obtain the relation between the coefficients of the Taylor series and Jacobi polynomial expansions. Then we present a new method for computing classical operational matrices (derivative, integral and product) for general Jacobi orthogonal functions (polynomial and rational). This method can be used for many classes of orthogonal functions. © 2011 Elsevier Ltd. All rights reserved. Source

In this paper free vibration behavior of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) cylindrical panel embedded in piezoelectric layers with simply supported boundary conditions is investigated by using three-dimensional theory of elasticity. By using Fourier series expansion along the longitudinal and latitudinal directions and state space technique across the thickness direction, state space differential equations are solved analytically. The traction-free surface conditions then give rise to the characteristic equation for natural frequencies. Accuracy and convergence of the present approach are validated by comparing the numerical results with those found in literature. In addition, the effects of volume fraction of CNT, four cases of FG-CNTRC, piezoelectric layer thickness, mid radius to thickness ration and modes number on the vibration behavior of the hybrid cylindrical panel are also examined.© 2013 Elsevier Masson SAS. All rights reserved. Source

Zavvari M.,Islamic Azad University at Urmia | Ahmadi V.,Tarbiat Modares University
Infrared Physics and Technology | Year: 2014

In this paper a single photon detector with operating wavelength of 6 μm is proposed and its performance characteristics are studied. Intersubband absorption of single photons in quantum dot layers leads to creation of photoelectrons which are injected to multiplication region and under above breakdown condition a large output pulse is generated. The detector is designed for self quenching operation in which an additional layer called transient carrier buffer (TCB) is used for trapping of backward avalanche generated holes at the interface of TCB and charge layer. The accumulated holes impose an additional charge in such a way that the voltage across the multiplication region drops and the output is quenched. A model is developed to analyze the performance of detector and results of simulation predict detection efficiency about 12% at T = 150 K. Also the quenching and recovering performance of detector is studied and results show that both higher temperatures and higher bias improve dynamics of detector. However higher temperatures result in higher dark count rate. © 2013 Elsevier B.V. All rights reserved. Source

Jenabali Jahromi S.A.,Islamic Azad University at Marvdasht | Khajeh A.,Shiraz University | Mahmoudi B.,Tarbiat Modares University
Materials and Design | Year: 2012

AISI 410 martensitic stainless steel (MSS) samples were conventionally heat treated in diverse quenching environments to obtain three different microstructures: fine ferrite, fine and coarse martensite. Furthermore, laser surface treatment (LST) was done by pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser to compare the effect of short-term diffusion on the hardness of the different microstructures. The microstructure and microhardness of the samples were investigated by means of an optical microscope and Vickers microhardness tester respectively. Moreover, finite element simulation was done using ABAQUS finite element software to predict cooling curves and temperature histories at different depths of workpiece and to calculate the depth of fully hardened and partially hardened material. A comparison between theoretical and experimental results showed a good conformity and that LST is an effective approach to improve the hardness of the ferrite, despite the coarse and fine martensite phases. © 2011 Elsevier Ltd. Source

Alibeigloo A.,Tarbiat Modares University | Kani A.M.,Babol Noshirvani University of Technology | Pashaei M.H.,Babol Noshirvani University of Technology
International Journal of Pressure Vessels and Piping | Year: 2012

Based on the three-dimensional theory of elasticity, free vibration analysis of a functionally graded cylindrical shell embedded in piezoelectric layers is performed by using an analytical method for simply supported boundary conditions and a semi-analytical method for non-simply supported conditions. Material properties are assumed to vary along the thickness according to an exponential law with Poisson's ratio held constant. For non-simply supported conditions, this method can give an analytical solution along the graded direction using the state space method (SSM) and an effective approximate solution along the axial direction using the one dimensional differential quadrature method (DQM). Numerical results are compared to those available in the literature to validate the convergence and accuracy of the present approach. The effects of material property gradient index, edge conditions, mid-radius to thickness ratio, length to mid-radius ratio and the piezoelectric thickness on vibration behavior of shell are investigated. © 2011 Elsevier Ltd. Source

Yasavol N.,Tarbiat Modares University | Mahboubi F.,Amirkabir University of Technology
Materials and Design | Year: 2012

Plasma nitriding is a surface treatment process, which is widely used to improve wear, fatigue and corrosion resistance of the industrial parts. Nevertheless, corrosion resistance can be enhanced by oxidizing of the nitrided components. This paper considers the duplex treatment of plasma nitriding and post-oxidizing of AISI 4130 low alloy steel. After plasma nitriding, the post-oxidizing treatment was done in the various gas mixtures of O2/H2 and temperatures. The treated samples were characterized using metallographic techniques, XRD, SEM, micro-hardness and potentiodynamic test. The X-ray diffraction confirmed the development of gamma prime and epsilon iron nitride phases during the nitriding, and hematite (Fe2O3) and magnetite (Fe3O4) phases under the oxidizing process. The sample oxidized under O2/H2 volume ratio of 1/3 showed the best corrosion resistance, which is attributed to the formation of an almost single phase magnetite oxide layer on the top of the compound layer. © 2012. Source

Niknejad A.,Yasouj University | Elahi S.A.,Yasouj University | Liaghat G.H.,Tarbiat Modares University
Materials and Design | Year: 2012

This paper investigates the effect of polyurethane foam-filler on the lateral plastic deformation in the circular tubes under radial quasi-static loading, experimentally. For this purpose, the specimens were prepared with five different diameters and thicknesses. For each constant diameter of specimens, several tubes with different lengths were prepared. All geometrical groups of specimens in the lateral compression tests (flattening) were used in empty and polyurethane foam-filled conditions. The effect of length, diameter and wall thickness of tubes on the lateral load, energy absorption and the specific absorbed energy were studied. The experimental results show that the polyurethane foam-filler increase the energy absorption capability of tubes and furthermore the increment of the energy absorption in thinner tubes is more than thicker specimens. Results show that using the polyurethane foam in the circular tubes under the lateral compression works as an excellent filler. © 2011 Elsevier Ltd. Source

Ghassemian H.,Tarbiat Modares University
Information Fusion | Year: 2016

The recent years have been marked by continuous improvements of remote sensors with applications like monitoring and management of the environment, precision agriculture, security and defense. On the one hand, the high spectral resolution is necessary for an accurate class discrimination of land covers. On the other hand, the high spatial resolution is required for an accurate description of the texture and shapes. Practically, each kind of imaging sensor can only focus on a given different operating range and environmental conditions, the reception of all the necessary information for detecting an object or classifying a scene is not possible. So, for the full exploitation of multisource data, advanced analytical or numerical image fusion techniques have been developed. In this paper, we review some popular and state-of-the-art fusion methods in different levels especially at pixel level. In addition to reviewing of different fusion methods, varied approaches and metrics for assessment of fused product are also presented. © 2016. Source

Namvar-Mahboub M.,Ferdowsi University of Mashhad | Pakizeh M.,Ferdowsi University of Mashhad | Davari S.,Tarbiat Modares University
Journal of Membrane Science | Year: 2014

Thin-film nanocomposite (TFN) membrane containing amino-functionalized UZM-5 nanoparticles was synthesized by interfacial polymerization on polyetherimide (PEI)/modified SiO2 asymmetric substrate tailored for organic solvent nanofiltration OSN process. m-Phenylenediamine (MPD) with trimesoyl chloride (TMC) was polymerized to prepare polyamide layer. UZM-5 nanoparticles (~73nm) were synthesized and then functionalized by aminopropylediethoxymethylsilane (APDEMS) and finally incorporated into polyamide (PA) selective layer at concentrations ranging from 0 to 0.2w/v%. The as-prepared TFN membranes were characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and contact angle measurements. The performances of membranes were also evaluated through dewaxing solvents (MEK and toluene) recovery from lube oil. FESEM and SEM images clearly confirmed that the polyamide/UZM-5 nanocomposite top layer was formed on the support surface and its morphology was significantly affected by UZM-5 loading. Interaction between functional groups of modified UZM-5 nanoparticles and polyamide matrix was established by ATR-FTIR. AFM results revealed that in the range of 0-0.1w/v% zeolite loading, the surface roughness of TFN membranes decreased due to the change of polyamide structure while at 0.2w/v% of zeolite loading, an increase in surface roughness was observed. It also resulted in enhanced hydrophilicity of TFN membranes in the range of 0-0.1w/v% UZM-5 loading, proved by a decreased water contact angle. The permeation test results indicated that the existence of UZM-5 in the polyamide selective layer improved both oil rejection and permeate flux under optimal concentration (0.02% w/v of UZM-5). © 2014 Elsevier B.V. Source

Bahrami A.,Shiraz University | Besharati-Seidani A.,Tarbiat Modares University | Abbaspour A.,Shiraz University | Shamsipur M.,Razi University
Electrochimica Acta | Year: 2014

This work reports the preparation of a voltammetric sensor for selective recognition and sensitive determination of lead ions using a carbon paste electrode (CPE) impregnated with novel Pb2+-ion imprinted polymeric nanobeads (IIP) based on dithizone, as a suitable ligand for complex formation with Pb2+ ions. The differential pulse anodic stripping voltammetric technique was employed to investigate the performance of the prepared IIP-CPE for determination of hazardous lead ions. The designed modified electrode was revealed linear responses in the ranges of 3.0 × 10-10 - 1.0 × 10-9 mol dm-3 and 1.0 × 10-8 - 1.0 × 10-6 mol dm-3 with a limit of detection (LOD) of 1.0 × 10-10 mol dm-3 (S/N =3). It was found that the peak currents of the modified electrode for Pb2+ ions were at maximum value in acetate buffer of pH 4.0. The optimized preconcentration potential and accumulation time were to be -1.0 V and 25 s, respectively. The applicability of the proposed sensor to lead determination in tap water and lipstick samples are reported. © 2013 Elsevier Ltd. Source

Size-controlled crystalline basic nanoporous coordination polymers of IRMOF-3 (Zn4O(H2N-TA)3) and its catalytically study for synthesis of tetrahydro-chromenes was investigated. IRMOF-3 was found to be an efficient, selective and waste-free green solid base for the coupling reaction of dimedone, aldehydes, and malononitrile. The catalyst can be isolated from the reaction mixture and reused at least 5 times. © 2013 Elsevier B.V. All rights reserved. Source

Salarizadeh P.,Amirkabir University of Technology | Javanbakht M.,Amirkabir University of Technology | Abdollahi M.,Tarbiat Modares University | Naji L.,Amirkabir University of Technology
International Journal of Hydrogen Energy | Year: 2013

Nanocomposite membranes based on the poly(vinyl alcohol) (PVA)/poly(sulfonic acid)-grafted silica nanoparticles (PSA-g-SN) were prepared via solvent casting of PVA cross linked by glutardialdehyde in the presence of various amounts (0-20 wt%) of silica nanoparticles (SN), poly(styrene sulfonic acid)- (PSSA-g-SN) and poly (2-acrylamido-2-methyl-1-propane sulfonic acid)-grafted silica nanoparticles (PAMPS-g-SN) as hydrophilic inorganic modifiers. PSA-g-SN nanoparticles were synthesized by surface-initiated redox grafting of SSA and AMPS monomers from the surface of the aminopropylated silica nanoparticles. Membranes were then characterized by FTIR, impedance spectroscopy, thermogravimetric analysis (TGA), water uptake, tensile strength test and SEM. The best proton conductivity was observed for membranes containing 5 wt% of nanoparticles. Among three nanoparticles used, the highest proton conductivity (10.4 mS/cm) was observed for PVA membrane prepared in the presence of 5 wt% PAMPS-g-SN nanoparticles. Results showed that grafting of sulfonated monomer onto the silica nanoparticles enhances various properties, for example proton conductivity, of the polymer electrolyte membranes (PEMs). Crown Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source

Bahramian A.R.,Tarbiat Modares University
Iranian Polymer Journal (English Edition) | Year: 2013

Ablation is an effective and reliable method largely used in aerospace structures and other high temperature conditions to protect the payload from the damaging effects of external high heat flux. In an ablation process, the high heat fluxes are dissipated by the material through a series of endothermic processes. This finally leads to the loss and the consumption of the material itself. The ablative material keeps the surface temperature within a certain range, and as a consequence an increase of the heat flux will not cause a consistent temperature rise, but will bring about an increase of the surface recession rate. The objective of this work is to give information on the effect of the external heat flux to evaluate effective thermal diffusivity behavior and ablation performance of carbon fiber reinforced composite based on novolac resin. Here, we calculate the effective thermal diffusivity of this composite at different heat flux conditions using inverse solution technique of conservation equations of mass and energy. The ablation performance evaluation is based on experimental transient ablation rate measurement in oxyacetylene flame test. The results of this work explained the ablation process and thermal diffusivity behavior of this composite as a high performance heat shield at high external heat fluxes. © 2013 Iran Polymer and Petrochemical Institute. Source

Badiei A.,University of Tehran | Goldooz H.,Tarbiat Modares University | Ziarani G.M.,Alzahra University
Applied Surface Science | Year: 2011

8-Hydroxyquinoline (8-HQ) was attached to mesoporous silica by sulfonamide bond formation between 8-hydroxyquinoline-5-sulfonyl chloride (8-HQ-SO 2Cl) and aminopropyl functionalized SBA-15 (designated as SBA-SPS-Q) and then aluminum complexes of 8-HQ was covalently bonded to SBA-SPS-Q using coordinating ability of grafted 8-HQ.The prepared materials were characterized by powder X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FT-IR), thermal analysis (TGA-DTA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental analysis and fluorescence spectra. The environmental effects on the emission spectra of grafted 8-HQ and its complexes were studied and discussed in details. © 2010 Elsevier B.V. All rights reserved. Source

Although radiation carcinogenesis has been shown both experimentally and epidemiologically, the use of ionizing radiation is also one of the major modalities in cancer treatment. Various known cellular and molecular events are involved in carcinogenesis. Apart from the known phenomena, there could be implications for carcinogenesis and cancer prevention due to other biological processes such as the bystander effect, the abscopal effect, intrinsic radiosensitivity and radioadaptation. Bystander effects have consequences for mutation initiated cancer paradigms of radiation carcinogenesis, which provide the mechanistic justification for low-dose risk estimates. The abscopal effect is potentially important for tumor control and is mediated through cytokines and/or the immune system (mainly cell-mediated immunity). It results from loss of growth and stimulatory and/or immunosuppressive factors from the tumor. Intrinsic radiosensitivity is a feature of some cancer prone chromosomal breakage syndromes such as ataxia telangectiasia. Radiosensitivity is manifested as higher chromosomal aberrations and DNA repair impairment is now known as a good biomarker for breast cancer screening and prediction of prognosis. However, it is not yet known whether this effect is good or bad for those receiving radiation or radiomimetic agents for treatment. Radiation hormesis is another major concern for carcinogenesis. This process which protects cells from higher doses of radiation or radio mimic chemicals, may lead to the escape of cells from mitotic death or apoptosis and put cells with a lower amount of damage into the process of cancer induction. Therefore, any of these biological phenomena could have impact on another process giving rise to genome instability of cells which are not in the field of radiation but still receiving a lower amount of radiation. For prevention of radiation induced carcinogenesis or risk assessment as well as for successful radiation therapy, all these phenomena should be taken into account. © 2012 by the authors; licensee MDPI, Basel, Switzerland. Source

Alibeigloo A.,Tarbiat Modares University | Liew K.M.,City University of Hong Kong
Composite Structures | Year: 2014

This paper presents an exact three-dimensional free vibration solution for sandwich cylindrical panels with functionally graded core. Material properties of the FGM core are assumed to be graded in the radial direction, according to a simple power-law distribution in terms of volume fractions of the constituents. Poisson's ratio is assumed to be constant. The governing equation of motions is formulated based on the 3D-theory of elasticity and displacement fields are expanded in Fourier series along the in-plane coordinates which satisfy the simply supported edges boundary conditions. The state space technique is used to obtain natural frequencies analytically. Accuracy and convergence of the present approach are examined by comparing the analytical results with the existing values in literature. The parametric study is carried out to discuss the effects of gradient index, geometrical properties such as span angle, facing layers thickness and axial length to mid radius ratio on the frequency behavior of the sandwich panel. The obtained exact solution shows that the FGM core has significant effects on the vibration behavior of sandwich cylindrical panel. This fist known exact solution serves as a benchmark for assessing the validity of numerical methods or two-dimensional theories used to analyses of sandwich cylindrical panels. © 2014. Source

Based on theory of elasticity, static behavior of functionally graded carbon nanotube reinforced composite (FG-CNTRC) rectangular host plate attached to thin piezoelectric layers subjected to thermal load and or electric field is studied. It is assumed that temperature gradient does not affect the thermo-elastic constants of the plate. Distribution of CNT is uniformly or functionally graded along the plate thickness. Analytical solutions for the temperature, stress and displacement fields for the FG-CNTRC plate with simply-supported edges are derived by using the Fourier series expansion along in-plane coordinates and state-space technique across thickness direction. The present procedure is validated by comparing the numerical results with the available published results. Parametric studies are performed to assess the effects of CNT volume fraction, case of CNT distribution along the thickness direction, surface boundary conditions, applied voltage, aspect ratio and length to thickness ratio on the behavior of FG-CNTRC rectangular plate. © 2014 Elsevier Ltd. Source

Amiri F.,Sharif University of Technology | Yaghmaei S.,Sharif University of Technology | Mousavi S.M.,Tarbiat Modares University | Mousavi S.M.,Lappeenranta University of Technology
Bioresource Technology | Year: 2011

Adaptation of Penicillium simplicissimum with different heavy metals present in a spent hydrocracking catalyst, as well as one-step, two-step, and spent medium bioleaching of the spent catalyst by the adapted fungus, was examined in batch cultures. Adaptation experiments with the single metal ions Ni, Mo, Fe, and W showed that the fungus could tolerate up to 1500. mg/L Ni, 8000. mg/L Mo, 3000. mg/L Fe, and 8000. mg/L W. In the presence of multi-metals, the fungus was able to tolerate up to 300. mg/L Ni, 200. mg/L Mo, 150. mg/L Fe and 2500. mg/L W. A total of 3% (w/v) spent catalyst generally gave the maximum extraction yields in the two-step bioleaching process (100% of W, 100% of Fe, 92.7% of Mo, 66.43% of Ni, and 25% of Al). The main lixiviant in the bioleaching was shown to be gluconic acid. The red pigment produced by the fungus could also possibly act as an agent in Al leaching. © 2010 Elsevier Ltd. Source

Rajaeifar M.A.,University of Tehran | Ghobadian B.,Tarbiat Modares University | Safa M.,Lincoln University at Christchurch | Heidari M.D.,University of Tehran
Journal of Cleaner Production | Year: 2014

In this study the energy consumption and CO2 emissions of biodiesel production from soybean in Golestan province of Iran were studied. For this purpose, the life-cycle process of biodiesel was considered as five stages of agricultural soybean production, soybean transportation, soybean crushing, biodiesel conversion, and its transportation. The results indicated that the total fossil energy consumption with coproduct allocation was 8617.7 MJ ha -1 and the renewable energy output content (biodiesel as the final outcome) was estimated as 16,991.4 MJ ha-1. The net energy gain (NEG) and the fossil energy ratio (FER) were calculated as 8373.7 MJ ha-1 and 1.97, respectively, which show soybean is a suitable energy crop for biodiesel production. Agricultural soybean production stage ranked the first in energy consumption among the five main stages where it consumed 50.56% of total fossil energy consumption in the biodiesel life-cycle process. The greenhouse gas (GHG) emissions data analysis revealed that the total GHG emission was 1710.3 kg CO2eq ha-1 which biodiesel production life-cycle was only account for 311.96 kg CO2eq ha-1 if the mass allocation is considered. Overall, biodiesel production from soybean in Iran can be considered as a way to increase energy security in the near future. Also, soybean cultivation must be considered along with other common oilseeds cultivation in order to prevent food competition between biodiesel feedstocks and food production in Iran. © 2013 Elsevier Ltd. All rights reserved. Source

Abbaspur R.,Tarbiat Modares University
European Physical Journal C | Year: 2012

Noncommutative generalizations of a supersymmetry algebra in two dimensions have been introduced earlier in Abbaspur (Int. J. Mod. Phys. A 18:855-878, 2003; Mod. Phys. Lett. A 18:587-599, 2003). In this paper we present a field theoretic realization for these algebras in the context of N = 1 supersymmetric U(1) gauge theories in two dimensions. We also describe a possible generalization to 4-dimensional theories. © 2012 Springer-Verlag / Società Italiana di Fisica. Source

Yousefi R.,Islamic Azad University at Tehran | Saghafi K.,Shahed University | Moravvej-Farshi M.K.,Tarbiat Modares University
IEEE Transactions on Electron Devices | Year: 2010

In this paper, we investigate the transport properties of carbon nanotube field-effect transistors (CNTFETs), with a nonequilibrium Green's function (NEGF) method. Tunneling leakage currents with respect to gate voltages are known effects for MOSFET-like CNTFETs (MOSCNTs). To minimize this phenomenon, we have proposed a structure with a simple modification of the MOSCNT by using lightly doped regions between the intrinsic channel and the highly doped source and drain regions, which we call the lightly doped drain and source CNTFET (LDDS-CNTFET). Simulations have shown that LDDS-CNTFET characteristics are related to the lightly doped region concentration. In comparison with an MOSCNT and a linearly doped CNTFET (LD-CNTFET), an LDDS-CNTFET with appropriately doped lightly doped drain and source regions has demonstrated a larger on current (Ion), a larger on off ratio (Ion/Ioff), a superior ambipolar characteristic, a shorter delay time, and also a smaller powerdelay product. Furthermore, our results show that the channel length for an LDDS-CNTFET is shorter than that for an LD-CNTFET having the same off-state characteristics. Finally, the effect of the unavoidable Schottky barriers at the interface of the heavily doped source/drain regions and their metal electrodes has been taken into account. Simulations have demonstrated that these Schottky barriers have almost the same deteriorating effects on the characteristics for both LD-CNTFETs and LDDS-CNTFETs. Hence, all discussions regarding the superiority of the proposed structure are also valid in presence of the Schottky barriers. © 2010 IEEE. Source

Naffakh-Moosavy H.,Tarbiat Modares University
Philosophical Magazine | Year: 2016

The purpose of the present study is to introduce the weld quantitative solidification paths in the newly designed third-generation superalloys. The research has been conducted using both computational and experimental approaches. The model used the Scheil solidification relations to correlate the partitioning elements with their effects on the solidification paths. Accordingly, the k values were calculated for all the participating elements in the superalloy welds. The results of model demonstrated that these were very close to unity for austenite former elements, i.e. Ni, Co, Cr and Fe, while the other elements such as Ti, Nb and Mo displayed a significant tendency for segregation. The mathematical equations were calculated for weld solidification paths of superalloys. In all the welds, a remarkable segregation behaviour was observed, especially for Nb and Ti. The solidification path equations predicted type and amount of secondary phases. The solidification paths were compared with eutectic reactions (Formula presented.), and (Formula presented.), on the basis of the Ni–Ti–C and Ni–Nb–C ternary phase diagrams. Both the experimental measurements and microstructural observations of eutectics exhibited an appropriate accordance with the solidification paths obtained by model calculations. © 2016 Taylor & Francis Source

Nasiri S.H.,Islamic Azad University at Tehran | Moravvej-Farshi M.K.,Tarbiat Modares University | Faez R.,Sharif University of Technology
IEEE Electron Device Letters | Year: 2010

We present a Nyquist stability criterion based on transmission line modeling for graphene nanoribbon (GNR) interconnects. This is the first instance that such an analysis has been presented for GNR, so far. In this analysis, the dependence of the degree of relative stability for multilayer GNR (MLGNR) interconnects on the geometry of each ribbon has been acquired. It is shown that, increasing the length and width, MLGNR interconnects become more stable. © 2006 IEEE. Source

Shidpour R.,Sharif University of Technology | Manteghian M.,Tarbiat Modares University
Nanoscale | Year: 2010

In this study a low-width MoS2 ribbon has been used for probing the electronic structure and local magnetic moment near vacancies. A theoretical study with the full-potential Density Functional Theory (DFT) approach (Wien2K code) have shown that when the dimension of MoS2 is reduced from 2-D to 1-D the nonmagnetic semi-conductor MoS2 becomes a magnetic conductor. Our study has shown that a vacancy on the S-edge with 50% coverage intensifies the magnetization of the edge of the MoS2 nanoribbon but such a vacancy on S-edge with 100% coverage causes this magnetic property to disappear. It is concluded that in both of them, there are positive or negative strong gradients of local magnetic moment near the vacancy. This may explain why lattice defects are essential for catalysis processes. © 2010 The Royal Society of Chemistry. Source

Sajadieh M.S.,Amirkabir University of Technology | Fallahnezhad M.S.,University of Yazd | Khosravi M.,Tarbiat Modares University
International Journal of Production Economics | Year: 2013

This paper considers an integrated production-inventory model for a three-stage supply chain involving multiple suppliers, multiple manufacturers and multiple retailers. The suppliers/manufacturers produce the raw materials/final goods at a finite rate and deliver the materials/goods in a number of batches to the manufacturers/retailers. We analyze the problem where the lead times from the manufacturers to the retailers are stochastic and shortage is allowed. We also explicitly include the transportation costs from the manufacturers to the retailers into the model. The numerical analysis shows that the coordination mechanism employed is more beneficial for the cases with less unpredictable lead times, lower shortage prices, and no transportation cost. © 2013 Elsevier B.V. Source

Dashti R.,Iran University of Science and Technology | Yousefi S.,Tarbiat Modares University
Reliability Engineering and System Safety | Year: 2013

Asset management (AM) is composed of distribution system activities that lead to realize the system administration targets based on the stakeholders' benefits and correspondingly satisfying them. In this paper, asset management structure is represented and employing the AM structure, asset management processes are proposed. Furthermore, corresponding revisory actions are represented based on distribution asset wastages in order to structure a novel reliability based asset assessment model. The proposed model has been applied in a real distribution company, which provides 1 million customers with their requisite electrical energy. Crown Copyright © 2012 Publishedby Elsevier Ltd.All rights reserved. Source

Rezghi M.,Tarbiat Modares University | Obulkasim A.,Erasmus Medical Center
Expert Systems with Applications | Year: 2014

Principal component analysis (PCA) is one of the powerful dimension reduction techniques widely used in data mining field. PCA tries to project the data into lower dimensional space while preserving the intrinsic information hidden in the data as much as possible. Disadvantage of PCA is that, extracted principal components (PCs) are linear combination of all features, hence PCs are may still contaminated with noise in the data. To address this problem we propose a modified version of PCA called noise free PCA (NFPCA), in which regularization is introduced during the PCs extraction step to mitigate the effect of noise. Potentials of the proposed method is assessed in two important application of high-dimensional molecular data: classification and survival prediction. Multiple publicly available real-world data sets are used for this illustration. Experimental results show that, the NFPCA produce highly informative than the ordinary PCA method. This is largely due to the fact that the NFPCA suppress the effect of noise in the PCs more efficiently with minimum information lost. The NFPCA is a promising alternative to existing PCA approaches not only in terms of highly informative PCs, but also its relatively cheap computational cost. © 2014 Elsevier Ltd. All rights reserved. Source

Asl B.M.,Tarbiat Modares University
Ultrasonic Imaging | Year: 2016

In recent years, adaptive minimum-variance (MV) beamforming has been successfully applied to medical ultrasound imaging, resulting in simultaneous improvement in imaging resolution and contrast. MV has high resolution and hence can provide accurate estimates of the target locations. However, the MV amplitude estimates are significantly biased downward, especially when occurring the errors in model parameters. The amplitude and phase estimation (APES) beamformer gives much more accurate amplitude estimates at the target locations, but at the cost of lower resolution. To reap the benefits of both MV and APES, we have proposed a modified APES (MAPES) beamformer by adding a parameter which controls the trade-off between spatial and amplitude resolutions. We have also proposed an adaptive beamformer which combines the MV and APES. The proposed beamformer first estimates the peak locations using the MV estimator and then refines the amplitude estimates at these locations using the MAPES estimator. By using simulated and experimental data-point targets as well as cyst phantoms-we show the efficacy of the proposed beamformers. © 2016 The Author(s). Source

MohammadTaghvaei N.,Ahvaz Jundishapur University of Medical Sciences | Taheripak G.,Tehran University of Medical Sciences | Taghikhani M.,Tarbiat Modares University | Meshkani R.,Tehran University of Medical Sciences
Cellular Signalling | Year: 2012

Palmitate induces PTP1B expression in skeletal muscle cells. The purpose of this study was to investigate the mechanisms responsible for palmitate-induced PTP1B expression in mouse skeletal muscle cells. Three truncated fragments of PTP1B promoter were cloned into PGL3-basic vector and the promoter activity of PTP1B was assessed in C2C12 cells exposed to palmitate either in the presence or in the absence of several inhibitors to study the biochemical pathways involved. EMSA was performed to examine binding of NF-κB to NF-κB consensus sequence and PTP1B oligonucelotides in the cells treated with palmitate. Lentiviral PTP1B-shRNA was used to knockdown PTP1B in myotubes. The phosphorylation and protein levels of IRS-1 and Akt were detected by western blot. 0.5. mM palmitate induced PTP1B promoter activity in fragment -1715/+. 59 by 50% (p < 0.01). Palmitate increased NF-κB binding to both NF-κB consensus sequence and one NF-κB sequence (-920 to -935) in PTP1B promoter. Incubation of C2C12 cells with different concentrations of C2-ceramide enhanced PTP1B promoter activity dose-dependently. Inhibitors of de novo ceramide synthesis prevented palmitate-induced PTP1B promoter activity in myotubes. In addition, inhibitor of JNK pathway prevented ceramide-induced PTP1B promoter activity in myotubes. Knockdown of PTP1B also prevented ceramide-reduced IRS-1 and Akt phosphorylations in the myotubes. Exposure of the cells to PMA and calphostin C, an inhibitor of PKC, did not affect the activity of PTP1B promoter. Our data provide the evidence that the mechanism by which palmitate increased the expression of PTP1B seems to be through a mechanism involving the activation of ceramide-JNK and NF-κB pathways. © 2012 Elsevier Inc. Source

Arefi M.,University of Kashan | Rahimi G.H.,Tarbiat Modares University
Smart Structures and Systems | Year: 2014

The present study deals with two dimensional electro-elastic analysis of a functionally graded piezoelectric (FGP) cylinder under internal pressure. Energy method and first order shear deformation theory (FSDT) are employed for this purpose. All mechanical and electrical properties except Poisson ratio are considered as a power function along the radial direction. The cylinder is subjected to uniform internal pressure. By supposing two dimensional displacement and electric potential fields along the radial and axial direction, the governing differential equations can be derived in terms of unknown electrical and mechanical functions. Homogeneous solution can be obtained by imposing the appropriate mechanical and electrical boundary conditions. This proposed solution has capability to solve the cylinder structure with arbitrary boundary conditions. The previous solutions have been proposed for the problem with simple boundary conditions (simply supported cylinder) by using the routine functions such as trigonometric functions. The axial distribution of the axial displacement, radial displacement and electric potential of the cylinder can be presented as the important results of this paper for various non homogeneous indexes. This paper evaluates the effect of a local support on the distribution of mechanical and electrical components. This investigation indicates that a support has important influence on the distribution of mechanical and electrical components rather than a cylinder with ignoring the effect of the supports. Obtained results using present method at regions that are adequate far from two ends of the cylinder can be compared with previous results (plane elasticity and one dimensional first order shear deformation theories). Copyright © 2014 Techno-Press, Ltd. Source

Shirmohammadi R.,Tarbiat Modares University
Nanoscale and Microscale Thermophysical Engineering | Year: 2011

The thermal response predicted by hyperbolic heat conduction model is studied for a microspherical particle exposed to laser pulse heating. Using the obtained analytical solution, the temperature distribution, propagation, and reflection of the temperature wave due to such a heat pulse is investigated for different thermal relaxation times and laser pulse durations. The effect of geometry on the temperature profile is also studied, and the results of the hyperbolic and Fourier model are compared. The solution and analysis are expected to be useful for selecting suitable parameters such as laser pulse duration and particle size in experimental research and practical works. Copyright © Taylor &Francis Group, LLC. Source

Arefi M.,University of Kashan | Khoshgoftar M.J.,Tarbiat Modares University
Smart Structures and Systems | Year: 2014

The present paper develops piezo-thermo-elastic analysis of a thick spherical shell for generalized functionally graded piezoelectric material. The assumed structure is loaded under thermal, electrical and mechanical loads. The mechanical, thermal and electrical properties are graded along the radial direction based on a power function with three different non homogenous indexes. Primarily, the non homogenous heat transfer equation is solved by applying the general boundary conditions, individually. Substitution of stress, strain, electrical displacement and material properties in equilibrium and Maxwell equations present two non homogenous differential equation of order two. The main objective of the present study is to improve the relations between mechanical and electrical loads in hollow spherical shells especially for functionally graded piezoelectric materials. The obtained results can evaluate the effect of every non homogenous parameter on the mechanical and electrical components. Copyright © 2014 Techno-Press, Ltd. Source

Hosseini-Zori M.,Iran Institute for Color Science and Technology | Taheri-Nassaj E.,Tarbiat Modares University
Journal of Alloys and Compounds | Year: 2012

The hematite as a natural and non toxic red inorganic pigment has been known since prehistoric times but color shade of hematite becomes unstable with temperature and need to protect with a suitable matrix. The best red shades are obtained by the inclusion of hematite in silica matrixes. A co-precipitation method has been applied in order to improve the inclusion efficiency of hematite into silica crystals; iron sulfate was used as Fe precursor and precipitating agent was ammonia. Effects of the single flux agent (NaF and NaCl) and binary flux agent (NaF·NaCl), have been studied. Continuous changes in color were measured by comparing L*-a*-b* values of the heated samples. TEM analysis on heat treated powders shows some hematite single crystals that were occluded with silica crystals successfully. Due to its chemical and thermal stability, the hematite/silica pigment may be considered as a suitable red pigment for ceramic manufacturing by fast firing cycles. © 2011 Elsevier B.V. All rights reserved. Source

Hadad M.,Islamic Azad University at Dehaghan | Sadeghi B.,Tarbiat Modares University
Journal of Cleaner Production | Year: 2013

A number of studies have shown that compared to dry machining; MQL technique substantially enhances cutting performance in terms of increasing tool life and improving the quality of the machined parts. But, there have been a few investigations about the influence of process parameters on the results, such as MQL nozzle position and cutting parameters (cutting speed, depth of cut and feed). The current study aims to show through experiment, the effects of the above parameters on turning performance such as machining forces, surface roughness and temperature. Furthermore, this paper presents a new method to calculate average temperatures and the heat partition to the tool, workpiece and chip during MQL turning. This model also can be used for other turning operations such as dry and conventional wet turning processes. In other words, to more accurately predict machining temperatures and heat fluxes, convection heat transfer coefficient of MQL/fluid in the rake and flank faces of the tool have been made to the thermal model. The tool-chip interface temperature of turning AISI 4140 steel in which the oil mist is supplied from both nozzles to the rake and flank faces is approximately 350 C lower than that in dry turning. If the oil mist is supplied only to rake face, the tool temperature is about 200 C lower than that in dry turning. Additionally, in wet turning, the tool-chip interface temperature is about 300 C lower than that in dry turning. © 2013 Elsevier Ltd. All rights reserved. Source

Fakhimi A.,New Mexico Institute of Mining and Technology | Fakhimi A.,Tarbiat Modares University | Lanari M.,New Mexico Institute of Mining and Technology
Computers and Geotechnics | Year: 2014

A numerical model is proposed for the simulation of rock blasting. A bonded particle system is utilized to mimic the behavior of rock. The particles interact at the contact points through normal and shear springs to simulate rock elasticity. To withstand the deviatoric stresses, the particles are glued to each other. If the applied force exceeds the contact strength, local failure occurs and microcracks are developed in the synthetic rock. For simulation of gas flow, the smooth particle hydrodynamic method is implemented. The interaction of gas particles with the rock grains is assumed to follow a perfect plastic collision model in which the initial momentum of the colliding particles is preserved. A detailed examination of the interaction of gas with blast hole is investigated. It is shown that the proposed hybrid model is capable of simulating the induced shock waves in the gas together with wave propagation in the rock material. The model successfully mimics crack propagation in rock. In particular, the crushed zone around the borehole, radial cracks, and surface spalling are all captured successfully. The results of numerical analysis suggest that gas-rock interaction can, in fact, generate a few successive compressive waves in the rock specimen, causing further extension of radial cracks with time as the weaker secondary and tertiary waves interact with the crack tips. © 2013 Elsevier Ltd. Source

Afazeli H.,University of Tehran | Jafari A.,University of Tehran | Rafiee S.,University of Tehran | Nosrati M.,Tarbiat Modares University
Renewable and Sustainable Energy Reviews | Year: 2014

Fossil fuel resources are severely limited and their combustion is a major source of environmental pollution. As a result, scientists avidly seek alternatives to fossil fuels, and biomass can be a viable alternative source of energy. Anaerobic digestion is one of way of converting biomass to biogas. Slaughterhouse wastes and animal husbandry residues are from among the organic waste types utilized to generate biogas. Every year, large amounts of livestock waste discharges and slaughterhouse waste materials are produced worldwide, which provoke environmental pollution and are thus a cause of much concern. In lieu of what is discussed, it is intelligent to use animal wastes to generate biogas and hence reduce pollution. In view of that, the researchers in this study intend to investigate biogas production potential from animal manure in Iran. To this aim, biogas production potential from heavy and light livestock and poultry wastes were examined. Slaughterhouse wastes, containing rumen, intestines, stomach and blood from heavy and light livestock, and also poultry blood were examined. The results indicate that biogas production potential from the available livestock manure in this country is 8600 million m3 per year, 70% of which is obtained from heavy livestock, 23% of it from poultry, and only 7% from light livestock. Biogas yields potential from slaughterhouse wastes in Iran is approximately 54 million m3 per annum of which 40% is produced from light livestock rumen, 24% from heavy livestock rumen, 17% from heavy livestock blood, 14% from poultry blood, and 5% from light livestock blood. Tehran Province, as the capital, had the greatest potential for biogas production from slaughterhouse waste; that is about 9 million m3. From among all other provinces in Iran, Mazandaran Province had the greatest potential, with 828 million m3 biogas yield per year. © 2014 Elsevier Ltd. Source

Heidarzadeh M.,Tarbiat Modares University | Kijko A.,University of Pretoria
Natural Hazards | Year: 2011

A probabilistic tsunami hazard assessment is performed for the Makran subduction zone (MSZ) at the northwestern Indian Ocean employing a combination of probability evaluation of offshore earthquake occurrence and numerical modeling of resulting tsunamis. In our method, we extend the Kijko and Sellevoll's (1992) probabilistic analysis from earthquakes to tsunamis. The results suggest that the southern coasts of Iran and Pakistan, as well as Muscat, Oman are the most vulnerable areas among those studied. The probability of having tsunami waves exceeding 5 m over a 50-year period in these coasts is estimated as 17.5%. For moderate tsunamis, this probability is estimated as high as 45%. We recommend the application of this method as a fresh approach for doing probabilistic hazard assessment for tsunamis. Finally, we emphasize that given the lack of sufficient information on the mechanism of large earthquake generation in the MSZ, and inadequate data on Makran's paleo and historical earthquakes, this study can be regarded as the first generation of PTHA for this region and more studies should be done in the future. © 2010 Springer Science+Business Media B.V. Source

Shadidi B.,Bu - Ali Sina University | Yusaf T.,University of Southern Queensland | Alizadeh H.H.A.,Bu - Ali Sina University | Ghobadian B.,Tarbiat Modares University
Applied Energy | Year: 2014

Diesohol fuel is a mixture of diesel and bioethanol fuels in which the ratio of bioethanol is less than 15%. In this research work, performance of a tractor engine (Massey Ferguson 399) using diesohol fuel was investigated. In these circumstances, the concentration of UHC and CO2 emissions in the exhaust pipe were measured and analyzed. The engine was run at several speeds (1600-2000rpm). The obtained results reveal that, when using diesohol fuels, the power and torque of the MF-399 tractor engine are increased by 3.17-8.50% and 1.75-10.28% respectively when compared to diesel fuel. This is due to a relatively more complete combustion of ethanol because of its high oxygen content. The fuel consumption and specific fuel consumption are also increased by 7.32-15.81% and 4.37-7.44% respectively due to low calorific value of ethanol compared to diesel fuel. The analysis showed that when diesohol is used, the rate of UHC is decreased but CO2 emission is increased. In brief, by using diesohol fuels, especially E6 blend in comparison to diesel fuel, engine performance and emissions are improved without any changes in engine structure for diesohol application. © 2013 Elsevier Ltd. Source

Noroozi O.,Wageningen University | Weinberger A.,Saarland University | Biemans H.J.A.,Wageningen University | Mulder M.,Wageningen University | Chizari M.,Tarbiat Modares University
Computers and Education | Year: 2013

Learning to argue is prerequisite to solving complex problems in groups, especially when they are multidisciplinary and collaborate online. Environments for Computer-Supported Collaborative Learning (CSCL) can be designed to facilitate argumentative knowledge construction. This study investigates how argumentative knowledge construction in multidisciplinary CSCL groups can be facilitated with a transactive discussion script. The script prompts learners to paraphrase, criticize, ask meaningful questions, construct counterarguments, and propose argument syntheses. As part of a laboratory experiment, 60 university students were randomly assigned to multidisciplinary dyads based on their disciplinary backgrounds (i.e. water management or international development studies). These dyads were randomly assigned to a scripted (experimental) or non-scripted (control) condition. They were asked to analyse, discuss, and solve an authentic problem case related to both of their domains, i.e. applying the concept of community-based social marketing in fostering sustainable agricultural water management. The results showed that the transactive discussion script facilitates argumentative knowledge construction during discourse. Furthermore, learners assigned to the scripted condition acquired significantly more domain-specific and domain-general knowledge on argumentation than learners assigned to the unscripted condition. We discuss how these results advance research on CSCL scripts and argumentative knowledge construction. © 2012 Elsevier Ltd. All rights reserved. Source

Teymourian H.,Tarbiat Modares University | Salimi A.,University of Kurdistan | Hallaj R.,University of Kurdistan
Biosensors and Bioelectronics | Year: 2012

Fe 3O 4 magnetic nanoparticles were in situ loaded on the surface of multiwalled carbon nanotubes (MWCNTs) by a simple coprecipitation procedure. The resulting Fe 3O 4/MWCNTs nanocomposite brings new capabilities for electrochemical sensing by combining the advantages of Fe 3O 4 magnetic nanoparticles and MWCNTs. It was found that Fe 3O 4 has redox properties similar to those of frequently used mediators used for electron transfer between NADH and electrode. The cyclic voltammetric results indicated the ability of Fe 3O 4/MWCNTs modified GC electrode to catalyze the oxidation of NADH at a very low potential (0.0mV vs. Ag/AgCl) and subsequently, a substantial decrease in the overpotential by about 650mV compared with the bare GC electrode. The catalytic oxidation current allows the stable and selective amperometric detection of NADH at an applied potential of 0.0mV (Ag/AgCl) with a detection limit of 0.3μM and linear response up to 300μM. This modified electrode can be used as an efficient transducer in the design of biosensors based on coupled dehydrogenase enzymes. Lactate dehydrogenase (LDH) and NAD + were subsequently immobilized onto the Fe 3O 4/MWCNTs nanocomposite film by covalent bond formation between the amine groups of enzyme or NAD + and the carboxylic acid groups of the Fe 3O 4/MWCNT film. Differential pulse voltammetric detection of lactate on Fe 3O 4/MWCNT/LDH/NAD + modified GC electrode gives linear responses over the concentration range of 50-500μM with the detection limit of 5μM and sensitivity of 7.67μAmM -1. Furthermore, the applicability of the sensor for the analysis of lactate concentration in human serum samples has been successfully demonstrated. © 2011 Elsevier B.V. Source

Kazemipour A.,Islamic Azad University | Khormali O.,Tarbiat Modares University
Journal of Computational and Theoretical Nanoscience | Year: 2012

The vertex and edge versions of P I index were introduced in last years. In this paper, we introduce a new edge version for P I index and at following we compute this new index for some nanotubes. Copyright © 2012 American Scientific Publishers. Source

Mohammadi A.,University of Bojnord | Manteghian M.,Tarbiat Modares University | Mohammadi A.H.,Institute Of Recherche En Genie Chimique Et Petrolier Irgcp | Mohammadi A.H.,University of KwaZulu - Natal
Journal of Chemical and Engineering Data | Year: 2013

One of the limitations in the process of hydrate formation to benefit its positive application is high pressure and low temperature conditions. Design and construction of a unit with the aforementioned conditions is therefore expensive and unsafe. Thus, an investigation of methods for moderation of hydrate formation conditions seems to be very important. As mentioned in literature, utilization of ammonium salts in water normally promotes the hydrate formation conditions. One of these salts is tetra-n-butylammonium fluoride (TBAF). In this research, the dissociation data of semiclathrate hydrates for the systems of methane + TBAF + water, carbon dioxide + TBAF + water, and nitrogen + TBAF + water have been measured and reported. Experimental measurements were performed at three concentrations of TBAF, that is, (0.02, 0.05, and 0.15) mass fraction. A comparison of hydrate dissociation data in the presence or absence of TBAF shows the promotion effect of TBAF on methane, carbon dioxide, and nitrogen hydrate formation. By increasing the concentration of TBAF from (0.02 to 0.15) mass fraction, its promotion effect increases, and the p-T curves of the double gas + TBAF semiclathrate systems shift to the low pressure and high temperature regions (moderate conditions). Results of the experiments show that, contrary to clathrate hydrates, a small increase in temperature of semiclathrate hydrates, studied herein, leads to a noticeable increase in dissociation pressure. © 2013 American Chemical Society. Source

Hamzeh A.,Tarbiat Modares University | Reti T.,Obuda University
Match | Year: 2014

For the structural characterization of a connected graph G with n vertices and m edges two novel graph irregularity measures are introduced, they are defined as IRM1(G)=M1(G)-4m2/n and IRM2(G)=M2(G)-4m3/n2 where M1(G) and M2(G) are the first and second Zagreb indices of graph G, respectively. For irregularity indices IRM1(G) and IRM2(G) of trees, unicyclic, bicyclic and tricyclic graphs, upper bounds as a function of vertex number n are given. Moreover, it has been proved, that if the Zagreb indices inequality M2(G)/m ≥ M1G)/n is fulfilled for a connected graph G, then the relation IRM2(G)/m ≥ IRM1G)/n holds for G, as well. Tests performed on the sets of dual graphs of C66 fullerene isomers verified that the topological invariant IRM2 has a good discriminatory power and can be successfully applicable to the stability prediction of fullerenes. Source

Uromeihy A.,Tarbiat Modares University | Farrokhi R.,Islamic Azad University at Tehran
Bulletin of Engineering Geology and the Environment | Year: 2012

Water leakage from a dam is always important, but particularly where the preservation of water is essential in semi-dry areas, such Iran. At Kamal-Saleh Dam, the rock mass rating (RMR) and geological strength index(GSI) systems were used to identify the quality of the rock mass, which is particularly important in a foliated material. The RMR results were compared with Lugeon tests undertaken in vertical and oblique holes along the dam foundation and abutments. Although the rock quality designation values could not be used to indicate the quality of the rock mass, they had a direct relationship with the Lugeon values. © 2011 Springer-Verlag. Source

Alembagheri M.,Tarbiat Modares University
Soil Dynamics and Earthquake Engineering | Year: 2016

The dynamics of a coupled concrete gravity dam-intake tower-reservoir water-foundation rock system is numerically studied considering two hollow slender towers submerged in reservoir of gravity dam. The system is investigated in the frequency-domain using frequency response functions of the dam and the towers, and in the time-domain using time-history seismic analysis under a real earthquake ground motion. The analyzes are separately conducted under horizontal and vertical ground motions. The coupled system is three-dimensionally modeled using finite elements by Eulerian-Lagrangian approach. It is shown that presence of the dam significantly influences the dynamic response of the towers under both horizontal and vertical excitations; however the dam is not affected by the towers. When the dam is present in the model, the water contained inside the towers has different effects if the foundation is rigid, but it alleviates the towers motion if the foundation is flexible. It is concluded that the effects of foundation interaction are of much importance in the response of tall slender towers when they are located near concrete gravity dams. © 2016 Elsevier Ltd. Source

Naffakh-Moosavy H.,Tarbiat Modares University
International Journal of Advanced Manufacturing Technology | Year: 2016

The goal of the current research is to investigate the weld mushy zone in the newly designed third-generation superalloys numerically and experimentally, in order to predict the weld mushy zone solidification temperature range and size and predict the weldability. The mathematical equations for interpretation of weld mushy zone temperature have been obtained. Also, the equations which calculate the distance of the weld mushy zones are extracted. The equations correlate the retained liquid fraction to the temperature and longitudinal coordination of weld centerline. The calculations indicated that welds containing high amount of Ti and Nb simultaneously display wider weld mushy zone temperature range and size, while welds containing only one of Nb or Ti exhibit shorter weld mushy zone temperature range and size. The mushy zone temperature range of weld containing 5.6 wt.% (Ti + Al), 2.7 wt.% Nb reaches to a maximum of 212 °C. The output of the experimental observations demonstrates an appropriate validity for the mushy zone modelling. According to the numerical and experimental results, the composition ranges of {5.2 ≤ Nb wt. % ≤ 5.6} /{1.7 ≤ (Ti + Al) wt. % ≤ 2.4}, and{0 ≤ Nb wt. % ≤ 0.5} /{9.3 ≤ (Ti + Al) wt. % ≤ 10 } offer the best weldability for the newly designed superalloys. © 2015, Springer-Verlag London. Source

Pourghasemi H.R.,Tarbiat Modares University | Pradhan B.,University Putra Malaysia | Gokceoglu C.,Hacettepe University
Natural Hazards | Year: 2012

The main goal of this study is to produce landslide susceptibility maps of a landslide-prone area (Haraz) in Iran by using both fuzzy logic and analytical hierarchy process (AHP) models. At first, landslide locations were identified by aerial photographs and field surveys, and a total of 78 landslides were mapped from various sources. Then, the landslide inventory was randomly split into a training dataset 70 % (55 landslides) for training the models and the remaining 30 % (23 landslides) was used for validation purpose. Twelve data layers, as the landslide conditioning factors, are exploited to detect the most susceptible areas. These factors are slope degree, aspect, plan curvature, altitude, lithology, land use, distance from rivers, distance from roads, distance from faults, stream power index, slope length, and topographic wetness index. Subsequently, landslide susceptibility maps were produced using fuzzy logic and AHP models. For verification, receiver operating characteristics curve and area under the curve approaches were used. The verification results showed that the fuzzy logic model (89. 7 %) performed better than AHP (81. 1 %) model for the study area. The produced susceptibility maps can be used for general land use planning and hazard mitigation purpose. © 2012 Springer Science+Business Media B.V. Source

Kashan A.H.,Tarbiat Modares University
CAD Computer Aided Design | Year: 2015

Due to the law of reflection, the converging and diverging behavior of concave and convex mirrors causes that curved mirrors show different image types. The optics inspired optimization (OIO) is a recently proposed algorithm for unconstrained optimization which treats the surface of the function to be optimized as a wavy mirror in which each peak is assumed to reflect as a convex mirror and each valley to reflect as a concave one. Each individual is treated as an artificial light point that its glittered ray is reflected back by the function surface, given that the surface is convex or concave, and the artificial image (a new solution) is formed based on mirror equations adopted from Optics. There are several constraint handling techniques which have been proposed for handling infeasible solutions. However, these techniques may suffer from problem dependency, no unique way for designing their operators, no unique way for updating their internal parameters, increasing the computational complexity, etc. To equip OIO with a mechanism to handle constraints and to avoid the drawbacks of typical techniques, a feasibility measure is used beside the objective function value to bias the search toward feasible regions. Such a consideration requires to modify several modules in the basic OIO algorithm. To increase the probability to generate better solutions, a number of alternative solutions are produced from each individual and one is selected based on the sequential use of modified Deb's tournament selection. Besides, Deb's tournament selection rule is used in place of the greedy selection in basic OIO, along with allowing the survival of individuals with a good value of the objective function, regardless of their feasibility. Performance of the proposed algorithm is compared with a number of noticeable algorithms such as COPSO, ECHT-EP2, αSimplex etc, on CEC 2006 and CEC 2010 set of benchmark problems and on a set of mechanical design optimization problems. Results demonstrate that the proposed algorithm performs the global optimization task very well and competitive. Such an outcome encourages that further developments and applications of OIO would be worth to realize its full potency in the future studies. © 2014 Elsevier Ltd. All rights reserved. Source

Koohestani M.,Islamic Azad University at Tehran | Golpour M.,Tarbiat Modares University
Microwave and Optical Technology Letters | Year: 2010

This letter presents a rectangular slot antenna with a novel coplanar waveguide fed diamond patch covering frequency range from 2.27 to 10.63 GHz based on S11 < - 10 dB, 129φ%. The fabricated antenna has a small size as high as 42 x 42 mm2. The measured results are in good agreement with simulation results. The measured radiation patterns are nearly omni-directional over the most of the frequency bandwidth. The antenna gain ranges from 1.6 to 7.6 dBi. The simple structure, compact size, and good characteristics make the antenna easy to use in commercial ultra wideband systems. © 2009 Wiley Periodicals, Inc. Source

Barati A.H.,Kurdistan University of Medical Sciences | Mokhtari-Dizaji M.,Tarbiat Modares University
Ultrasound in Medicine and Biology | Year: 2010

Sonodynamic therapy (SDT) is a new modality in cancer therapy and it is based on preferential uptake and/or retention of a sonosensitizing drug in tumor tissues and subsequent activation of the drug by ultrasound. The dose fractionation effect in radiation therapy has been known for more than a century, but it is not reported in SDT so far. In this study, the in vivo antitumor effect of the simultaneous dual-frequency ultrasound (1 MHz and 150 kHz) at low-level intensity (cumulative ISATA = 2.2W/cm2; total energy density 3960J/cm2; for 30 min sonication) in combination with the sonosensitizer of photofrin (PF) (sodium porfimer) was investigated in dose fractionation regime in a spontaneous murine model of breast adenocarcinoma in Balb/c mice. The tumor-bearing mice were divided into six groups (n = 8 to 10): Untreated groups included control and sham; experimental groups were treated with 5 mg/kg intravenous injection of PF alone, with combined PF and ultrasound for 30-min sonication in one fraction at 24 h after PF administration; with combined PF and ultrasound for 30 min sonicatin in three fraction at 18, 24 and 30 h after PF administration; and finally with combined PF and ultrasound for 30 min sonication in five fraction at 12, 18, 24, 30 and 36 h after PF administration. The tumor growth delay (TGD) parameters and the percent of apoptotic index AI (%) were measured in treated and untreated groups. The results show that the TGD parameters in treatment groups with combined drug and ultrasound fractionation mode were significantly different compared with other groups (p < 0.05). Also the sonodynamic ultrasound dose fractionation in five fractions is more effective than of the three-fraction regime. The AI of the tumor tissues treated by ultrasound dose fractionation was also significantly higher in the other groups (p < 0.05), in which the AI (%) in the group treated with five fractions was higher with respect to group treated with 3 fractions (11.56 ± 1.2; 8.7 ± 0.87), respectively. In conclusion, the ultrasound dose fractionation can be useful in therapeutic effect in SDT and may have future clinical applications. © 2010. Source

Haroonabadi H.,Islamic Azad University at Tehran | Haghifam M.-R.,Tarbiat Modares University
Applied Soft Computing Journal | Year: 2011

Deregulation policy has caused some changes in the concepts of power systems reliability assessment and enhancement. In the present research, generation reliability is considered, and a method for its assessment is proposed using intelligent systems. Also, due to the stochastic behavior of power market and generators' forced outages, Monte Carlo Simulation is used for reliability evaluation. Generation reliability merely focuses on the interaction between generation complex and load. Therefore, in this research, based on the type of market and concentration, reserve margin and various future times, a Neuro-Fuzzy system is proposed for evaluation of generation reliability, which is valid and usable for all kinds of power pool markets. Finally, the proposed method is assessed on IEEE-Reliability Test System with satisfactory results. The results further showed that if market becomes more concentrated or price elasticity of demand increases, reliability will improve. © 2011 Elsevier B.V. All rights reserved. Source

Koohestani M.,Islamic Azad University at Tehran | Golpour M.,Tarbiat Modares University
IET Microwaves, Antennas and Propagation | Year: 2010

In this study, a novel compact microstrip antenna with an ultra wide bandwidth is presented. The proposed antenna is a U-shaped square patch combined with two parasitic tuning stubs which is fed by a coplanar waveguide (CPW). The total size of the fabricated antenna is 24×28×0.787 mm3. The dimensional parameters for the antenna are introduced and their effects on the frequency characteristic have been investigated through a parametric study. Simulated and experimental results indicate that the antenna achieved an ultra wideband impedance bandwidth (S11 < -10 dB) as high as 129%. The radiation patterns of the antenna are measured and presented. The simulated results show good agreement with the measured results. The measured gains range from 1.6 to 5.3 dBi against frequency. These characteristics make the antenna suitable for UWB applications. © 2010 The Institution of Engineering and Technology. Source

Mahini M.R.,Persian Gulf University | Moharrami H.,Tarbiat Modares University | Cocchetti G.,Polytechnic of Milan
Computers and Structures | Year: 2014

This paper is concerned with nonlinear analysis of frames composed of softening materials. The previously proposed dissipated energy maximization approach is extended to determine non-holonomic solution of such frames. The adopted assumptions are: linear kinematics, lumped plasticity with softening behavior, piecewise-linear yield functions, associate flow rule and isotropic evolution with a three phase linear softening rule. The approach is based on a mathematical programming formulation. The solution procedure is discussed and presented in a comprehensive flowchart. It is shown that this method has the ability of solving and tracing path dependent problems and detecting any possible bifurcation. © 2012 Elsevier B.V. All rights reserved. Source

Husseinzadeh Kashan A.,Tarbiat Modares University
Computers and Operations Research | Year: 2014

Due to the law of reflection, a concave reflecting surface/mirror causes the incident light rays to converge and a convex surface/mirror causes the light rays to reflect away so that they all appear to be diverging. These converging and diverging behaviors cause that the curved mirrors show different image types depending on the distance between the object and the mirror. We model such optical phenomena metaphorically into the searching process of numerical optimization by a new algorithm called optics inspired optimization (OIO). OIO treats the surface of the numerical function to be optimized as a reflecting surface in which each peak is assumed to reflect as a convex mirror and each valley to reflect as a concave one. Each individual is assumed to be an artificial object (or light point) that its artificially glittered ray is reflected back by the function surface, given that the surface is convex or concave, and the artificial image is formed (a candidate solution is generated within the search domain) based on the mirror equations adopted from physics of optics. Besides OIO, we introduce different variants of it, called ROIO (Rotation based OIO), and COIO (Convex combination based OIO) algorithms and conduct an extensive computational effort to find out the merit of the new algorithms. Our comparisons on benchmark test functions and a real world engineering design application (i.e., optimization of a centrifuge pump) demonstrate that the new algorithms are efficient and compete better than or similar to most of state of the art optimization algorithms with the advantage of accepting few input parameters. © 2014 Elsevier Ltd. Source

Rahmanian B.,Ferdowsi University of Mashhad | Pakizeh M.,Ferdowsi University of Mashhad | Mansoori S.A.A.,Ferdowsi University of Mashhad | Abedini R.,Tarbiat Modares University
Journal of Hazardous Materials | Year: 2011

In this study, micellar-enhanced ultrafiltration (MEUF) was applied to remove zinc ions from wastewater efficiently. Frequently, experimental design and artificial neural networks (ANNs) have been successfully used in membrane filtration process in recent years. In the present work, prediction of the permeate flux and rejection of metal ions by MEUF was tested, using design of experiment (DOE) and ANN models. In order to reach the goal of determining all the influential factors and their mutual effect on the overall performance the fractional factorial design has been used. The results show that due to the complexity in generalization of the MEUF process by any mathematical model, the neural network proves to be a very promising method in compared with fractional factorial design for the purpose of process simulation. These mathematical models are found to be reliable and predictive tools with an excellent accuracy, because their AARE was ±0.229%, ±0.017%, in comparison with experimental values for permeate flux and rejection, respectively. © 2010 Elsevier B.V. Source

Abedini R.,Tarbiat Modares University | Abedini A.,University of Regina
Petroleum Science and Technology | Year: 2011

The precipitation and deposition of crude oil polar fractions such as asphaltenes in petroleum reservoirs considerably reduce rock permeability and oil recovery. Therefore, it is of great importance to determine how and how much the asphaltenes precipitate as a function of pressure, temperature, and liquid phase composition. The authors designed and applied an Artificial Neural Network (ANN) model to predict the amount of asphaltene precipitation at a given operating condition. Among this training, the back-propagation learning algorithm with different training methods was used. The most suitable algorithm with an appropriate number of neurons in the hidden layer, which provides the minimum error, was found to be the Levenberg-Marquardt (LM) algorithm. An extensive experimental data for the amount of asphaltene precipitation at various temperatures (293-343 K) was used to create the input and target data for generating the ANN model. The predicted results of asphaltene precipitation from the ANN model was also compared with the results of proposed scaling equations in the literature. The results revealed that scaling equations cannot predict the amount of asphaltene precipitation adequately. With an acceptable quantitative and qualitative agreement between experimental data and predicted amount of asphaltene precipitation for all ranges of dilution ratio, solvent molecular weight and temperature was obtained through using ANN model. Copyright © Taylor & Francis Group, LLC. Source

Vafakhah M.,Tarbiat Modares University
Canadian Journal of Civil Engineering | Year: 2012

The present article aims to forecast streamflow by using artificial neural networks (ANNs), adaptive neuro-fuzzy inference system (ANFIS), and autoregressive moving average (ARMA). For this purpose, the daily streamflow time series of two hydrometry stations of Hajighoshan and Tamar on Gorgan River are used for two periods of 1983-2007 and 1974-2007, respectively. Root mean square error (RMSE) and correlation coefficient (R) statistics are employed to evaluate the performance of the ANNs, ANFIS, and ARMA models for forecasting streamflow (1 day ahead). Comparison of the results reveals that the ANFIS model outperforms the ARMA model. Based on the results of validation stage, for the forecasting 1 day ahead streamflow, ANN with RMSE = 0.028 m 3/s and R = 0.59 for the Hajighoshan station and RMSE = 0.013 m 3/s and R = 0.44 for the Tamar station were found to be superior to the ANFIS with RMSE = 1.98 m 3/s and R = 0.42 for the Hajighoshan station and RMSE = 2.18 m 3/s and R = 0.22 for the Tamar station. In addition, for 2 day and 3 day ahead streamflow forecasts, the ANN models show superiority in the accuracy of forecasting streamflow compared with the ANFIS models. Source

Farahpour M.M.,Tarbiat Modares University | Hessami K.,International Institute of Earthquake Engineering and Seismology
Journal of the Geological Society | Year: 2012

Several major zones across the Zagros fold-thrust belt have been interpreted as indicating that orogeny took place progressively from NE to SW through discrete orogenic episodes during Tertiary time. This paper uses field evidence of growth onlaps and angular unconformities within the Cretaceous stratigraphic column as well as existing geological maps and cross-sections to indicate that deformation started as early as the Late Aptian and folded the whole width of the Zagros belt simultaneously. Later events are indicated by folding at the end of the Cenomanian, and in the Late Turonian and Santonian. Following the Late Cretaceous deformation phases, the SE Zagros basin was divided into several longitudinal intra-shelf basins, which were separated by NW-SE-trending Cretaceous anticlines. However, with reference to our previous work, it can be suggested that each of the sub-basins was folded serially from NE to SW through a series of tectonic phases during the next episode of Zagros orogeny in Tertiary time. The change of deformation style from concomitant to serial folding, during the Cretaceous and Tertiary respectively, is attributed to the existence of the Hormuz Salt and shearing at the base of the former basin and its absence at the base of the Tertiary intra-shelf basins. Source

Zafarani H.,International Institute of Earthquake Engineering and Seismology | Soghrat M.,Tarbiat Modares University
Bulletin of the Seismological Society of America | Year: 2012

Physically based ground-motion prediction equations for soil and rock sites in the Zagros region have been developed based on the specific barrier model (SBM) used within the context of the stochastic model. Instead of direct timedomain simulation, random vibration theory was used to estimate measures of peak motion in terms of the pseudospectral velocity of anelastic harmonic oscillator with 5% viscous damping. To avoid the uncertainties, calibration of the source model uses a database of carefully selected strong motion data without ambiguity about the site condition. Therefore, only rock sites are selected for determining source parameters. Also, to avoid any inconsistencies caused by magnitude conversion formulas, we restricted the dataset only to events with available moment magnitudes. Regression analysis is performed using the random effects model that considers both interevent and intraevent variabilities to effectively deal with the problem of an unequal number of records from different earthquakes. No sign of self-similarity breakdown is observed between the source radius and its seismic moment. The local and global stress drops derived for the Zagros region (39 and 116 bars, respectively) are more consistent with the values obtained by other authors for an interplate regime than the values for an intraplate region. However, from the viewpoint of source heterogeneity (as the ratio of the stress drops is an indicator of the complexity of the source and heterogeneity of slip on the fault) the Zagros events, which have a stress-drop ratio of about three are more homogeneous than other interplate events. Stochastic simulations are then implemented to predict peak ground motion and response spectra parameters for rock and soil site conditions. Source

Imaanpur A.,Tarbiat Modares University
Journal of High Energy Physics | Year: 2011

We consider self-duality equation of U(1) gauge fields on Euclidean AdS4 space, and find a simple finite action solution. With a suitable ansatz, we are able to embed this solution into the 10d supergravity background of AdS4 × CP3. Further, we show that the solution can be uplifted to an exact solution in 11d supergravity background of AdS 4×SE7. © 2011 SISSA. Source

Degeneration of retinal ganglion cells (RGCs) is a common occurrence in several eye diseases. This study examined the functional improvement and protection of host RGCs in addition to the survival, integration and neuronal differentiation capabilities of anterior specified neural progenitors (NPs) following intravitreal transplantation. NPs were produced under defined conditions from human induced pluripotent stem cells (hiPSCs) and transplanted into rats whose optic nerves have been crushed (ONC). hiPSCs were induced to differentiate into anterior specified NPs by the use of Noggin and retinoic acid. The hiPSC-NPs were labeled by green fluorescent protein or a fluorescent tracer 1,1' -dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) and injected two days after induction of ONC in hooded rats. Functional analysis according to visual evoked potential recordings showed significant amplitude recovery in animals transplanted with hiPSC-NPs. Retrograde labeling by an intra-collicular DiI injection showed significantly higher numbers of RGCs and spared axons in ONC rats treated with hiPSC-NPs or their conditioned medium (CM). The analysis of CM of hiPSC-NPs showed the secretion of ciliary neurotrophic factor, basic fibroblast growth factor, and insulin-like growth factor. Optic nerve of cell transplanted groups also had increased GAP43 immunoreactivity and myelin staining by FluoroMyelin™ which imply for protection of axons and myelin. At 60 days post-transplantation hiPSC-NPs were integrated into the ganglion cell layer of the retina and expressed neuronal markers. The transplantation of anterior specified NPs may improve optic nerve injury through neuroprotection and differentiation into neuronal lineages. These NPs possibly provide a promising new therapeutic approach for traumatic optic nerve injuries and loss of RGCs caused by other diseases. Source

Azadegan A.,The New School | Patel P.C.,Ball State University | Zangoueinezhad A.,Tarbiat Modares University | Linderman K.,University of Minnesota
Journal of Operations Management | Year: 2013

Increasingly manufacturers implement lean practices to improve operational performance. In addition, manufacturers operate in ever more complex and volatile environments. This research investigates the effects of environmental complexity and dynamism on lean operations and lean purchasing practices. It empirically examines these relationships using archival and survey data from 126 manufacturers. The results show that environmental complexity positively moderates the effects of lean operations and lean purchasing on performance. However, environmental dynamism reduces the benefits of lean operations on performance, but enhances the benefits of lean purchasing on performance. Robustness tests further confirm the contingent effects of complexity and dynamism on lean operations and lean purchasing. This research offers a more nuanced understanding of the effect of external environmental context on lean practices, and suggests that practitioners should carefully consider the external environment when implementing different types of lean practices. © 2013 Elsevier B.V. All rights reserved. Source

Abadi A.T.B.,Tarbiat Modares University
World Journal of Gastroenterology | Year: 2016

Over three decades have passed since the discovery of Helicobacter pylori (H. pylori ), and yet many questions about its treatment remain unanswered. For example, there is no certainty regarding continued use of current antibiotic therapy against H. pylori . The bad news is that even combined regimens are also unable to eradicate bacterial colonization. The worst problem with H. pylori chemotherapy is that even if we identify the most successful regimen, it cannot eliminate the risk of re-infection. This problem is further complicated by the fact that clinicians have no information as to whether probiotics are useful or not. Moreover, to date, we have no large scale produced vaccine effective against H. pylori . Due to the relatively rapid and abundant dissemination of guidelines globally reported concerning management of gastric cancer prevention and therapeutic regimens, clinicians may choose a vaccine as better effective weapon against H. pylori . Therefore, a radical shift in adopted strategies is needed to guide ultimate decisions regarding H. pylori management. In light of failures in vaccine projects, we should identify better vaccine design targeting conserved/essential genes. The unique character and persistence of H. pylori pose obstacles to making an effective vaccine. Preferably, in developing countries, the best reasonable and logical approach is to recommend prophylactic H. pylori vaccine among children as an obligatory national program to limit primary colonization. Trying to produce a therapeutic vaccine would be postponed until later. In reality, we should not forget to prescribe narrow spectrum antibiotics. In the current review, I draw a route to define the best adopted strategy against this rogue bacterium. ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. Source

Sedghi M.,K. N. Toosi University of Technology | Aliakbar-Golkar M.,K. N. Toosi University of Technology | Haghifam M.-R.,Tarbiat Modares University
International Journal of Electrical Power and Energy Systems | Year: 2013

Multistage distribution network expansion because of load growth is a complex problem in distribution planning. The problem includes minimizing cost of objective function subject to technical constraints. The objective function consists of investment, operation and reliability costs. In this paper, HV/MV substations, main and reserve MV feeders, dispatchable DG sources and storage units are considered as possible solutions for multistage distribution expansion planning. A three-load level is used for variable load and some strategies are proposed for DG and storage units operation. A modified PSO algorithm is applied to solve the complex optimization problem. Numerical results of the case studies show the ability of the modification. Moreover, the proposed strategies improve the distribution network from both economical and reliability points of view compared with the other methods. ©2013 Elsevier Ltd.All rights reserved. Source

Motaghian H.,University of Tehran | Hassanzadeh A.,Tarbiat Modares University | Moghadam D.K.,University of Tehran
Computers and Education | Year: 2013

In many societies e-learning has become the main mechanism supporting distance education. Although e-learning efforts are considered to be a significant corporate investment, many surveys indicate high drop-out rates or failures. This research uses an integrated model in order to assessing the influence of IS-oriented, psychological and behavioral factors on instructors' adoption of web-based learning systems. Survey data collected from 115 university instructors were analyzed using structural equation modeling to examine the theoretical model. The research results show that perceived usefulness, perceived ease of use and system quality increase instructors' intention to use web-based learning systems; however, perceived usefulness is the most important factor affecting on intention and actual use of the system (adoption). © 2012 Elsevier Ltd. All rights reserved. Source

Amiri F.,Sharif University of Technology | Mousavi S.M.,Tarbiat Modares University | Yaghmaei S.,Sharif University of Technology
Separation and Purification Technology | Year: 2011

Statistically based experimental designs were applied to screen and optimize the bioleaching of spent hydrocracking catalyst by Penicillium simplicissimum. Eleven factors were examined for their significance on bioleaching using a Plackett-Burman factorial design. Four significant variables (pulp density, sucrose, NaNO3, and yeast extract concentrations) were selected for the optimization studies. The combined effect of these variables on metal bioleaching was studied using a central composite design (CCD). Second-order polynomials were established to identify the relationship between the recovery percent of the metals and the four significant variables. The optimal values of the variables for maximum metals bioleaching were as follows: pulp density (4.0%, w/v), sucrose (90 g/L), NaNO3 (2 g/L) and yeast extract (0.36 g/L). The maximum metals recovery percentages from the predicted models were 97.6% Mo, 45.7% Ni, and 14.3% Al. These values were in perfect agreement with the actual experimental values, which were (98.8 ± 0.9)% Mo, (46.5 ± 0.6)% Ni, and (13.7 ± 0.4)% Al. The growth kinetics of the fungus in the presence of the spent catalyst at various pulp densities (2-11%) and optimal condition was modeled using the modified Gompertz model. The kinetic parameters in the system were estimated using MATLAB R2008a. Results showed that the modified Gompertz model fit the experimental data well. The relationship between the specific growth rate and pulp density was found by modifying the Luong inhibition model which gave maximum specific growth rate of 0.034 day-1, optimal pulp density of 3.95% w/v and critical inhibitor concentration of 10.9% w/v. © 2011 Elsevier B.V. All rights reserved. Source

Based on theory of piezo-elasticity, bending behavior of functionally graded carbon nanotube reinforced composite (FG-CNTRC) cylindrical panel attached to thin piezoelectric layers subjected to thermal, mechanical loads and or electric field is investigated. It is assumed that thermo-elastic constants of the structure are independent of temperature gradient. In this paper, uniformly and various cases of functionally graded CNT distribution along the radial direction of host layer are considered. Governing differential equations are solved analytically by using the Fourier series expansion along axial and circumferential direction and state-space technique across the radial direction. Temperature, stress and displacement fields as well as induced electric voltage in sensor layer are obtained and used to study the thermo-piezoelastic behavior of hybrid FG-CNTRC cylindrical panel. Accuracy of present approach is validated by comparing the numerical results with the available reported results in literatures. Parametric studies are carried out to assess the effects of CNT volume fraction, case of CNT distribution along the radial direction, surface thermal/mechanical surface boundary conditions, applied voltage on the bending behavior of FG-CNTRC hybrid cylindrical panel. © 2016 Elsevier Ltd. Source

In this paper the bending behavior of a uniform distribution (UD) and a functionally graded carbon-nanotube-reinforced composite (FG-CNTRC) cylindrical panel embedded in piezoelectric layers is investigated. The hybrid cylindrical panel has simply supported boundary conditions and is subjected to mechanical load and electric excitation. The governing equations are based on the three-dimensional theory of elasticity. By using Fourier series expansion along the longitudinal and latitudinal directions for the stress and displacement fields, and the state space technique across the thickness direction, a closed form solution is derived. The accuracy of the present approach is validated by comparing the numerical results with the results obtained in published literature. Finally, the effects of volume fraction of CNTs, cases of CNT distribution, piezoelectric layer thickness, length to thickness ratio and mechanical and electrical loads on the static behavior of the hybrid cylindrical panel are also examined. © 2013 IOP Publishing Ltd. Source

Gholami A.,University of Tehran | Hosseini S.M.,Tarbiat Modares University
Signal Processing | Year: 2013

This paper introduces a novel method to combine total variation and ℓ2 regularizations to reconstruct piecewise smooth signals. The main idea is to consider the signal as a sum of two components: a piecewise constant component and a smooth component. For the solution of ill-posed problems, the Tikhonov method with a special stabilizer in the form of a sum of two different stabilizers is used: the total variation for the first component and the Sobolev norm for the second one. An iteratively re-weighted least squares technique is used as a fast and an efficient algorithm for minimization of the Tikhonov functional. A method is also presented for determining the regularization parameters. Numerical experiments, among the many performed, in denoising, deblurring, and compressed sensing demonstrate high performance of the new regularization for reconstruction of piecewise-smooth solutions with sharp discontinuities. © 2012 Elsevier B.V. Source

Khoshkholgh M.G.,Simula Research Laboratory | Mokari N.,Tarbiat Modares University | Shin K.G.,University of Michigan
IEEE Journal on Selected Areas in Communications | Year: 2013

This paper investigates the ergodic sum capacity of a spectrum-shared Multiple Access Channel (MAC). We assume that the secondary service (SS) only knows the channel distribution information (CDI) between its transmitters and the primary receivers. Availability of CDI results in collision incidences at the primary receivers because of conflicting levels of intolerable interference. We introduce the concept of collision probability constraint to manage the unexpected QoS degradation of primary service in the secondary resource allocation (RA). This RA problem is inherently difficult to solve and its objective function is not necessarily convex. Two well-known approaches, called Iterative Approach (IA) and Analytical Approach (AA), each with several cases/categories, are then used to find solutions. IA solves the problem iteratively by reconstructing convex optimization problems from the original (non-convex) one in a number of iterative loops until the collision probability constraints are satisfied. IA is shown to converge quickly to a suitable solution. Furthermore, by using a control parameter, the system designer can make a tradeoff between the speed of convergence and the ergodic sum capacity. AA, on the other hand, solves the RA problem by suggesting tractable versions of collision probability constraints. Unlike IA, AA does not require extra signaling between transmitters and the base station to tune parameters, thus facilitating the implementation of SS. Our in-depth simulations have shown the proposed approach to yield lower spectral efficiency than IA. © 1983-2012 IEEE. Source

Darvishi Cheshmeh Soltani R.,Arak University of Medical Sciences | Rezaee A.,Tarbiat Modares University | Khataee A.,University of Tabriz
Industrial and Engineering Chemistry Research | Year: 2013

The aim of this work was to enhance the efficiency of a photocatalytic process involving carbon black (CB)-modified ZnO nanoparticles using an electrochemical process consisting of powdered activated carbon (PAC), carbon nanotubes (CNTs), and CB-polytetrafluoroethylene (PTFE)-coated gas-diffusion cathode (GDC) to degrade Acid Red 18. Hydrogen peroxide generated by PAC-PTFE-, CNT-PTFE-, and CB-PTFE-coated GDC was 58.45, 100.9, and 112.3 μM, respectively. The efficiency of the combined process equipped with CB-PTFE-coated GDC was assessed as the function of different operational parameters. With the increase of initial pH from 3 to 10, decolorization efficiency decreased from 94.5% to 57.61%. Increasing the dye concentration from 2 to 20 mg/L led to a decrease in the decolorization efficiency from 100% to 50.45%. The increase of the current intensity from 30 to 300 mA resulted in increasing decolorization efficiency from 37.45% to 95.31%. TOC analysis showed 51.13% mineralization of 10 mg/L dye solution in 20 min. © 2013 American Chemical Society. Source

Ahmadi H.,Tarbiat Modares University
Research Journal of Applied Sciences, Engineering and Technology | Year: 2012

The solubility of gases is an important issue in the industries. Carbon Dioxide Through gas transmission line exists as sour gas therefore it is eliminated by solvent in industry. Carbone Dioxide is nonpolar molecule that has lower solubility in liquid solvent. In this study the solubility of carbon dioxide in some polar and nonpolar solvents (include Acetone, Acetic Acid, Benzene, Carbon Tetra Chloride, Chlorobenzene, Chloroform, Cyclo-hexane, Di-Methyl Formamid, Ethanol, Ethyl acetate, Methanol, NButanol, N-Heptane, N-Hexane) at atmospheric pressure and temperatures range from 5-35°C was determined. A laboratory unit was made for this experience and the solubility of CO 2 was reported. The solubility of carbon dioxide in these solvent was low due to unreactivity and nonpolarity nature of these material. The solubility of CO 2 in Ethyl Acetate and Methanol was highest and lowest respectively. This investigation showed that the solvent with carbonyl group have higher activity than other. © Maxwell Scientific Organization, 2012. Source

Ebrahimpour A.,Islamic Azad University at Tehran | Maerefat M.,Tarbiat Modares University
Energy Conversion and Management | Year: 2011

External shading affects the solar energy incident on a window and the transferred energy within the room through the window. In present study, the effect of advanced glazing and overhangs on the solar energy transmitted into or lost from the room through the fenestration areas have been evaluated for typical residential buildings in Tehran, using EnergyPlus× software. It was found that appropriate overhangs or side fins in the south, west and east windows would lead to the optimal reduction of the annual energy transferred into the buildings and can have an energetic behaviour equivalent to high performance glazing. The results have been summarized in a table to simple selecting the best window with different glazings, overhangs and side fins based on energy rating. © 2010 Elsevier Ltd. All rights reserved. Source

Naffakh-Moosavy H.,Tarbiat Modares University
International Journal of Minerals, Metallurgy and Materials | Year: 2016

The present research aims to establish a quantitative relation between microstructure and chemical composition (i.e., Ti, Al, and Nb) of newly designed nickel-based superalloys. This research attempts to identify an optimum microstructure at which the minimum quantities of γ/γ′ and γ/γ″ compounds are achieved and the best castability is predicted. The results demonstrate that the highest quantity of intermetallic eutectics (i.e., 41.5wt%) is formed at 9.8wt% (Ti + Al). A significant quantity of intermetallics formed in superalloy 1 (with a composition of γ − 9.8wt% (Ti + Al)), which can deteriorate its castability. The type and morphology of the eutectics changed and the amount considerably decreased with decreasing Ti + Al content in superalloy 2 (with a composition of γ − 7.6wt% (Ti + Al), 1.5wt% Nb). Thus, it is predicted that the castability would improve for superalloy 2. The same trend was observed for superalloy 4 (with a composition of γ − 3.7wt% (Ti + Al), 4.4wt% Nb). This means that the amount of Laves increases with increasing Nb (to 4.4wt%) and decreasing Ti + Al (to 3.7wt%) in superalloy 4. The best castability was predicted for superalloy 3 (with a composition of γ − 5.7wt% (Ti + Al), 2.8wt% Nb). © 2016, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg. Source

Rahdari A.H.,Tarbiat Modares University
Journal of Cleaner Production | Year: 2016

The surge of socio-economic and environmental problems in the recent decades have exacted a clarion call for transitioning to more sustainable and responsible business practices. Developing multiple bottom line performance evaluation systems, in order to track the progress made, is at the fulcrum of such a transition. The purpose of this study is to design a triangular rating system for multiple bottom line performance evaluation using corporate governance, corporate social responsibility, and corporate financial performance ratings. Furthermore, using a case study approach, the framework is tested in a high impact industry i.e. Iranian petrochemical industry. The result of the analyses showed no significant relationship among the three dimensions of the rating system which mainly stemmed from the failure of the examined market in adopting responsible business practices. Moreover, sensitivity analyses were conducted to account for any discrepancies in the outcomes as a result of using fuzzy numbers and weighting vectors. The study makes two major contributions. Theoretically, it proposes a triangular framework for performance evaluation using key performance indicators. Empirically, it applies the framework to a set of cases from the petrochemical industry by employing two prominent multi-Attribute decision making models using fuzzy sets. Finally, the study concludes that failing to integrate environmental, social, and governance measures into decision making processes, in brazen defiance of stakeholders' needs, is the main culprit of an unsustainable and irresponsible corporate environment. © 2016 Elsevier Ltd. Source

Ashrafizadeh S.N.,Iran University of Science and Technology | Ameri Ghasrodashti A.,Tarbiat Modares University
Chemical Engineering Research and Design | Year: 2011

Miscible gas injection is generally used as one of the most efficient methods in the enhanced oil recovery. Minimum miscibility pressure (MMP) is an important parameter in the miscible gas injection projects, since local displacement efficiency in the reservoir media is highly dependent on the MMP. Therefore, an appropriate estimation of MMP would bring significant economic benefits. This paper presents a comparative study on five representative equations of state (EoSs) for predicting MMP using Parachor model together with the criterion of zero interfacial tension (IFT) at the miscibility conditions. The predicted MMP values are compared with the experimental data obtained from the most reliable measurement technique, so called slim tube method. Such a prediction would enables us to judge the accuracy of the results obtained from different equations of state as well as the capability of Parachor model to calculate the MMP. The results of predictions obtained for five oil-gas systems in this study reveal reliable MMP values within 5% of accuracy. © 2010 The Institution of Chemical Engineers. Source

Dadras S.,Utah State University | Momeni H.R.,Tarbiat Modares University
Proceedings of the IEEE Conference on Decision and Control | Year: 2011

This paper investigates the problem of state estimation for a class of fractional order nonlinear systems with uncertainty, using sliding mode technique. In other words, the purpose of the problem is to develop a fractional order sliding mode observer. Through the fractional order extension of the Lyapunov stability criterion, the stability analysis of the error system is completed and it is showed that the observer design guarantees the convergence of the estimation error. Two illustrative examples are provided to approve the theoretical results. © 2011 IEEE. Source

Eskandari M.,Islamic Azad University at Tehran | Homaee M.,Tarbiat Modares University | Mahmodi S.,University of Tehran
Waste Management | Year: 2012

Landfill site selection is a complicated multi criteria land use planning that should convince all related stakeholders with different insights. This paper addresses an integrating approach for landfill siting based on conflicting opinions among environmental, economical and socio-cultural expertise. In order to gain optimized siting decision, the issue was investigated in different viewpoints. At first step based on opinion sampling and questionnaire results of 35 experts familiar with local situations, the national environmental legislations and international practices, 13 constraints and 15 factors were built in hierarchical structure. Factors divided into three environmental, economical and socio-cultural groups. In the next step, the GIS-database was developed based on the designated criteria. In the third stage, the criteria standardization and criteria weighting were accomplished. The relative importance weights of criteria and subcriteria were estimated, respectively, using analytical hierarchy process and rank ordering methods based on different experts opinions. Thereafter, by using simple additive weighting method, the suitability maps for landfill siting in Marvdasht, Iran, was evaluated in environmental, economical and socio-cultural visions. The importance of each group of criteria in its own vision was assigned to be higher than two other groups. In the fourth stage, the final suitability map was obtained after crossing three resulted maps in different visions and reported in five suitability classes for landfill construction. This map indicated that almost 1224. ha of the study area can be considered as best suitable class for landfill siting considering all visions. In the last stage, a comprehensive field visit was performed to verify the selected site obtained from the proposed model. This field inspection has confirmed the proposed integrating approach for the landfill siting. © 2012 Elsevier Ltd. Source

Aboutorabi L.,Payame Noor University | Morsali A.,Tarbiat Modares University
Inorganica Chimica Acta | Year: 2010

A new nano-sized lead(II) coordination polymer of maleic acid (H 2Mal), [Pb(u.7-Mal)]., (1), has been synthesized by sonochemical method and characterized by scanning electron microscopy, X-ray powder diffraction, elemental analyses and IR spectroscopy. The compound 1 was structurally characterized by single-crystal X-ray diffraction. Thermal stability of nano and bulk samples of compound 1 were studied and compared with each other. After calcination of nano-sized compound 1 at 600 ̈C, pure phase microsized lead(II) oxide has been produced. © 2010 Elsevier B.V. All rights reserved. Source

Shetabivash H.,Tarbiat Modares University
Energy and Buildings | Year: 2015

A three dimensional computational fluid dynamics (CFD) model is presented to investigate effective parameters on cross ventilation and air flow pattern inside a building. The numerical methodology is based on the finite volume numerical solution of the Navier-Stokes equations, using the CFD commercial code FLUENT. Numerical results are validated with available experimental data. Different opening position and shape configurations are used to investigate effect of position and shape of openings on the flow pattern inside the building. It is shown that openings can determine behavior of flow stream inside the building and designers can use them to increase natural ventilation efficiency of the building and control the recirculation zones which are formed in different rooms. © 2015 Published by Elsevier B.V. Source

Ghambarian M.,Iranian Research and Development Center for Chemical Industries | Yamini Y.,Tarbiat Modares University | Esrafili A.,Tehran University of Medical Sciences
Microchimica Acta | Year: 2013

Microextraction of organic or inorganic analytes using solidified floating drops of organic solvents is a fairly new method that is simple and rapid, and requires only small quantities of solvents and reagents. This review (with 109 references) covers published work up to Sep. 2012, and describes how the method was combined with analytical techniques such as GC, HPLC, ICP-OES and electrothermal atomic absorption spectrometry. We discuss basic principles and the main parameters that affect the extraction efficiency, and give specific applications of the technique. © 2013 Springer-Verlag Wien. Source

Kazemi Najafi S.,Tarbiat Modares University
Waste Management | Year: 2013

The use of recycled and waste thermoplastics has been recently considered for producing wood plastic composites (WPCs). They have great potential for WPCs manufacturing according to results of some limited researches. This paper presents a detailed review about some essential properties of waste and recycled plastics, important for WPCs production, and of research published on the effect of recycled plastics on the physical and mechanical properties of WPCs. © 2013 Elsevier Ltd. Source

Yang J.,Iowa State University | Ghobadian S.,Tarbiat Modares University | Goodrich P.J.,Iowa State University | Montazami R.,Iowa State University | Hashemi N.,Iowa State University
Physical Chemistry Chemical Physics | Year: 2013

This paper discusses the fundamentals and developments of miniaturized fuel cells, both biological and electrochemical. An overview of microfluidic fuel cells, miniaturized microbial fuel cells, enzymatic biofuel cells, and implanted biofuel cells in an attempt to provide green energy and to power implanted microdevices is provided. Also, the challenges and applications of each type of fuel cell are discussed in detail. Most recent developments in fuel cell technologies such as novel catalysts, compact designs, and fabrication methods are reviewed. © the Owner Societies 2013. Source

Shirani A.,Islamic Azad University at Ahvaz | Momenzadeh M.,Islamic Azad University at Ahvaz | Sanjabi S.,Tarbiat Modares University
Surface and Coatings Technology | Year: 2012

The influence of sodium dodecyl sulfate (SDS) as anionic surfactant and cetyltrimethyl ammonium bromide (CTAB) as cationic surfactant on the morphology, composition, and texture and corrosion behavior of electrodeposited Co-TiO 2 coatings was investigated. The polarization test revealed that the coatings deposited from SDS containing solution formed passive layer in low current densities and high positive voltages than coatings deposited in CTAB containing solution. The corrosion resistance of deposited coatings from SDS containing solution was improved in NaOH and H 2SO 4 solutions than CTAB one. The performed impedance test results in both corrosive media were compatible with the results of polarization test. The coatings deposited with CTAB had grains structure of 62nm whilst SDS ones showed finer grains around 45nm, which it was evaluated by XRD analysis and chronoamperometry extrapolation. © 2011 Elsevier B.V. Source

Fazilat H.,Islamic Azad University at Tehran | Akhlaghi S.,Islamic Azad University at Tehran | Shiri M.E.,Iran University of Science and Technology | Sharif A.,Tarbiat Modares University
Polymer | Year: 2012

A multi-structured architecture of artificial intelligence techniques including artificial neural network (ANN), adaptive-neuro-fuzzy-interference system (ANFIS) and radial basis function (RBF) were developed to predict thermal degradation kinetics (TDK) of nylon6 (NY6)/feather keratin (FK) blend films. By simultaneous implementation of back-propagation ANN and feed-forward ANFIS modeling on the experimental data obtained from thermogravimetric analysis (TGA) method, thermal degradation behavior of various compositions of NY6/FK blends was successfully predicted with minimum mean square errors (MSE). RBF networks were then trained on the TGA data at one heating rate for predicting analogs information at different heating rates, providing sufficient feed for TDK modeling. According to the comparison made between experimental and predicted kinetic parameters of thermal degradation process calculated from Friedman and Kissinger methods, the proposed prediction effort could effectively contribute to the estimation of precise activation energy (E a) and reaction order (n) values with least amount of experimental work and most accuracy. © 2012 Elsevier Ltd. All rights reserved. Source

Gazor S.,Queens University | Alihemmati R.,Tarbiat Modares University
IEEE Transactions on Wireless Communications | Year: 2012

The performance of Orthogonal Frequency Division Multiplexing (OFDM) systems is highly impacted by clipping distortions caused by non-linear amplifiers. One approach known as Tone Reservation (TR) method is to allocate/use a small number of sub-carriers to generate more suited signals and reduce the impact of these non-linear distortions. Traditionally, existing TR algorithms attempt to minimize the Peak-to-Average Power Ratio (PAPR). In this paper, we show that maximization of the Signal-to-Distortion Ratio (SDR) is a better criterion which achieves a better symbol error rate performance. Our results reveal that the proposed approach outperforms in terms of error probability rate for the same transmit power and same order of computational cost. Interestingly, the PAPR value for the proposed algorithm is not better than the state of the art algorithm in [1] which directly optimizes the PAPR. © 2012 IEEE. Source

Mohajjel M.,Tarbiat Modares University | Fergusson C.L.,University of Wollongong
International Geology Review | Year: 2014

The Zagros Mountains of Iran formed by continental collision from closure of the Neo-Tethyan Ocean. The Zagros Orogen underlying the mountain range reflects a much longer history with the Pan-African basement and Phanerozoic successions. New mapping, radiometric ages, and stratigraphic analyses have enabled advances in our understanding of the Jurassic to Cenozoic tectonic history. The northwestern Zagros Orogen consists of three belts: (1) the Zagros Fold and Thrust Belt, divided into the outer Zagros Simply Folded Belt and the inner High Zagros Belt; (2) the Zagros Suture Zone including radiolarite, ophiolite, and Bisotun limestone thrust sheets; and (3) the Sanandaj-Sirjan Zone, which contains abundant metamorphic rocks. Late Cretaceous ophiolites of the Kermanshah region are part of the outer ophiolite belt of the Zagros Orogen and have formed in passive margin and supra-subduction zone settings. Major events include early Mesozoic rifting, Jurassic subduction followed by a more cryptic interval of subduction in the Cretaceous, multiple ophiolite emplacement on the Arabian margin in the Late Cretaceous to Eocene, and collision of central Iran and the Arabian margin in the Oligocene with final closure of the shallow Tethyan seaway in the mid-Miocene. A Middle to Late Jurassic plutonic belt, the Qorveh-Aligodarz Plutonic Belt, formed a magmatic arc with subdued topography related to a moderately NE-dipping subduction zone under the Sanandaj-Sirjan Zone. An Early Cretaceous unconformity reflects limited uplift followed by widespread marine deposition with intercalated volcanic rocks in the Sanandaj region. Subduction continued with a low-lying arc that underwent trenchward advance. In the Late Cretaceous to Oligocene interval, the Neo-Tethyan Ocean closed with ophiolite obduction over the Arabian Peninsula margin and major shortening affected the Sanandaj-Sirjan Zone with uplift and plutonism. Much of the forearc of the Jurassic to Cretaceous arc system has been lost by tectonic erosion along a low-angle Eocene subduction zone prior to collision. Flattening of the subducting slab in the Late Cretaceous and Palaeogene explains the inland retreat of the arc to central Iran. Continental collision initiated in the Oligocene but the Tethyan seaway remained open until the mid-Miocene. © 2013 Taylor and Francis. Source

Abdoli A.,Tarbiat Modares University
Medical Hypotheses | Year: 2016

Salt is a major mineral element that plays fundamental roles in health and disease. Excessive salt intake is a major cause of hypertension, cardiovascular disease and stroke. Miscarriage and preeclampsia are the most common pregnancy complications with multiple etiological factors, including inflammatory and autoimmune conditions. More recently, different studies indicated that excessive salt intake is involved in the development of inflammatory processes through induction of T helper-17 pathway and their inflammatory cytokines. On the other hand, several studies indicated the pivotal role of inflammation in the etiology of miscarriage, preeclampsia and adverse pregnancy outcome. Here, it is hypothesized that excessive salt intake around the time of conception or during pregnancy can trigger inflammatory processes, which consequently associated with increased risk of miscarriage, preeclampsia or adverse pregnancy outcome. Thus, this hypothesis suggests that low salt intake around the time of conception or during pregnancy can decrease the risk of miscarriage or adverse pregnancy outcome. This hypothesis also offers new insights about the role of salt in the etiology of miscarriage and preeclampsia. © 2016 Elsevier Ltd. Source

Agheli L.,Tarbiat Modares University
International Journal of Energy Economics and Policy | Year: 2015

This paper estimates per capita demand for diesel by agricultural sector in Iran using auto-regressive distributed lags method over 1973-2012. The findings indicate that the demand for diesel is relatively inelastic in response to changes in its price, electricity acts as substitute input for diesel, diesel is a necessary input in agriculture, and mechanization index, despite having expected positive sign, fails to explain variations in diesel use. In addition, there is a long-run relationship among variables. According to error correction model, the speed of adjustment in short-run distortions towards long-run equilibrium is moderate. The findings show that government policy on cutting energy subsidies is not enough for reducing diesel consumption in Iranian agricultural sector. Thus, non-price measures such as innovations in inter-fuel substitution technologies and applying efficient machineries are recommended to manage energy uses in agriculture. © 2015, Econjournals. All right resurved. Source

Andervazh M.-R.,Islamic Azad University at Tehran | Olamaei J.,Islamic Azad University at Tehran | Haghifam M.-R.,Tarbiat Modares University
IET Generation, Transmission and Distribution | Year: 2013

This study proposes a Pareto-based multi-objective distribution network reconfiguration (DNRC) method using discrete particle swarm optimisation algorithm. The objectives are minimisation of power loss, the number of switching operations and deviations of bus voltages from their rated values subjected to system constraints. Probabilistic heuristics and graph theory techniques are employed to improve the stochastic random search of the algorithm self-adaptively during the optimisation process. An external archive is used to store non-dominated solutions. The archive is updated iteratively based on the Pareto-dominance concept to guide the search towards the Pareto optimal set. The method is implemented on the IEEE 33-bus and IEEE 70-bus radial distribution systems, simulations are carried out and results are compared with other available approaches in the literature. To assess the performance of the proposed method, a quantitative performance assessment is done using several performance metrics. The obtained results demonstrate the effectiveness of the proposed method in solving multi-objective DNRC problems by obtaining a Pareto front with great diversity, high quality and proper distribution of non-dominated solutions in the objective space. © The Institution of Engineering and Technology 2013. Source

Rahmani-andebili M.,Tarbiat Modares University
IET Generation, Transmission and Distribution | Year: 2013

By increasing the spinning reserve capacity, reliability of the power system is improved, however, total cost is increased. Therefore to supply the spinning reserve of power system, a compromise between reliability and cost should be considered. In this study, by considering the value of lost load for each important customer, the spinning reserve capacity is determined based on minimisation of total cost of problem. In addition, to supply the spinning reserve of power system, a new market player called plug-in electric vehicles (PEVs) aggregator is proposed. In this base, the aggregator's selfscheduling problem for participating in spinning reserve market is modelled using an agent-based model and behaviour of the PEVs fleet is modelled from the aggregator's point of view. To improve the accuracy of results, the market players are considered as price makers and their offers to the market are modelled using a dynamic game theory simulation. The numerical results show that the presence of PEVs aggregator in spinning reserve market has desired impacts on power system reliability and total cost of system. © The Institution of Engineering and Technology 2013. Source

Shariatmadari F.,Tarbiat Modares University
World's Poultry Science Journal | Year: 2012

Until recent years, planning broiler feeding appeared an easy task to implement. However, there are about ten feeding programs around today. 'In-ovo feeding', 'hatchery or early feeding', 'pre-starter diet', 'three fixed NRC phases' 'multi-phased feeding', 'feeding time period', 'sequential feeding', 'choice feeding', 'restriction feeding', 'nutrient (mineral and vitamins) withdrawal', 'replacer finisher feed' (withdrawal supplement feed) and/or pre slaughter feed (removal) and 'enrichment feed' are the main feeding programs that attract many involved in the poultry industry. With so many different feeding programs, an effective feeding plan might seem a complicated issue and difficult to conduct. The effectiveness and shortcomings of such programs are discussed so that a broiler feeding plan can be chosen more effectively. © World's Poultry Science Association 2012. Source

Haghighi Mood S.,Islamic Azad University at Tehran | Hossein Golfeshan A.,Islamic Azad University at Tehran | Tabatabaei M.,Agricultural Biotechnology Research Institute of Iran | Salehi Jouzani G.,Agricultural Biotechnology Research Institute of Iran | And 4 more authors.
Renewable and Sustainable Energy Reviews | Year: 2013

Pretreatment technologies are aimed to increase enzyme accessibility to biomass and yields of fermentable sugars. In general, pretreatment methods fall into four different categories including physical, chemical, physico-chemical, and biological. This paper comprehensively reviews the lignocellulosic wastes to bioethanol process with a focus on pretreatment methods, their mechanisms, advantages and disadvantages as well as the combinations of different pretreatment technologies. Moreover, the new advances in plant "omics" and genetic engineering approaches to increase cellulose composition, reduce cellulose crystallinity, produce hydrolases and protein modules disrupting plant cell wall substrates, and modify lignin structure in plants have also been expansively presented. © 2013 Published by Elsevier Ltd. All rights reserved. Source

Rahmani-andebili M.,Tarbiat Modares University
IET Generation, Transmission and Distribution | Year: 2013

Demand-side management (DSM) has been introduced as the first choice in all energy policy decisions because of its potential benefits at operation and economic levels. After restructuring, the DSM programs were expanded to include demand response programs (DRPs). In this study, in order to solve generation scheduling problem, demand-side resources (DSRs) are linked to supply-side resources (SSRs) and the DRPs are intelligently implemented by ISO with the aim of minimising the total cost of unit commitment (UC) problem (UCDSR). In order to investigate the effects of connection of DSRs to the SSRs on the UCDSR problem, some of the most important voluntary DRPs are considered and also in order to investigate the effect of responsive loads models on the UCDSR problem, linear and non-linear models of responsive loads such as potential, exponential, and logarithmic models are considered and implemented. In this study, the economic models of responsive loads are derived based on price elasticity of demand and consumers' surplus function. The proposed method is intelligently applied on a ten-unit system to determine the best scheme for implementing DRPs and commitment status of units. It is shown that obtaining the minimum cost for system using an unsuitable scheme of DRPs or unreal model for responsive loads is not possible. ©The Institution of Engineering and Technology 2013. Source

Alibeigloo A.,Tarbiat Modares University
Journal of Thermal Stresses | Year: 2012

Three-dimensional analysis of a functionally graded (FG) solid and an annular circular plate subjected to thermo-mechanical load with various boundary conditions are carried out in this paper. At first, the temperature gradient can be derived by solving the heat conduction equation exactly and then by applying the differential quadrature method (DQM) along the radial direction and by using the state-space method in the thickness direction to the governing state equations results in a system of first-order differential equations, which can be solved analytically. The thermo-elastic constants of the plate are assumed to vary exponentially through the thickness, and the Poisson ratio is held to be constant. To verify the accuracy of the present work, a comparison is made with previously published results. The effects of temperature change, mechanical load, gradient index, edges conditions and thickness to radial length ratio on the behavior of the plate are examined. © 2012 Copyright Taylor and Francis Group, LLC. Source

Imaanpur A.,Tarbiat Modares University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

We construct a U(1) bundle over N(1, 1), usually considered as an SO(3) bundle on CP2, and show that type IIB supergravity can be consistently compactified over it. With the five form flux turned on, there is a solution for which the metric becomes Einstein. We further turn on 3-form fluxes and show that there is a one parameter family of solutions. In particular, there is a limiting solution of large 3-form fluxes for which two U(1) fiber directions of the metric shrink to zero size. We also discuss compactifications over N(1, 1) to AdS3. All solutions turn out to be non-supersymmetric. © 2014 The Author. Source

Mirzaei M.,Tarbiat Modares University
International Journal of Mechanical Sciences | Year: 2012

This paper presents a set of analytical solutions for the vibrational behavior of thin tubes under sequences of internal moving pressures. Such analyses are applicable to a number of theoretical and practical problems, like transient dynamic response of arteries due to pulsatory blood flow, transient deformations of gas pipelines due to pressure fluctuations, or the vibrational response of pulse detonation engines (PDE). However, the presented solutions are tailored for successive applications of specific loading profiles that represent gaseous detonations. The solutions are compared with the available experimental data and complementary finite element simulations. Representative analyses are carried out for an experimental detonation tube under loading spectra traveling with different time delays. It is shown that the resulting vibrational spectra can be highly affected by the frequency of the sequential loadings and high dynamic amplification factors can exist even at non-critical speeds. It is also shown that application of sequential moving pressures with proper loading frequencies can substantially reduce the structural vibration. © 2012 Elsevier Ltd. All rights reserved. Source

Beiranvand R.,Tarbiat Modares University
Review of Scientific Instruments | Year: 2014

In this paper, effects of the assembly misalignments and the manufacturing mismatches on the magnetic field uniformity of a practical tri-axial Helmholtz coils system have been modeled mathematically. These undesired effects regularly occur in any practical tri-axial Helmholtz coils system. To confirm the mathematical calculations, a tri-axial Helmholtz coils system has been constructed and the uniformity of its magnetic field has been measured under different conditions. The experimental results are in good agreement with the mathematical analyses. © 2014 AIP Publishing LLC. Source

Mehrjoo M.,Islamic Azad University at Tehran | Khaji N.,Tarbiat Modares University | Ghafory-Ashtiany M.,International Institute of Earthquake Engineering and Seismology
Applied Soft Computing Journal | Year: 2013

In this paper, a crack identification approach is presented for detecting crack depth and location in beamlike structures. For this purpose, a new beam element with a single transverse edge crack, in arbitrary position of beam element with any depth, is developed. The crack is not physically modeled within the element, but its effect on the local flexibility of the element is considered by the modification of the element stiffness as a function of crack's depth and position. The development is based on a simplified model, where each crack is substituted by a corresponding linear rotational spring, connecting two adjacent elastic parts. The localized spring may be represented based on linear fracture mechanics theory. The components of the stiffness matrix for the cracked element are derived using the conjugate beam concept and Betti's theorem, and finally represented in closed-form expressions. The proposed beam element is efficiently employed for solving forward problem (i.e., to gain accurate natural frequencies of beam-like structures knowing the cracks' characteristics). To validate the proposed element, results obtained by new element are compared with two-dimensional (2D) finite element results as well as available experimental measurements. Moreover, by knowing the natural frequencies, an inverse problem is established in which the cracks location and depth are identified. In the inverse approach, an optimization problem based on the new beam element and genetic algorithms (GAs) is solved to search the solution. The proposed approach is verified through various examples on cracked beams with different damage scenarios. It is shown that the present algorithm is able to identify various crack configurations in a cracked beam. © 2012 Elsevier B.V. All rights reserved. Source

Allameh A.,Tarbiat Modares University | Kazemnejad S.,Guilan University
Clinical Biochemistry | Year: 2012

There are several issues to be considered to reduce the risk of rejection and minimize side effects associated with liver cell transplantation in chronic liver diseases. The source and the condition of stem cell proliferation and differentiation ex vivo and the transplantation protocols are important safety considerations for cell based therapy. The biochemical and molecular markers are important tools for safety evaluation of different processes of cell expansion and transplantation. Studies show that hepatocytes differentiated from adult and embryonic stem cells exhibit biochemical and metabolic properties resembling mature hepatocytes. Therefore these assays can help to assess the biological and metabolic performance of hepatocytes and progenitor stem cells. The assays also help in testing the contribution of transplanted hepatocytes in improving the repair and function of damaged liver in the recipient.Here we review the biochemical and metabolic markers, which are implicated in evaluation of safety issues of stem cells used for therapeutic purposes in chronic liver diseases and regeneration of damaged liver. We also highlight application of biochemical tests for assessment of liver cell transplantation. © 2012 The Canadian Society of Clinical Chemists. Source

Ghobadian B.,Tarbiat Modares University
Renewable and Sustainable Energy Reviews | Year: 2012

Iran's diversity of terrain and climate enables cultivation of a variety of energy crops suitable for liquid biofuels production. In Iran, the easily and readily available biofuel feedstock today for production of bioethanol is molasses from sugar cane and sugar beet. There is also about 17.86 million tons of crops waste from which nearly 5 billion liters of bioethanol could be produced annually. This amount of bioethanol is sufficient to carry out E10 for spark ignition engine vehicles in Iran by 2026. There is also enormous potential for cultivation of energy plants such as cellulosic materials and algae. Iran has 7%of its area covered with forest products which are suitable sources for liquid biofuels such bioethanol and biodiesel. Iran also has a long tradition of fishing in Caspian Sea and Persian Gulf with about 3200 km coastline and on inland rivers. The produced fish oil and other plant oils such as palm tree, jatropha, castor plant and algae are suitable biodiesel feedstock. Out of 1.5 million tons of edible cooking oil consumed in Iran annually, about 20% of it can be considered as waste, which is suitable biodiesel feedstock.This quantity along with the other possible potential feedstock are favorable sources to carry out B10 step by step until 2026. © 2012 Elsevier Ltd. All rights reserved. Source

Modarres M.,University of Tehran | Younesizadeh Y.,Tarbiat Modares University
Physical Review C - Nuclear Physics | Year: 2012

In this work, the two-nucleon spectral functions (TNSFs) are defined in terms of the state- and the density-dependent correlation functions in the framework of the lowest-order constrained variational (LOCV) method to calculate the TNSF of the 16O nucleus in the 16O(e,e ′NN)14C reaction. The Reid soft-core (Reid68) and the Av 18 potentials are used as the internucleon interactions. Since, the short-range correlation effects are imposed on the wave functions for the individual channels (e.g., the 1S 0 and 3P J channels); therefore, the defect wave functions are obtained for various channels such that the high relative momenta (p>4fm -1) are ignored. The resulting TNSFs for the 16O nucleus are compared with those of the dressed random phase approximation (DRPA) calculations of Geurts and the experimental predictions, especially those of Onderwater, (NIKHEF group), where reasonable agreement is found. It is shown that the optimized state-dependent defect wave functions have substantial effects on the TNSF and it is not justified to use the simplified parametrized two-body correlation functions in all of the channels. In agreement with the experimental data of Onderwater, the knockout of a 1S 0 pair proton dominates the above reaction cross section. Finally, it is demonstrated that the 0 + and 2 + peaks, which are expected to be observed in the above reaction cross section, are moved to the lower momenta of out-going protons when the state-dependent correlation functions are imposed. © 2012 American Physical Society. Source

Based on three-dimensional theory of elasticity, bending behavior of functionally graded carbon nanotube reinforced composite (FG-CNTRC) plate embedded in thin piezoelectric layers subjected to mechanical uniform load with simply supported boundary conditions is investigated. By using Fourier series expansion along the longitudinal and latitudinal directions and state space technique across the thickness direction closed form solution is derived. Accuracy and convergence of the presents approach, is validated by comparing the numerical results with the published numerical results in the literature. In addition, the effects of volume fraction of CNT, two case of FG-CNTRC, piezoelectric layer thickness, length to thickness ration and modes number on the static behavior of the hybrid plate are also examined. © 2012 Elsevier Ltd. Source

Neyshabur B.,Sharif University of Technology | Khadem A.,Sharif University of Technology | Hashemifar S.,University of Tehran | Arab S.S.,Tarbiat Modares University | Arab S.S.,Institute for Research in Fundamental Sciences
Bioinformatics | Year: 2013

Motivation: The interactions among proteins and the resulting networks of such interactions have a central role in cell biology. Aligning these networks gives us important information, such as conserved complexes and evolutionary relationships. Although there have been several publications on the global alignment of protein networks; however, none of proposed methods are able to produce a highly conserved and meaningful alignment. Moreover, time complexity of current algorithms makes them impossible to use for multiple alignment of several large networks together.Results: We present a novel algorithm for the global alignment of protein-protein interaction networks. It uses a greedy method, based on the alignment scoring matrix, which is derived from both biological and topological information of input networks to find the best global network alignment. NETAL outperforms other global alignment methods in terms of several measurements, such as Edge Correctness, Largest Common Connected Subgraphs and the number of common Gene Ontology terms between aligned proteins. As the running time of NETAL is much less than other available methods, NETAL can be easily expanded to multiple alignment algorithm. Furthermore, NETAL overpowers all other existing algorithms in term of performance so that the short running time of NETAL allowed us to implement it as the first server for global alignment of protein-protein interaction networks. © The Author 2013. Source

Asosheh A.,Tarbiat Modares University | Nalchigar S.,University of Tehran | Jamporazmey M.,University of Tehran
Expert Systems with Applications | Year: 2010

Information technology (IT) is a tool crucial for enterprises to achieve a competitive advantage and organizational innovation. A critical aspect of IT management is the decision whereby the best set of IT projects is selected from many competing proposals. The optimal selection process is a significant strategic resource allocation decision that can engage an organization in substantial long-term commitments. However, making such decisions is difficult because there are lots of quantitative and qualitative factors to be considered in evaluation process. This paper has two main contributions. Firstly, it combines two well-established managerial methodologies, balanced scorecard (BSC) and data envelopment analysis (DEA), and proposes a new approach for IT project selection. This approach uses BSC as a comprehensive framework for defining IT projects evaluation criteria and uses DEA as a nonparametric technique for ranking IT projects. Secondly, this paper introduces a new integrated DEA model which identifies most efficient IT project by considering cardinal and ordinal data. Applicability of proposed approach is illustrated by using real world data of Iran Ministry of Science, Research and Technology. © 2010 Elsevier Ltd. All rights reserved. Source

Esrafili M.D.,Islamic Azad University at Maragheh | Hadipour N.L.,Tarbiat Modares University
Molecular Physics | Year: 2011

A theoretical study was performed to examine intermolecular halogen bond properties in one-dimensional NCX chains (X=Cl and Br). Geometries, binding energies, and n N → σ* c-x charge-transfer of linear (NCCl) 2-10 and (NCBr) 2-10 chains were investigated by means of second-order Møller-Plesset perturbation theory (MP2) and DFT methods. All MP2, B3LYP and M06/aug-cc-pVTZ results indicate that the magnitudes of the interaction energies increase with increasing halogen size. Considering MP2/aug-cc-pVTZ results, it can be seen that the (NCBr) 10 cluster is bound 12.72kcal/mol more strongly than (NCCl) 10. The n-dependent trend of n N → σ* c-xcharge-transfer is reasonably correlated with cooperative effects in halogen bond energies. According to the quantum theory of atoms in molecules, the capability of the (NCX) 2-10 clusters for electron localization, at the C-X⋯N bond critical point (BCPs), depends on the cluster size and thereby leads to cooperative changes in the C-X⋯N strength, and n N → σ* c-x charge-transfer. It is also revealed that for all intermolecular C-X⋯N interactions, total electronic energy densities are all greater than zero, suggesting that the interactions are significantly electrostatic in nature. © 2011 Taylor and Francis Group, LLC. Source

Kent J.T.,University of Leeds | Mohammadzadeh M.,Tarbiat Modares University | Mosammam A.M.,University of Zanjan
Biometrika | Year: 2011

Gneiting (2002) proposed a nonseparable covariance model for spatial-temporal data. In the present paper we show that in certain circumstances his model possesses a counterintuitive dimple. In some cases, the magnitude of the dimple can be nontrivial. © 2011 Biometrika Trust. Source

Light olefins are one of the main raw materials for the petrochemical industry. They are mainly produced by steam cracking of hydrocarbons from ethane to gasoil. The pyrolysis takes place in the tubular reactors, inside the firebox of the furnace, at high temperature, low pressure and a very short residence time. This is the only available industrial process exists for the production of olefins yet although there are other processes such as catalytic cracking for the production of such materials. This paper reviews the main research works done on the process in the literature in the last five decades. Three sections of the furnace and tubular reactors which are fixed inside the furnace have been described in detail. A mathematical model is presented for the simulation of the firebox and the reactor. Some of the main experimental laboratory setup systems in the world have been reviewed and parts of the results are presented and discussed. Finally, a few computer software packages for the simulation and online optimization of thermal cracking furnaces are presented. © 2014 Elsevier Ltd. Source

Pakravan N.,Kermanshah University of Medical Sciences | Hassan Z.M.,Tarbiat Modares University
Cell Stress and Chaperones | Year: 2011

It has been frequently reported that gp96 acts as a strong biologic adjuvant. Some studies have even investigated adjuvant activity of the gp96 C- or N-terminal domain. The controversy surrounding adjuvant activity of gp96 terminal domains prompted us to compare adjuvant activity of gp96 C- or N-terminal domain toward Her2/neu, as DNA vaccine in a Her2/neu-positive breast cancer model. To do so, mice were immunized with DNA vaccine consisting of transmembrane and extracellular domain (TM + ECD) of rat Her2/neu alone or fused to N- or C-terminal domain of gp96. Treatment with Her2/neu fused to Nterminal domain of gp96 resulted in tumor progression, compared to the groups vaccinated with pCT/Her2 or pHer2. Immunological examination revealed that treatment with Her2/neu fused to N-terminal domain of gp96 led to significantly lower survival rates, higher interferon-γ secretion, and induced infiltration of CD4 +/CD8+ cells to the tumor site. However, it could not induce cytotoxic T lymphocyte activity, did not decrease regulatory T cell percentage at the tumor site, and eventually led to tumor progression. Our results reveal that gp96 N-terminal domain does not have adjuvant activity toward Her2/neu. It is also proposed that adjuvant activity and the resultant immune response of gp96 terminal domains may be directed by the antigen applied. © 2011 Cell Stress Society International. Source

Alibeigloo A.,Tarbiat Modares University | Liew K.M.,City University of Hong Kong
Composite Structures | Year: 2013

Based on three-dimensional theory of elasticity, bending behavior of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) rectangular plate with simply supported edges subjected to thermo-mechanical loads is examined. By using Fourier series expansion along the in plane directions and state space technique across the thickness direction for the entities exact solution for bending characteristic of plate is derived. Accuracy of the presents approach is validated by comparing the numerical results with the available published results in the literature. Investigation on the static behavior of the plates is further carried out by considering the effects of volume fraction of carbon nanotube, uniform distribution and functionally graded distribution of carbon nanotube, aspect ratio and length to thickness ratio. © 2013 Elsevier Ltd. Source

Faezi S.,Tarbiat Modares University
Burns : journal of the International Society for Burn Injuries | Year: 2011

This study was aimed to investigate whether anti-recombinant flagellin type A (anti r-fla-A) immunoglobulin G (IgG) provides protection in a mouse burn model of infection, and to determine the role of anti r-fla-A IgG as an opsonin and motility inhibitor in local and systemic infections. Following the preparation of r-flagellin type A, rabbit polyclonal IgG was prepared. Specificity of anti r-flagellin for r-flagellin was evaluated by immunoblot analysis. After burn and challenge, mortality rate was screened in the mice treated with anti r-fla-A IgG. The ability of antiserum to promote phagocytosis of bacteria was assessed by the opsonophagocytosis testing. Functional activity of anti r-fla-A IgG was assessed in vitro by motility inhibition assay. Bacterial quantity in skin and internal organs was evaluated to study systemic infection. In vivo administration of anti r-fla-A IgG resulted in a significant improvement in survival in mice infected by a homologous strain of Pseudomonas aeruginosa from 16.6% to 75% compared with the control IgG. By contrast, this rate was 33.3% in the mice infected by the heterologous strain, PAO1 (type B flagellated strain). Protection was improved by giving a second treatment of r-flagellin antisera at 24-h post-burn and infection. Furthermore, anti r-fla-A IgG enhanced considerably the phagocytosis of the homologous strain but it was slight in the heterologous strain. The antiserum against r-flagellin type A was able to inhibit the motility of the PAK strain (type A flagellated strain), but slight inhibition was observed against PAO1. Meanwhile, anti r-fla-A IgG inhibited the systemic spread of PAK strain from the site of infection to internal organs. In this study, passive immunisation with anti r-fla-A IgG was active against a homologous strain of infecting P. aeruginosa, but lost most of its efficiency against a heterologous strain. Therefore, passive treatment with anti r-fla-A IgG might protect burned mice against local and systemic infection of P. aeruginosa. Copyright © 2010 Elsevier Ltd and ISBI. All rights reserved. Source

Rad A.B.,Islamic Azad University at Karaj | Alibeigloo A.,Tarbiat Modares University
Mechanics of Advanced Materials and Structures | Year: 2013

The effects of two-parameter linear elastic foundations on axisymmetric response of two directionally functionally graded circular plates are investigated by using a differential quadrature method. The state equations are derived based on 3D theory of elasticity, and assuming the modulus of elasticity varies continuously throughout the thickness and radius directions in the form of an exponential function, and the Poisson's ratio is constant. The stresses and displacements distribution are obtained by solving these state equations. The influences of gradient indices, thickness to radius ratio, foundation stiffness, and edge supports on the static behavior of a plate are studied in the numerical examples. © 2013 Copyright Taylor and Francis Group, LLC. Source

Babanzadeh S.,Iran Polymer And Petrochemical Institute | Mehdipour-Ataei S.,Iran Polymer And Petrochemical Institute | Mahjoub A.R.,Tarbiat Modares University
Designed Monomers and Polymers | Year: 2013

New polyimide-silica (PI-SiO2) nanohybrids were prepared by the reaction of bis(5-amino-1-naphthoxy) diphenylsilane (5-APS) with commercially available 4,4′-(Hexafluoroisopropylidene) diphthalic anhydride (6-FDA) in the presence of 3-aminopropyl triethoxysilane as a coupling agent and tetraethylorthosilicate (TEOS) as precursor of inorganic network. Hybrid thin films with 5-50 wt.% silica content were synthesized. The prepared PI-SiO 2 films were characterized by Fourier transform infrared spectroscopy and energy dispersive X-ray spectroscopy. The morphology and crystallinity of these hybrid systems were investigated by transmission electron microscopy and XRD analysis. Thermal properties of the nanohybrids were evaluated by thermogravimetric analysis and dynamic mechanical thermal analysis techniques. The optical constants (n and k) and dielectric parameters (ε′ and ε″) were calculated from IR reflection spectra by employing the Kramers-Kronig dispersion relations. Under proper condition, the silica particle size was in the range of 50-70 nm for the prepared hybrids. The results showed that presence of silica severely modified the properties of samples. © 2012 Taylor & Francis. Source

Sadeqzadeh E.,Tarbiat Modares University
Journal of controlled release : official journal of the Controlled Release Society | Year: 2011

We provide evidence for combining a single domain antibody (nanobody)-based targeting approach with transcriptional targeting as a safe way to deliver lethal transgenes to MUC1 over-expressing cancer cells. From a nanobody immune library, we have isolated an anti-DF3/Mucin1 (MUC1) nanobody with high specificity for the MUC1 antigen, which is an aberrantly glycosylated glycoprotein over-expressed in tumours of epithelial origin. The anti-MUC1 nanobody was covalently linked to the distal end of poly(ethylene glycol)(3500) (PEG(3500)) in PEG(3500)-25kDa polyethylenimine (PEI) conjugates and the resultant macromolecular entity successfully condensed plasmids coding a transcriptionally targeted truncated-Bid (tBid) killer gene under the control of the cancer-specific MUC1 promoter. The engineered polyplexes exhibited favourable physicochemical characteristics for transfection and dramatically elevated the level of Bid/tBid expression in both MUC1 over-expressing caspase 3-deficient (MCF7 cells) and caspase 3-positive (T47D and SKBR3) tumour cell lines and, concomitantly, induced considerable cell death. Neither transgene expression nor cell death occurred when the MUC1 promoter was replaced with the CNS-specific synapsin I promoter. Since PEGylated PEI was only responsible for DNA compaction and played no significant role in direct transfection and cell killing, our attempts overcome previously reported PEI-mediated apoptotic and necrotic cell death, which is advantageous for future in vivo transcriptional targeting as this will minimize (or eliminate) non-targeted cell damage. Copyright © 2011 Elsevier B.V. All rights reserved. Source

Mohebby B.,Tarbiat Modares University | Militz H.,University of Gottingen
International Biodeterioration and Biodegradation | Year: 2010

Microscopic evaluation of microbial attack in the acetylated wood after a long term exposure to the field soil was the main concern of the current research. Stakes of wood were cut from beech, poplar and Scots pine wood and acetylated by using acetic anhydride to achieve different weight percent gains (WPGs). Afterwards, the stakes were exposed to the field soil for 350 weeks according to EN 252. Small specimens were cut from the stakes, sectioned and stained for microscopic studies. Small blocks were also prepared for scanning electron microscopy (SEM). Microscopic observations indicated that the soft rot was dominant rot fungi in the field soil and decayed the non-acetylated wood severely and attack also the moderately acetylated wood slowly. Bacteria were also in close association with the soft rot fungi to degrade the acetylated and the non-acetylated wood. In the moderately acetylated wood, white rot decay was at developing stage, while it was at initial stage at the highest WPGs. Microscopy revealed that the initial stage of the decay was begun at the highest WPGs and it was at developing stage of the decay in the moderately acetylated wood. The less development of the decay in the acetylated wood comparing the non-acetylated wood proved very good protection of the wood against the soil microorganisms due to the acetylation after 7 years period. Soft rot and white rot decays were observed in the non-acetylated and the acetylated wood at the same time. No brown rot decay was observed in those woods. Bacteria were seen in all wood types. The bacteria cooperated generally with the soft rot fungi to degrade the non-acetylated wood or limit themselves to pits at the higher degrees of the acetylation. © 2009 Elsevier Ltd. All rights reserved. Source

Abdi M.J.,Tarbiat Modares University | Giveki D.,Saarland University
Engineering Applications of Artificial Intelligence | Year: 2013

In this paper, we develop a diagnosis model based on particle swarm optimization (PSO), support vector machines (SVMs) and association rules (ARs) to diagnose erythemato-squamous diseases. The proposed model consists of two stages: first, AR is used to select the optimal feature subset from the original feature set; then a PSO based approach for parameter determination of SVM is developed to find the best parameters of kernel function (based on the fact that kernel parameter setting in the SVM training procedure significantly influences the classification accuracy, and PSO is a promising tool for global searching). Experimental results show that the proposed AR-PSO-SVM model achieves 98.91% classification accuracy using 24 features of the erythemato-squamous diseases dataset taken from UCI (University of California at Irvine) machine learning database. Therefore, we can conclude that our proposed method is very promising compared to the previously reported results. © 2012 Elsevier Ltd. All rights reserved. Source

Miri M.S.,University of Iowa | Mahloojifar A.,Tarbiat Modares University
IEEE Transactions on Biomedical Engineering | Year: 2011

Retinal images can be used in several applications, such as ocular fundus operations as well as human recognition. Also, they play important roles in detection of some diseases in early stages, such as diabetes, which can be performed by comparison of the states of retinal blood vessels. Intrinsic characteristics of retinal images make the blood vessel detection process difficult. Here, we proposed a new algorithm to detect the retinal blood vessels effectively. Due to the high ability of the curvelet transform in representing the edges, modification of curvelet transform coefficients to enhance the retinal image edges better prepares the image for the segmentation part. The directionality feature of the multistructure elements method makes it an effective tool in edge detection. Hence, morphology operators using multistructure elements are applied to the enhanced image in order to find the retinal image ridges. Afterward, morphological operators by reconstruction eliminate the ridges not belonging to the vessel tree while trying to preserve the thin vessels unchanged. In order to increase the efficiency of the morphological operators by reconstruction, they were applied using multistructure elements. A simple thresholding method along with connected components analysis (CCA) indicates the remained ridges belonging to vessels. In order to utilize CCA more efficiently, we locally applied the CCA and length filtering instead of considering the whole image. Experimental results on a known database, DRIVE, and achieving to more than 94% accuracy in about 50 s for blood vessel detection, proved that the blood vessels can be effectively detected by applying our method on the retinal images. © 2006 IEEE. Source

Alibeigloo A.,Tarbiat Modares University
Acta Mechanica | Year: 2011

Vibration analysis of a nano-plate, based on three-dimensional theory of elasticity, is studied employing non-local continuum mechanics. By using state-space method in the thickness direction and Fourier series in the in-plane directions, a closed form solution for the natural frequencies of a rectangular simply supported nano-plate is obtained. To verify the accuracy of the present approach, numerical results are compared with the results available in the literature. The effect of the non-local parameter, aspect ratio, thickness-to-length ratio and half-wave numbers in the frequency behavior is examined. © 2011 Springer-Verlag. Source

Tasnimi A.A.,Tarbiat Modares University | Mohebkhah A.,University of Malaayer
Engineering Structures | Year: 2011

This article deals with an experimental program to investigate the in-plane seismic behavior of steel frames with clay brick masonry infills having openings. Six large-scale, single-story, single-bay frame specimens were tested under in-plane cyclic loading applied at roof level. The infill panel specimens included masonry infills having central openings of various dimensions. The experimental results indicate that infill panels with and without openings can improve the seismic performance of steel frames and the amount of cumulative dissipated energy of the infill panels with openings, at ultimate state are almost identical. Furthermore, contrary to the literature, the results indicate that infilled frames with openings are not always more ductile than the ones with solid infill. It seems that the ductility of such frames depends on the failure mode of infill piers. This experimental investigation shows that infilled frames with openings experienced pier diagonal tension or toe crushing failure and have smaller ductility factors than those frames with solid infill. Furthermore, a simple analytical method is proposed to estimate the maximum shear capacity of masonry infilled steel frames with window and door openings. © 2010 Elsevier Ltd. Source

Navaie K.,Tarbiat Modares University
Telecommunication Systems | Year: 2011

A study on interference management schemes in wireless multi-user networks is presented. We analyze the interference management problem in cellular networks and show that interference management is an optimization problem, for which we propose a general formulation. Using this general formulations we show that different interference management approaches are either exact or approximated solutions to this optimization problem. For each radio resource management technique, we provide a general overview and discuss its relation vis-a-vie other interference management techniques. As a case study, we then apply the proposed general formulation on the interference management in OFDM wireless networks and show that it results in a joint transmit scheduling and dynamic sub-carrier and power allocation scheme. A polynomial-time heuristic algorithm is also proposed to solve the formulated optimization problem. The distinguishing feature of the proposed scheme is that it gives in one shot, the transmission scheduling, the sub-carriers assigned to each user, and the power allocated to each sub-carrier, based on a fair and efficient framework while satisfying the delay requirements of real-time users. © 2010 Springer Science+Business Media, LLC. Source

Imaanpur A.,Tarbiat Modares University
Journal of High Energy Physics | Year: 2016

We study D-instanton solutions in type IIB supergravity on AdS5 ×T1,1, which has a dual (Formula presented.) SU(N) × SU(N) super Yang-Mills theory. Apart from ordinary D(-1)-brane instantons, we discuss wrapped D1-branes over minimal 2-cycles and derive explicit solutions preserving half the supersymmetries. These solutions are identified with Yang-Mills instantons which are (anti)self-dual in both gauge group factors with instanton charge (k,k′). By examining the boundary behaviour of the solutions we discuss the coupling to the corresponding dual boundary operators, and identify their vacuum expectation values. We also discuss the boundary terms and compute the action for these solutions. © 2016, The Author(s). Source

Yavari M.H.,TU Berlin | Ahmadi V.,Tarbiat Modares University
IEEE Journal on Selected Topics in Quantum Electronics | Year: 2011

The important tradeoff between frequency bandwidth and single-mode behavior of multimode self-assembled InAs-GaAs quantum-dot (QD) laser by increasing temperature or homogeneous broadening is addressed. The effects of carrier dynamics on the frequency response of columnar-shaped self-assembled QD laser are analyzed. The phonon bottleneck problem is simulated. It is shown that to prevent the effect of phonon bottleneck on the frequency behavior, carrier relaxation lifetime must be less than a critical value about a few pico seconds, which is in agreement with the experimental results. Results show that carrier recombination in wetting layer has no important effect on the modulation response; however, carrier recombination inside dots degrades frequency response drastically. © 2011 IEEE. Source

Ghadikolaei H.M.,Iran University of Science and Technology | Tajik E.,Iran University of Science and Technology | Aghaei J.,Shiraz University of Technology | Charwand M.,Tarbiat Modares University
Applied Energy | Year: 2012

This paper proposes a new framework for the operation of distribution companies (discos) in the liberalized electricity market environment considering distributed generation (DG) units and carbon dioxide (CO2) emission penalty cost. The proposed short-term framework is a two-stage model. The first stage, namely day-ahead stage, deals with the activities of discos. This stage includes a optimization problem to minimize the costs of distribution company (operational and CO2 emission costs). The first stage is formulated as a mixed integer nonlinear programming (MINLP) framework using the Benders decomposition to determine the decisions of discos to buy power from grid, schedule the DG units and contract with interruptible loads (ILs). The results of the first stage are imposed as the boundary constraints in the second stage which deals with the activities of discos in an hour-ahead period. In the hour-ahead stage, the retailers determine the amount of purchased active and reactive power from the grid and the production of each DG unit in the energy and reserve market keeping in mind its day-ahead decision to maximize the desired short-term profit. Finally, the efficiency of the proposed framework is studied on a case study. © 2012 Elsevier Ltd. Source

Abbaspur R.,Tarbiat Modares University
Nuclear Physics B | Year: 2016

We investigate possible stable configurations of two arbitrary branes at general angles using the dynamics of DBI. +. WZ action. The analysis naturally reveals two types of solutions which we identify as the "marginal" and "non-marginal" configurations. We characterize possible configurations of a pair of identical or non-identical branes in either of these two classes by specifying their proper intersection rules and allowed intersection angles. We also perform a partial analysis of configurations with multiple angles of a system of asymptotically flat curved branes. © 2016 The Author. Source

Ghazinoory S.,Tarbiat Modares University | Esmail Zadeh A.,Bu - Ali Sina University | Kheirkhah A.S.,Bu - Ali Sina University
Information Sciences | Year: 2010

In this paper, we draw upon portfolio analysis to develop and implement a strategic decision making model. We consider the limitations and problems of classic portfolio analysis approach and resolve these problems by using fuzzy set theory. In the proposed method, both internal and external factors are evaluated in linguistic terms and in terms of fuzzy triangular numbers. The fuzzy numbers are fed into an industry attractiveness-business analysis matrix. The novelty of the proposed approach comes from the fact that fuzzy numbers are processed without using conventional methods, allowing for strategies to be ranked. © 2010 Elsevier Inc. All rights reserved. Source

Mahmoudi Y.,University of Cambridge | Karimi N.,University of Glasgow | Mazaheri K.,Tarbiat Modares University
International Journal of Heat and Mass Transfer | Year: 2014

Enhancement of forced convective heat transfer is analytically investigated in a channel partially filled with a porous medium under local thermal non-equilibrium (LTNE) condition. Thermally and hydrodynamically fully developed conditions are considered. The flow inside the porous material is modelled by the Darcy-Brinkman-Forchheimer equation. The thermal boundary conditions at the interface between the porous medium and the clear region are described by two different models. For each interface model exact solutions are developed for the solid and fluid temperature fields. The Nusselt number (Nu) associated with each interface model is derived in terms of the porous insert normalised thickness (S) and other pertinent parameters such as thermal conductivity ratio (k), Biot number (Bi), and Darcy number (Da). The differences between the two interface models in predicting the temperature fields of the solid and fluid phases and validity of the Local Thermal Equilibrium (LTE) assumption are examined. Subsequently, for each model the values of S, Bi, k and Da at which LTE holds are determined. Further, the maximum values of S up to that the two models predict LTE condition are found as a function of Bi, k and Da. For each model and for different pertinent parameters the optimum value of S, which maximises the Nu number, is then found. The results show that, in general, the obtained Nu numbers can be strongly dependent upon the applied interface model. For large values of k and Bi, there are significant disparities between the Nu numbers predicted by the two models. Nonetheless, for most values of k and Bi, and under different values of Da numbers both models predict similar trends of variation of Nu number versus S. The Nu number and pressure drop ratio are then used to determine the Heat Transfer Performance (HTP). It is found that for S < 0.9, HTP is independent of Da number and the model used at the porous-fluid interface. For S > 0.9, reduction of Da results in smaller values of HTP and signifies the difference between the values of HTP predicted by the two interface models. © 2013 Elsevier Ltd. All rights reserved. Source

Hosseinkhani S.,Tarbiat Modares University
Cellular and Molecular Life Sciences | Year: 2011

Firefly luciferase-catalyzed reaction proceeds via the initial formation of an enzyme-bound luciferyl adenylate intermediate. The chemical origin of the color modulation in firefly bioluminescence has not been understood until recently. The presence of the same luciferin molecule, in combination with various mutated forms of luciferase, can emit light at slightly different wavelengths, ranging from red to yellow to green. A historical perspective of development in understanding of color emission mechanism is presented. To explain the variation in the color of the bioluminescence, different factors have been discussed and five hypotheses proposed for firefly bioluminescence color. On the basis of recent results, light-color modulation mechanism of firefly luciferase propose that the light emitter is the excited singlet state of OL- [1(OL-)], and light emission from 1(OL-) is modulated by the polarity of the active-site environment at the phenol/phenolate terminal of the benzothiazole fragment in oxyluciferin. © 2010 Springer Basel AG. Source

Ghannad M.,Shahrood University of Technology | Rahimi G.H.,Tarbiat Modares University | Nejad M.Z.,Yasouj University
Composites Part B: Engineering | Year: 2013

In this paper, using the first-order shear deformation theory (FSDT) and matched asymptotic method (MAM) of the perturbation theory, an analytical solution for deformations and stresses of axisymmetric clamped-clamped thick cylindrical shells with variable thickness made of functionally graded materials (FGMs) subjected to internal pressure are presented. The governing equations are a system of ordinary differential equations with variable coefficients. Using the MAM of the perturbation theory, these equations could be converted into a system of algebraic equations and two systems of differential equations with constant coefficients. The displacements and stresses along the radius and length have been plotted and distribution of these is compared with the solution using finite element method (FEM). © 2012 Elsevier Ltd. All rights reserved. Source

A novel technique called miniaturized homogeneous liquid-liquid extraction (MHLLE) followed by high performance liquid chromatographic-fluorescence detection (HPLC-FL) was developed for the extraction and determination of some polycyclic aromatic hydrocarbons (PAHs) as model for analytical problem in sediment samples. The method is based on the rapid extraction of PAHs from a methanolic sample solution into 0.5mL n-hexane, as a solvent of lower density than water. After addition of water, the extracting solvent immediately forms a distinct water-immiscible phase at the top of the vial, which can be easily separated, evaporated and re-dissolved in 25μL of methanol and injected to the HPLC instrument. The parameters affecting the extraction process such as type and volume of organic extraction solvent, extraction time, and salt addition were investigated and the partition coefficient between methanol/water-n-hexane phases was evaluated and used to predict the extraction efficiency. Under optimal conditions, the limits of detection were estimated for the individual PAHs as 3Sb (three times of the standard deviation of baseline) of the measured chromatogram, are in the range of 0.003-0.04ngg-1 for sediment samples. The relative recoveries of PAHs at spiking levels of 1.0ngg-1 for sediment samples were in the range of 81-92%. The method was also applied to a corresponding standard references materials (IAEA-408) successfully. The proposed method is very fast, simple, and sensitive without any need for stirring and centrifugation. © 2010 Elsevier B.V. Source

Shamsipur M.,Razi University | Asgari M.,Tarbiat Modares University | Maragheh M.G.,Electrochemistry Laboratory | Moosavi-Movahedi A.A.,University of Tehran
Bioelectrochemistry | Year: 2012

A robust and effective nanocomposite film-glassy carbon modified electrode based on multi-walled carbon nanotubes and a room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate was prepared by a layer-by-layer self-assembly method. The fabricated modified electrode was used as a novel impedimetric catalase nanobiosensor for the determination of H 2O 2. Direct electron transfer and electrocatalysis of catalase were fully investigated. The results suggested that catalase could be firmly adsorbed at the modified electrode. A pair of quasi-reversible redox peaks of catalase was observed in a 0.20M degassed phosphate buffer solution of pH 7.0. The nanocomposite film showed a pronounced increase in direct electron transfer between catalase and the electrode. The immobilized catalase exhibited an excellent electrocatalytic activity towards the reduction of H 2O 2. The electrochemical impedance spectroscopy measurements revealed that the charge transfer resistance decreases significantly after enzymatic reaction with hydrogen peroxide, so that the prepared modified electrode can be used for the detection of ultra traces of H 2O 2 (5-1700nM). © 2011 Elsevier B.V. Source

Cauliflower-like DNAs are stem-loop DNAs that are fabricated periodically in inverted repetitions from deoxyribonucleic acid phosphates (dNTPs) by loop-mediated isothermal amplification (LAMP). Cauliflower-like DNAs have ladder-shape behaviors on gel electrophoresis, and increasing the time of LAMP leads to multiplying the repetitions, stem-loops, and electrophoretic bands. Cauliflower-like DNAs were fabricated via LAMP using two loop primers, two bumper primers, dNTPs, a λ-phage DNA template, and a Bst DNA polymerase in 75- and 90-min periods. These times led to manufacturing two types of cauliflower-like DNAs with different contents of inverted repetitions and stem-loops, which were clearly indicated by two comparable electrophoresis patterns in agarose gel. LAMP-fabricated DNAs and natural dsB-DNA (salmon genomic DNA) were dialyzed in Gomori phosphate buffer (10 mM, pH 7.4) to be isolated from salts, nucleotides, and primers. Dialyzed DNAs were studied using UV spectroscopy, circular dichroism spectropolarimetry, and fluorescence spectrophotometry. Structural analyses indicated reduction of the molecular ellipticity and extinction coefficients in comparison with B-DNA. Also, cauliflower-like DNAs demonstrated less intrinsic and more extrinsic fluorescence in comparison with natural DNA. The overwinding and lengthening of the cauliflower-like configurations of LAMP DNAs led to changes in physical parameters of this type of DNA in comparison with natural DNA. The results obtained introduced new biomolecular characteristics of DNA macromolecules fabricated within a LAMP process and show the effects of more inverted repeats and stem-loops, which are manufactured by lengthening the process. Source

Barati R.,Tarbiat Modares University
Journal of Hydrologic Engineering | Year: 2011

The linear form of the Muskingum model has been widely applied to river flood routing. However, a nonlinear relationship between weighted-flow and storage volume exists in most rivers, making the use of the linear Muskingum model inappropriate. On the other hand, the application of the nonlinear Muskingum model suffers from hydrologic parameters estimation. The current study aims at presenting the objective approach of the Nelder-Mead simplex (NMS) algorithm for the purpose of estimating the parameters of the nonlinear Muskingum model. The performance of this algorithm is compared with other reported parameter estimation techniques together with a historical example. Results of the implementation of this procedure indicate that the NMS algorithm is efficient for the estimating parameters of the nonlinear Muskingum models. This algorithm is easy to be programmed, and it is quite efficient for finding an optimal solution very quickly. Although this technique requires an initial guess for the parameter estimation, results of the sensitivity analysis of the initial parameter values showed that in 84.8% of the cases, the optimum or near-optimum results are achieved. © 2011 American Society of Civil Engineers. Source

Veisi H.,Payame Noor University | Mohammadi P.,Payame Noor University | Gholami J.,Tarbiat Modares University
Applied Organometallic Chemistry | Year: 2014

Surface functionalization of magnetic nanoparticles is an elegant way to bridge the gap between heterogeneous and homogeneous catalysis. We have conveniently loaded sulfonic acid groups on amino-functionalized Fe3O4 nanoparticles affording sulfamic acid-functionalized magnetic Fe3O4 nanoparticles (MNPs/DAG-SO3H) as an active and stable magnetically separable acidic nanocatalyst, which was characterized using X-ray diffraction, Fourier transform infrared and energy-dispersive X-ray spectroscopies, scanning and transmission electron microscopies, vibrating sample magnetometry and elemental analysis. The catalytic activity of MNPs/DAG-SO3H was probed through one-pot synthesis of N-substituted pyrroles from γ-diketones and primary amines in aqueous phase at room temperature. The heterogeneous catalyst could be recovered easily by applying an external magnet device and reused many times without significant loss of its catalytic activity. Copyright © 2014 John Wiley & Sons, Ltd. Source

Jamekhorshid A.,Tarbiat Modares University | Sadrameli S.M.,University of Auckland | Farid M.,University of Auckland
Renewable and Sustainable Energy Reviews | Year: 2014

Microencapsulation of phase change materials (PCMs) is an effective way of enhancing their thermal conductivity and preventing possible interaction with the surrounding and leakage during the melting process, where there is no complete overview of the several methods and techniques for microencapsulation of different kinds of PCMs that leads to microcapsules with different morphology, structure, and thermal properties. In this paper, microencapsulation methods are perused and classified into three categories, i.e. physical, physic-chemical, and chemical methods. It summarizes the techniques used for microencapsulation of PCMs and hence provides a useful tool for the researchers working in this area. Among all the microencapsulation methods, the most common methods described in the literature for the production of microencapsulated phase change materials (MEPCMs) are interfacial polymerization, suspension polymerization, coacervation, emulsion polymerization, and spray drying. © 2014 Elsevier Ltd. Source

Mohebbi M.,K. N. Toosi University of Technology | Ghassemian H.,Tarbiat Modares University
Medical and Biological Engineering and Computing | Year: 2014

This paper presents an algorithm for predicting termination of paroxysmal atrial fibrillation (AF) attacks using features extracted from the atrial activity (AA) and heart rate variability (HRV) signals. First, AA signal was decomposed into a set of intrinsic mode functions (IMFs) using empirical mode decomposition method. Then, power spectrums of the AA and its IMFs (second, third, and forth components) were obtained, and the peak frequency of the power spectral densities were extracted. These features were complemented with three additional features consisting of mean, skewness, and kurtosis of the HRV signal. These seven features were then reduced to only two features by the generalized discriminant analysis technique. This not only reduces the number of the input features but also increases the classification accuracy by selecting most discriminating features. Finally, a linear classifier was used to classify AF episodes from AF termination database. This database consists of three types of AF episodes: N type (non-terminated AF episode), S type (terminated 1 min after the end of the record), and T type (terminated immediately after the end of the record). The obtained sensitivity, specificity, positive predictivity, and negative predictivity were 94, 97, 92, and 96 %, respectively. The important advantage of the proposed method comparing to the other existing approaches is that our algorithm can simultaneously discriminate three types of AF episodes with high accuracy. © 2014 International Federation for Medical and Biological Engineering. Source

Ahmadvand D.,Copenhagen University | Rahbarizadeh F.,Tarbiat Modares University | Moghimi S.M.,Copenhagen University
Current Opinion in Biotechnology | Year: 2011

Diverse technologies such as phage display, cell systematic evolution of ligands by exponential enrichment and related modifications thereof are generating a wide range of peptide-based and structured nucleic acid (aptamers)-based ligands for therapeutic and diagnostic interventions in an unbiased biological context. Their impressive affinity and unprecedented target specificity make these ligands as ideal small-sized candidates for conjugation to macromolecules and nanoparticulate matters, thus opening the path to new and sophisticated design solutions for targeted therapy, disease detection and diagnosis. Vascular beds of many organs and tissue, cancer, immune and stem cells are among the key targets. These technologies are evaluated and selected recent examples of innovative biological targeting and therapeutic interventions with phage-displayed peptides and aptamers are discussed. © 2011 Elsevier Ltd. Source

Farvaresh H.,University of Kurdistan | Sepehri M.M.,Tarbiat Modares University
Networks and Spatial Economics | Year: 2013

Discrete network design problem (DNDP) is generally formulated as a bi-level programming. Because of non-convexity of bi-level formulation of DNDP which stems from the equilibrium conditions, finding global optimal solutions are very demanding. In this paper, a new branch and bound algorithm being able to find exact solution of the problem is presented. A lower bound for the upper-level objective and its computation method are developed. Numerical experiments show that our algorithm is superior to previous algorithms in terms of both computation time and solution quality. The conducted experiments indicate that in most cases the first incumbent solution which is obtained within a few seconds is superior to the final solution of some of previous algorithms. © 2012 Springer Science+Business Media, LLC. Source

Alibeigloo A.,Tarbiat Modares University
Journal of Composite Materials | Year: 2015

In this paper, three-dimensional theory of elasticity is employed to investigate bending and free vibration behavior of simply supported cylindrical panel with special emphasis on incorporating viscoelastic interfacial imperfection. Analysis is carried out by using Fourier series along the axial and circumferential directions and state space technique along the radial direction. Time-dependent behavior is investigated by solving first-order differential equation of sliding displacement at the viscoelastic interfaces. Numerical results depict good agreement between the present numerical results and the available published results. In addition, the effects of solid, elastic and viscous interfaces, time, aspect ratio and mid radius to thickness ratio on the bending and vibration behavior of laminated cylindrical panel are discussed. © SAGE Publications. Source

Haghshenas H.F.,University of Nebraska - Lincoln | Khodaii A.,Amirkabir University of Technology | Khedmati M.,Tarbiat Modares University | Tapkin S.,Istanbul University
Construction and Building Materials | Year: 2015

Stripping - the most important mode of Hot Mix Asphalt (HMA) failure - is a problematic issue in the pavement performance and its maintenance. Identification and quantification of the pertinent parameters influencing on stripping process is a prerequisite for dealing with it effectively. Previous studies on stripping potential of HMA have focused on this issue based on empirical/semi-empirical models. In the present work Response Surface Methodology (RSM) was used for the study and optimization of pertinent factors, namely bitumen content employed, grading and lime content, in the stripping process of HMA. Tensile Strength Ratio (TSR) was chosen as the response for the evaluation of stripping potential of HMA using a Central Composite Design (CCD). The statistical analyses showed that second order polynomial models can successfully describe the relationship between the response and factors and the maximum Tensile Strength Ratio (TSR) is achieved at 5.73% bitumen content, 1.84% lime content and 65.30% of the materials passing sieve size 4.75 mm. © 2014 Elsevier Ltd. All rights reserved. Source

Samadikhah H.R.,Tarbiat Modares University
International journal of nanomedicine | Year: 2011

Cationic liposomes (CLs) are composed of phospholipid bilayers. One of the most important applications of these particles is in drug and gene delivery. However, using CLs to deliver therapeutic nucleic acids and drugs to target organs has some problems, including low transfection efficiency in vivo. The aim of this study was to develop novel CLs containing magnetite to overcome the deficiencies. CLs and magnetic cationic liposomes (MCLs) were prepared using the freeze-dried empty liposome method. Luciferase-harboring vectors (pGL3) were transferred into liposomes and the transfection efficiencies were determined by luciferase assay. Firefly luciferase is one of most popular reporter genes often used to measure the efficiency of gene transfer in vivo and in vitro. Different formulations of liposomes have been used for delivery of different kinds of gene reporters. Lipoplex (liposome-plasmid DNA complexes) formation was monitored by gel retardation assay. Size and charge of lipoplexes were determined using particle size analysis. Chinese hamster ovary cells were transfected by lipoplexes (liposome-pGL3); transfection efficiency and gene expression level was evaluated by luciferase assay. High transfection efficiency of plasmid by CLs and novel nanomagnetic CLs was achieved. Moreover, lipoplexes showed less cytotoxicity than polyethyleneimine and Lipofectamine. Novel liposome compositions (1,2-dipalmitoyl-sn-glycero-3-phosphocholine [DPPC]/dioctadecyldimethylammonium bromide [DOAB] and DPPC/cholesterol/DOAB) with high transfection efficiency can be useful in gene delivery in vitro. MCLs can also be used for targeted gene delivery, due to magnetic characteristic for conduction of genes or drugs to target organs. Source

Chahooki M.A.Z.,University of Yazd | Charkari N.M.,Tarbiat Modares University
Information Sciences | Year: 2014

Manifold learning is a non-linear method with the aim of finding a constructive way to embed the data from a high-dimensional space into a low-dimensional one. The improvement of shape classification is the major approach in this paper which is based on the continuity in feature space in accordance with the continuity in semantic one. In this regard, a non-linear approach is employed to map the shape feature vectors to a new space while their semantics become similar with human opinion, the Euclidean distance between two feature vectors would be closed. Shapes are described by four contour-based and region-based techniques by the proposed method. In other word, they are described in four observation spaces. Furthermore, a parameter space is learnt from multiple observation spaces based on fusion of dissimilarities in a supervised manner. Experimental results show the validity and efficiency of the proposed approach for shape classification over a variety of standard shape datasets. © 2013 Elsevier Inc. All rights reserved. Source

Yamini Y.,Tarbiat Modares University | Faraji M.,Standard Research Institute SRI
Journal of Pharmaceutical Analysis | Year: 2014

A simple, rapid and sensitive method termed as magnetic solid phase extraction (MSPE) combined with high-performance liquid chromatography- ultraviolet detector (HPLC-UV) has been proposed for the determination of trace amounts of chlorpromazine (CPZ) in water, urine and plasma samples. The separation and determination was performed on a C18 column under the optimal chromatographic conditions. Several factors influencing the extraction efficiency of CPZ, such as pH, surfactant and adsorbent amounts, ionic strength, extraction time, sample volume and desorption conditions, were studied and optimized. Under the optimal MSPE conditions, the extraction percentage of CPZ was 74%, 27% and 16% in water, urine and plasma samples, respectively. The limits of detection (LODs) of the proposed approach were 0.1, 5.0 and 10 ng/mL in water, urine and plasma samples, respectively. The relative standard deviations (RSDs) based on five replicate determinations at 10 ng/mL level of CPZ was 1.2%. Good linear behaviors over the investigated concentration ranges (0.25-300 ng/mL) with good coefficient of determination, R2>0. 9998, were obtained. Good spike recoveries with relative errors less than 9.0% were obtained when applying the proposed method to water, urine and plasma samples. © 2014 Xi'an Jiaotong University. Production and hosting by Elsevier B.V. All rights reserved. Source

Mirmomeni M.,Abadgaran Construction Company | Zarezadeh Mehrizi M.,Tarbiat Modares University | Marino M.A.,University of California at Davis
Computational Optimization and Applications | Year: 2010

Effective project management requires the development of a realistic plan and a clear communication of the plan from the beginning to the end of the project. The critical path method (CPM) of scheduling is the fundamental tool used to develop and interconnect project plans. Ensuring the integrity and transparency of those schedules is paramount for project success. The complex and discrete nature of the solution domain for such problems causes failing of traditional and gradient-based methods in finding the optimal or even feasible solution in some cases. The difficulties encountered in scheduling construction projects with resource constraints are highlighted by means of a simplified bridge construction problem and a basic masonry construction problem. The honey-bee mating optimization (HBMO) algorithm has been previously adopted to solve mathematical and engineering problems and has proven to be efficient for searching optimal solutions in large-problem domains. This paper presents the HBMO algorithm for scheduling projects with both constrained and unconstrained resources. Results show that the HBMO algorithm is applicable to projects with or without resource constraints. Furthermore, results obtained are promising and compare well with those of well-known heuristic approaches and gradient-based methods. © 2008 Springer Science+Business Media, LLC. Source

Alibeigloo A.,Tarbiat Modares University | Liew K.M.,City University of Hong Kong
International Journal of Applied Mechanics | Year: 2015

Based on the theory of elasticity, bending and free vibrational analyses of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) beam embedded in piezoelectric layers are carried out, using the state-space differential quadrature method (DQM). Applying the DQM to the governing differential equations and boundary conditions along the longitudinal directions, new state equations about state variables at discrete points are derived. By using the state-space technique across the thickness direction, semi- analytical closed form solutions are derived. The method is validated by comparing numerical results for beams without piezoelectric layers. Both the direct and the inverse piezoelectric effects are investigated and the influence of piezoelectric layers on the mechanical behavior of beam is studied. Furthermore, the effects of CNT volume fraction, kind of CNT distribution, length to thickness ratio and edge boundary conditions on the mechanical behavior of the beams are examined. © 2015 Imperial College Press. Source

Alibeigloo A.,Tarbiat Modares University
Composites Part B: Engineering | Year: 2015

In this study, static and free vibration analysis of laminated cross-ply rectangular plate with special emphasis on incorporating viscoelastic interface is investigated using three-dimensional theory of elasticity. The laminated plate is assumed to be simply-supported at four edges and is subjected to uniform pressure at the top surface. State space technique is used along the plate thickness to investigate the space dependent behavior where as time dependent behavior can be discussed by solving first order differential equation of sliding displacement at the viscoelastic interfaces. Numerical results depicts that the present method converges rapidly and good agreement is exist between the present results and the published results. Moreover, the effects of elastic and viscous interfaces, time, aspect ratio and length to thickness ratio on the bending and vibration behavior of laminated plate are studied. © 2015 Elsevier Ltd. All rights reserved. Source

Bolhassani A.,Pasteur Institute of Iran | Khavari A.,Pasteur Institute of Iran | Bathaie S.Z.,Tarbiat Modares University
Biochimica et Biophysica Acta - Reviews on Cancer | Year: 2014

Saffron, a spice derived from the flower of Crocus sativus, is rich in carotenoids. Two main natural carotenoids of saffron, crocin and crocetin, are responsible for its color. Preclinical studies have shown that dietary intake of some carotenoids have potent anti-tumor effects both in vitro and in vivo, suggesting their potential preventive and/or therapeutic roles in several tissues. The reports represent that the use of carotenoids without the potential for conversion to vitamin A may provide further protection and avoid toxicity. The mechanisms underlying cancer chemo-preventive activities of carotenoids include modulation of carcinogen metabolism, regulation of cell growth and cell cycle progression, inhibition of cell proliferation, anti-oxidant activity, immune modulation, enhancement of cell differentiation, stimulation of cell-to-cell gap junction communication, apoptosis and retinoid-dependent signaling. Taken together, different hypotheses for the antitumor actions of saffron and its components have been proposed such as a) the inhibitory effect on cellular DNA and RNA synthesis, but not on protein synthesis; b) the inhibitory effect on free radical chain reactions; c) the metabolic conversion of naturally occurring carotenoids to retinoids; d) the interaction of carotenoids with topoisomerase II, an enzyme involved in cellular DNA-protein interaction. Furthermore, the immunomodulatory activity of saffron was studied on driving toward Th1 and Th2 limbs of the immune system. In this mini-review, we briefly describe biochemical and immunological activities and chemo-preventive properties of saffron and natural carotenoids as an anticancer drug. © 2013 Elsevier B.V. Source

Lashgari A.,West Virginia University | Sayadi A.R.,Tarbiat Modares University
International Journal of Mining Science and Technology | Year: 2013

The purpose of this research was to develop a new approach in determination of overhaul and maintenance cost of loading equipment in surface mining. Two statistical models including univariate exponential regression (UER) and multivariate linear regression (MLR) were used in this study. Loading equipment parameters such as bucket capacity, machine weight, engine power, boom length, digging depth, and dumping height were considered as variables. The results obtained by models and mean absolute error rate indicate that these models can be applied as the useful tool in determination of overhaul and maintenance cost of loading equipment. The results of this study can be used by the decision-makers for the specific surface mining operations. © 2013 Published by Elsevier B.V. on behalf of China University of Mining & Technology. Source

Imaanpur A.,Tarbiat Modares University
Classical and Quantum Gravity | Year: 2013

Using canonical forms on S7, viewed as an SU(2) bundle over S4, we introduce consistent ansätze for the 4-form field strength of 11-dimensional supergravity and rederive the known squashed, stretched and the Englert solutions. Furthermore, by rewriting the metric of S7 as a U(1) bundle over CP3, we present yet more general ansätze. As a result, we find a new compactifying solution of the type AdS5 × CP3, where CP3 is stretched along its S2 fiber. We also find a new solution of AdS2 × H2 × S7 type in Euclidean space. © 2013 IOP Publishing Ltd. Source

Mortazavi S.M.J.,Shiraz University of Medical Sciences | Mozdarani H.,Tarbiat Modares University
International Journal of Radiation Research | Year: 2013

Some Areas of Ramsar, a city in northern Iran are among the world's well-known inhabited areas with highest levels of natural radiation. Annual exposure levels in these areas are up to 260 mGy y-1 and the mean exposure rate is about 10 mGy y- for a population of about 2000 residents. If elevated levels of natural radiation as high as a few hundred mSv per year is detrimental to health and leads to higher risks of genetic abnormalities and cancer, it should be evident in the residents of areas such as Ramsar. However, it has been reported that no detrimental biological effects have ever been detected in high natural background radiation areas. Some studies indicate that Ramsar residents not only show a significant increase in DNA repair but also demonstrate induction of radioadaptive response. There is currently a great debate over the shape of the dose-response curve for stochastic effects such as mutations and cancer after exposure to low doses of ionizing radiation. Linear-no-threshold (LNT) model predicts that every dose, no matter how low, carries some cancer risk. Lack of any proven detrimental effect in the residents of high natural background radiation areas of Ramsar may be due to the induction of nonlinear dose-response relationships which are not compatible with the widely accepted LNT hypothesis. Source

The Sistan area is located in the east of Iran, enclosure to Afghanistan border. It is a densely populated enclave in the scarcely populated arid area of the eastern part of Iran, where the life strongly depends on the shallow water of Hamoun Lake and wetlands in the delta of the Helmand River flows from the Hindukush Mountains in western Afghanistan. As the water resources are scarce in this arid region, the availability of freshwater in Hamoun Lake has caused many socioeconomic and environmental effects in study area during several years. Various categories of socioeconomic criteria have been defined that are influenced by the Hamoun wetland, namely employment, economic value of fish catch, reeds harvest and birds hunt, food supplying and its influence on the microclimate of the region and the severity of the sandstorms, health and finally provision of recreational opportunities in the region. On the other hand, the high evaporation rates in a very dry region and climatic fluctuations make very vulnerable ecosystem, causing several environmental challenges into human activities. Prolonged droughts due to decrease in annual rainfall in the Hirmand watershed based on climate change in the last decade have been recorded in this environmental hazardous area. Drying up of Hamoun Lake and dead reed system in the wetlands was monitored in the present study using the time series of satellite imagery. The lifelessness of Hamoun Lake has caused several environmental effects such as sandstorm and dust hazard, destroying vegetation, vanishing crop production, damage to fish and bird habitat, extensively decreasing reeds harvesting, reducing livestock and increasing wildlife death rates, increasing air pollution and consequently health problems, salty soil movement over the agriculture fields, etc., which have been identified as the outcome of this research. © 2012 Springer Science+Business Media B.V. Source

Ahmadi A.,Iran University of Science and Technology | Charwand M.,Tarbiat Modares University | Aghaei J.,Shiraz University of Technology
International Journal of Electrical Power and Energy Systems | Year: 2013

In the medium term planning, the objective of an electricity retailer is to configure its forward contract portfolio and to determine the selling price offered to its clients. To procure the electricity energy to be sold to the clients, a retailer has to face by two major challenges. Firstly, at buying electricity energy, it must cope with uncertain pool prices and sign forward contracts at higher average prices. Secondly, at selling electricity, it should handle the demand uncertainty and consider this fact that customers might choose a different retailer if the selling price is not competitive enough. In this paper the financial risk associated with the market price uncertainty is modeled using expected downside risk, which is incorporated explicitly as a constraint in the mixed-integer stochastic optimization problem. Roulette wheel mechanism and Lattice Monte Carlo Simulation (LMCS) are employed for random scenario generation wherein the stochastic optimization problem is converted into its respective deterministic equivalents. The proposed optimization problem is solved by a decomposition technique using Benders decomposition algorithm. A realistic case study is implemented to demonstrate the capability of the proposed method. © 2013 Elsevier Ltd. All rights reserved. Source

Masudy-Panah S.,Tarbiat Modares University
Solid State Communications | Year: 2011

In this paper, we have presented electric field dependence of the electron and hole impact ionization coefficients and threshold energies in submicron Si diodes with intrinsic region thicknesses down to 31 nm. To do so, we have used a nonlocal analysis, in order to take the effects of arbitrary distribution of ionization events in both space and time domains and the effects of enhancement in the average speed of those carriers which ionize early in their trajectories as well as nonuniform electric fields in the multiplication region and its surrounding ambient, carrier's dead space history and its spatial ionization rate, into consideration all in one comprehensive analytic model. © 2011 Elsevier Ltd. All rights reserved. Source

Aboutorabi L.,Payame Noor University | Morsali A.,Tarbiat Modares University
Ultrasonics Sonochemistry | Year: 2011

Nano-structured three-dimensional lead(II) coordination polymer, [Pb(μ6-Fum)]n (1); {Fum=Fumarate}, has been synthesized by sonochemical method and characterized by scanning electron microscopy, X-ray powder diffraction, elemental analyses and IR spectroscopy. Solvent effects on size and morphology of nano-structured compound 1 have been studied. Calcination of the nano-sized compound 1 at 600°C under air atmosphere yields PbO nanoparticles. The thermal stability of compound 1 both its bulk and nano-size has been studied by thermal gravimetric (TG) and differential thermal (DTA) analyses and compared each other. © 2010 Elsevier B.V. Source

Ramazani M.,Payame Noor University | Morsali A.,Tarbiat Modares University
Ultrasonics Sonochemistry | Year: 2011

Nanoplates of the three-dimensional coordination polymer, {[Cd 3(3-pyc)4(N3)2(H2O)] n (1), 3-pyc- = pyridine-3-carboxylate), have been synthesized by a sonochemical process and characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Cadmium(II) oxide nanoparticles were prepared from thermal decomposition in oleic acid and direct calcination of compound 1 at different temperatures. The thermal stability of nano-sized compound 1 was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). Results show that the size and morphology of the CdO nanoparticles are dependent upon the particles size of compound 1 and the thermolysis temperature. A decrease in the particle size of compound 1 leads to a decrease in the particle size of the CdO, while an increase in the processing temperature leads to an increase in the particle size of the produced cadmium(II) oxide nano-particles. © 2011 Elsevier B.V. All rights reserved. Source

Tavafian S.S.,Tarbiat Modares University | Jamshidi A.R.,Rheumatology Research Center | Mohammad K.,Tehran University of Medical Sciences
Clinical Journal of Pain | Year: 2011

Objective: This randomized clinical trial examined the efficacies of a group-based multidisciplinary rehabilitation program and oral drug treatment versus oral drug treatment alone in Iran. Methods: A total of 197 patients with chronic low back pain were randomized to either intervention group (n=97) receiving a group-based, 5-session multidisciplinary rehabilitation program plus oral medication or to control group (n=100) receiving just oral medication. At baseline and at 3 and 6-month follow-ups, patients filled out questionnaires on health-related quality of life (36-item Short-form General Health Survey) and disability Questionnaires (Quebec Disability Scale and Ronald-Morris Disability). Repeated measure analysis of variance was used to compare 2 groups during time. Results: The 2 groups were comparable regarding all baseline characteristics (P>0.05). There were significant differences within each group by time in terms of all subscales of 36-item Short-form (P<0.01) except for mental health (P=0.7). Furthermore, there were significant deferences between groups in terms of all domains of SF-36 scale except for general health (P=0.06), social function (P=0.08) and role emotional (P=0.7). Furthermore, according to the scores of Ronald-Morris Disability Questionnaire and Quebec Disability Scale, the disability of patients in the intervention group was improved over time significantly (P=0.01 and P<0.0001, respectively). Discussion: The findings revealed that the group-based multidisciplinary program could improve most domains of quality of life in chronic low back pain patients in the 6-month period. However, there were no significant differences between two groups in sub scales such as general health, social function and role emotional. © 2011 by Lippincott Williams & Wilkins. Source

Simab M.,Islamic Azad University at Science and Research of Fars | Haghifam M.R.,Tarbiat Modares University
International Journal of Electrical Power and Energy Systems | Year: 2012

In this paper, an algorithm is presented to obtain the parameters of reward and penalty schemes (RPSs) for each electric company using Data Envelopment Analysis (DEA). This algorithm is based on reliability indices and customers' value of interruptions. The companies' efficiency scores are calculated using a DEA methodology. The companies' efficiency scores are based on their performance in quality and the best performer is utilized as a benchmark for other companies. DEA efficiency score and historical quality level are used to set a quality target for each electric distribution company. In this algorithm more than one reliability index can be included in RPS and weighting value for each reliability index is calculated based on their impacts on the customers. The performance of the proposed algorithm is demonstrated in a case study to design RPS for Iranian electricity distribution companies. The results of the algorithm include DEA efficiency score, parameters of RPS and weighting value for each reliability index. © 2012 Elsevier Ltd. All rights reserved. Source

Nikoukar J.,Islamic Azad University at Tehran | Haghifam M.R.,Tarbiat Modares University
International Journal of Electrical Power and Energy Systems | Year: 2012

In the deregulated power system, it is necessary to develop an appropriate pricing scheme that can provide the useful economic information to market users, such as generation companies, transmission companies and customers. However, accurately assessment and allocating the transmission cost in the transmission pricing scheme is a challenge, although many methods have been proposed. The objective of this paper is to propose a simple transmission pricing scheme using tracing method based on the proportional tree, in which transmission fixed cost, congestion cost and loss cost are considered. A case study based on IEEE 24-bus test system is applied to assess the effectiveness of the cost allocation procedure. © 2012 Elsevier Ltd. All rights reserved. Source

Rostamnia S.,Islamic Azad University at Maragheh | Morsali A.,Tarbiat Modares University
RSC Advances | Year: 2014

The IRMOF-3 metal-organic framework (MOF) acts as a suitable green catalyst for the one-pot synthesis of dihydropyrimidinone and dihydropyridine derivatives through the Biginelli and Hantzsch reactions, and the desired products were obtained in high yields with short reaction times under mild solvent-free conditions. The MOFs can be isolated from the reaction mixture and reused. © 2014 The Royal Society of Chemistry. Source

Farahani R.Z.,Kingston University | Hekmatfar M.,Amirkabir University of Technology | Arabani A.B.,Wayne State University | Nikbakhsh E.,Tarbiat Modares University
Computers and Industrial Engineering | Year: 2013

Hub location problem (HLP) is a relatively new extension of classical facility location problems. Hubs are facilities that work as consolidation, connecting, and switching points for flows between stipulated origins and destinations. While there are few review papers on hub location problems, the most recent one (Alumur and Kara, 2008. Network hub location problems: The state of the art. European Journal of Operational Research, 190, 1-21) considers solely studies on network-type hub location models prior to early 2007. Therefore, this paper focuses on reviewing the most recent advances in HLP from 2007 up to now. In this paper, a review of all variants of HLPs (i.e., network, continuous, and discrete HLPs) is provided. In particular, mathematical models, solution methods, main specifications, and applications of HLPs are discussed. Furthermore, some case studies illustrating real-world applications of HLPs are briefly introduced. At the end, future research directions and trends will be presented. © 2013 Elsevier Ltd. All rights reserved. Source

Beiranvand R.,Tarbiat Modares University
Review of Scientific Instruments | Year: 2013

Using the Helmholtz coils system is one of the most suitable approaches which have been introduced for generating uniform magnetic fields. In this paper, uniformity of the generated magnetic field by a practical one-dimensional (1D) Helmholtz coils system has been analyzed, mathematically. For this purpose, relationships between the magnetic field uniformity and different practical unavoidable mismatches have been extracted. The theoretical analysis clearly demonstrates the effect of assembly misalignments and manufacturing mismatches on the magnetic field achieved by a practical 1D Helmholtz coils system. The given analyses have been confirmed by the experimental results which are in good agreement with the calculated values. This analysis and the experimental results illustrate that to achieve a very high uniform magnetic field, practical assembly misalignments, and manufacturing mismatches must be as small as possible, and the background magnetic field distortion must be avoided, too. The results of this work are important in the design of instruments and systems where Helmholtz coils are used. © 2013 AIP Publishing LLC. Source

Movahedi F.,Standard Research Institute | Masrouri H.,Standard Research Institute | Kassaee M.Z.,Tarbiat Modares University
Journal of Molecular Catalysis A: Chemical | Year: 2014

Silver nanoparticles were immobilized on ionic liquid modified zinc oxide nanoparticles leading to a ZnO-IL/Ag NPs catalyst, which exhibits high catalytic performance in the synthesis of propargylamines through one-pot three-component condensation reaction of aldehydes, amines, and alkynes in water. The as-prepared catalyst was characterized by ICP-AES, FT-IR, XRD, SEM, and TEM. The catalyst was easily recycled and reused at least five times without significant loss of its catalytic activity. © 2014 Elsevier B.V. Source

Zavvari M.,Islamic Azad University at Urmia | Ahmadi V.,Tarbiat Modares University
Applied Optics | Year: 2013

A novel design for a quantum dot infrared photodetector (QDIP) is proposed based on avalanche multiplication and is expected to be used as a single photon detector at mid-IR. A high field multiplication region is added to a conventional QDIP in separate absorption, charge, and multiplication structures to intensify incoming photocurrent generated in the absorption region. The absorption region of the photodetector consists of quantum dot layers that are responsible for absorption of mid-IR wavelengths. Because of higher operation voltages in gated-mode operation, resonant tunneling barriers are also included in the absorption region to prevent higher dark currents. The absorption region is designed for operation at ?8 ?m. During the gate pulse period, photo-generated electrons can trigger an avalanche and produce an output pulse. For this detector, the dark count rate (DCR) and single photon quantum efficiency (SPQE) are calculated at different temperatures. SPQE with peak of about 0. 3 for T50 K is obtained. For higher temperatures, about T 120 K, SPQE is very low due to the contribution of dark carriers generated in the quantum dot absorption region. © 2013 Optical Society of America. Source

Akbari Moornani K.,Tarbiat Modares University | Haeri M.,Sharif University of Technology
Transactions of the Institute of Measurement and Control | Year: 2013

This paper considers a closed-loop system consisting of a fractional/integer order system and a fractional PID controller. Assuming that the uncertain coefficients of the fractional PID controller lie in some known intervals independently (i.e. that controller is a member of an interval family), the paper presents some easy to use theorems to investigate the robust bounded-input bounded-output stability of the resultant closed-loop system. Moreover, a finite frequency bound required in drawing the related graphs has also been provided. Finally, some numerical examples are presented to illustrate the results. © 2012 The Author(s). Source

Forouzanfar M.,Amirkabir University of Technology | Doustmohammadi A.,Amirkabir University of Technology | Hasanzadeh S.,Tarbiat Modares University | Shakouri G H.,University of Tehran
Applied Energy | Year: 2012

In this paper, a new multi-level genetic programming (MLGP) approach is introduced for forecasting transport energy demand (TED) in Iran. It is shown that the result obtained here has smaller error compared with the result obtained using neural network or fuzzy linear regression approach. The forecast uses historical energy data from 1968 to 2002 and it is based on three parameters; gross domestic product (GDP), population (POP), and the number of vehicles (VEH). The approach taken in this paper is based on genetic programming (GP) and the multi-level part of the name comes from the fact that we use GP in two different levels. At the first level, GP is used to obtain the time series model of the three parameters, GDP, POP, and VEH, and forecast those parameters for the time interval that their actual data are not available, and at the second level GP is used one more time to forecast TED based on available data for TED along with the data that are either available or predicted for the three parameters discussed earlier. Actual data from 1968 to 2002 are used for training and the data for years 2003-2005 are used to test the GP model. We have limited ourselves to these data ranges so that we could compare our results with the existing ones in the literature. The estimation GP for the model is formulated as a nonlinear optimization problem and it is solved numerically. © 2011 Elsevier Ltd. Source

Bakhshi B.,Tarbiat Modares University
Reviews in Medical Microbiology | Year: 2015

Cholera toxin is the most important virulence factor of epidemic Vibrio cholerae strains. It is encoded by ctxAB operon that is a part of the genome of a filamentous bacteriophage (CTXphi). This bacteriophage plays an important role in the evolution and pathogenesis of V. cholerae and genetic variations that occur within the genome of this bacteriophage affect V. cholerae toxicity and potential to cause epidemics and can be used as a powerful tool in epidemiological investigations. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. Source

Milani A.E.,Islamic Azad University at Tehran | Haghifam M.R.,Tarbiat Modares University
Mathematical and Computer Modelling | Year: 2013

Power loss is one of the most important issues when dealing with distribution networks. Due to the nature of power loss, it can be an inseparable part of these networks. This is while an optimal reconfiguration is a great optimization procedure to power loss reduction in distribution networks. Moreover, to perform optimal dynamic reconfiguration, determining optimal time intervals and detecting the most proper time points greatly affects the total benefit achieved from this process. This benefit includes the cost of reconfiguration and the benefit of power loss reduction. This paper proposes an evolutionary approach for optimal time interval determination. In this paper basic reconfiguration models are discussed to form an optimal time interval model gradually. The Genetic Algorithm (GA) is used to solve the suggested model while the proposed method is implemented on an IEEE-33 Bus network. In order to examine the effectiveness of the proposed method, a comparison is done with other similar procedures. Also, in order to validate the numerical results, further compression is done with a method using a Binary Particle Swarm Optimization (BPSO) algorithm rather than the GA. © 2011 Elsevier Ltd. Source

Arashloo S.R.,Tarbiat Modares University
Machine Vision and Applications | Year: 2016

Recently, with the advent of powerful optimisation algorithms for Markov random fields (MRFs), priors of high arity (more than two) have been put into practice more widely. The statistical relationship between object parts encoding shape in a covariant space, also known as the point distribution model (PDM), is a widely employed technique in computer vision which has been largely overlooked in the context of higher-order MRF models. This paper focuses on such higher-order statistical shape priors and illustrates that in a spatial transformation invariant space, these models can be formulated as convex quadratic programmes. As such, the associated energy of a PDM may be optimised efficiently using a variety of different dedicated algorithms. Moreover, it is shown that such an approach in the context of graph matching can be utilised to incorporate both a global rigid and a non-rigid deformation prior into the problem in a parametric form, a problem which has been rarely addressed in the literature. The paper then illustrates an application of PDM priors for different tasks using graphical models incorporating factors of different cardinalities. © 2016 Springer-Verlag Berlin Heidelberg Source

Bending analysis of sandwich circular plate with functionally grade core layer subjected to thermo-mechanical load is carried out using generalized differential quadrature (GDQ) method. The facing layers are made by metal and ceramic whereas the core layer is functionally graded materials composed of metal and ceramic material with distribution according to exponential function. Sandwich plate has various edges boundary conditions. Temperature distribution in three dimensions is obtained by solving heat conduction governing equation analytically. From combination of three dimensional governing equilibrium equations and constitutive relations, state space equations are derived. Applying GDQ method to the state space equations along the radial direction, semi-analytical solution can be obtained. After checking the convergence of the present approach, validation is carried out by comparing numerical results with the available results in open literature. Moreover, parametric study is presented to show the effects of the gradient direction, outer radius to thickness ratio, edges boundary conditions on the thermoelastic behavior of sandwich annular plates. © 2015 Elsevier Ltd. Source

Shamsipur M.,Razi University | Naseri M.T.,Tarbiat Modares University | Babri M.,Defense Chemical Research Laboratory DCRL
Journal of Pharmaceutical and Biomedical Analysis | Year: 2013

A simple, rapid and sensitive method based on dispersive derivatization liquid-liquid microextraction (DDLLME) combined with gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) was developed and validated for the determination of prostate cancer metabolite biomarkers, including sarcosine, alanine, leucine and proline, in human urine samples. Dispersive derivatization using isobutyl chloroformate has been successfully employed to identify the amino acids of interest in ngmL-1 concentrations. Under the optimum experimental conditions, the detection limits of the amino acids were in the range of 0.05-0.1ngmL-1. The enrichment factor and relative recovery for the target amino acids were in the range of 140-155 and 93.8-106%, respectively. The proposed method showed good linearity (correlation coefficients >0.997), and good intra-day (below 7%) and inter-day precision (below 10%). This protocol provides a rapid, simple, selective and sensitive tool to quantify sarcosine and endogenous urinary metabolite for prostate cancer diagnosis and for a screening test. © 2013 Elsevier B.V. Source

Bejari H.,University of Sistan and Baluchestan | Khademi Hamidi J.,Tarbiat Modares University
Rock Mechanics and Rock Engineering | Year: 2013

Rock mass parameters including weak surfaces are the most important parameters which should be taken into account for an accurate analysis of the rock penetration by disc cutters. To date, many experimental, theoretical, and numerical simulation-based researches have been carried out on the interaction of TBM disc cutter performance and joint spacing and orientation. In this study, the simultaneous effects of joint spacing and orientation on rock indentation and fragmentation process by two TBM disc cutters are investigated by using the discrete element method (DEM). To do this, three intervals of joint spacing together with seven representative values of joint orientation are taken into consideration. Based on the results of geological site investigations, the main lithological units through which the tunnel was driven consist of sandstone, tuff, gypsum, shale, and limestone layers. Source

Keramati A.,University of Tehran | Afshari-Mofrad M.,Tarbiat Modares University | Kamrani A.,University of Tehran
Computers and Education | Year: 2011

Although many researchers have studied different factors which affect E-Learning outcomes, there is little research on assessment of the intervening role of readiness factors in E-Learning outcomes. This study proposes a conceptual model to determine the role of readiness factors in the relationship between E-Learning factors and E-Learning outcomes. Readiness factors are divided into three main groups including: technical, organizational and social. A questionnaire was completed by 96 respondents. This sample consists of teachers at Tehran high schools who are utilizing a technology-based educating. Hierarchical regression analysis is done and its results strongly support the appropriateness of the proposed model and prove that readiness factors variable plays a moderating role in the relationship between E-Learning factors and outcomes. Also latent moderated structuring (LMS) technique and MPLUS3 software are used to determine each variable's ranking. Results show that organizational readiness factors have the most important effect on E-Learning outcomes. Also teachers' motivation and training is the most important factor in E-Learning. Findings of this research will be helpful for both academics and practitioners of E-Learning systems. © 2011 Elsevier Ltd. All rights reserved. Source

Thermoelastic analysis of composite cylindrical panel reinforced by single walled carbon nanotube (SWCNT) with simply supported edges by using three-dimensional theory of elasticity. Thermoelastic constant of carbon nanotube (CNT) as well as polymer matrix are assumed to be temperature independent. The volume fractions of oriented, straight SWCNTs are assumed to be uniformly distributed (UD) and or graded in the thickness direction according to four kinds of CNT distributions. The effective material properties of the nanocomposite cylindrical panel are based on rule of mixture. At first temperature distribution in three dimensions is obtained by solving heat conduction differential equation with variable coefficient. By applying Fourier series expansion to the stress and displacement fields along the axial and circumferential direction and state space technique along the radial direction thermoelastic analysis is carried out. Moreover, effects of volume fraction of carbon nanotube, uniform distribution and functionally graded distribution of CNT, mid radius to thickness ratio, length to mid radius ratio, thermal and mechanical surface boundary conditions on bending behavior of FG-CNTRC cylindrical panel are also examined. © 2015 Elsevier Ltd. All rights reserved. Source

Vafakhah M.,Tarbiat Modares University
Arabian Journal of Geosciences | Year: 2013

The present research was carried out by using artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS), cokriging (CK) and ordinary kriging (OK) using the rainfall and streamflow data for suspended sediment load forecasting. For this reason, the time series of daily rainfall (mm), streamflow (m3/s), and suspended sediment load (tons/day) data were used from the Kojor forest watershed near the Caspian Sea between 28 October 2007 and 21 September 2010 (776 days). Root mean square error, efficiency coefficient, mean absolute error, and mean relative error statistics are used for evaluating the accuracy of the ANN, ANFIS, CK, and OK models. In the first part of the study, various combinations of current daily rainfall, streamflow and past daily rainfall, streamflow data are used as inputs to the neural network and neuro-fuzzy computing technique so as to estimate current suspended sediment. Also, the accuracy of the ANN and ANFIS models are compared together in suspended sediment load forecasting. Comparison results reveal that the ANFIS model provided better estimation than the ANN model. In the second part of the study, the ANN and ANFIS models are compared with OK and CK. The comparison results reveal that CK was a better estimation than the OK. The ANFIS and ANN models also provided better estimation than the OK and CK models. © 2012 Saudi Society for Geosciences. Source

Salehnia M.,Tarbiat Modares University | Zavareh S.,Damghan University
International Journal of Fertility and Sterility | Year: 2013

Oocyte maturation and embryo development are controlled by intra-ovarian factors such as steroid hormones. Progesterone (P4) exists in the follicular fluid that contributes to normal mammalian ovarian function and has several critical functions during embryo development and implantation, including endometrial receptivity, embryonic survival during gestation and transformation of the endometrial stromal cells to decidual cells. It is well known that the physiological effects of P4 during the pre-implantation stages of some mammal's embryos are mediated by P4 receptors and their gene expression is determined. The effects of P4 on oocytes and embryo development have been assessed by some investigations, with contradictory results. P4, a dominant steroid in follicular fluid at approximately 18 hours after the luteinizing hormone (LH) surge may have a critical role in maturation of oocytes at the germinal stage. However, it has been shown that different concentrations of P4 could not improve in vitro maturation rates of germinal vesicles (GV) in cumulus oocyte complexes (COCs) and cumulus denuded oocytes (CDOs). Culture media supplemented with P4 significantly improved mouse embryo development. In addition, an in vivo experimental design has shown high blastocyst survival and implantation rates in P4-treated mice. In this review we explain some of the findings that pertain to the effects of P4 on oocyte maturation and embryo development both in vitro and in vivo. Source

Hekmatara H.,Guilan University | Seifi M.,Guilan University | Forooraghi K.,Tarbiat Modares University
Journal of Magnetism and Magnetic Materials | Year: 2013

This study investigated the microwave absorption properties of magnetic modified multiwall carbon nanotubes (MWCNTs) with different alignments to the electric field (E vector) of the incident electromagnetic (EM) waves. MWCNTs were decorated with Fe3O4 nanoparticles using the wet chemical method and the resulting MWCNT/Fe3O4 was then used as a filler in a MWCNT/Fe3O4/epoxy resin composite at different weight-to-epoxy-resin ratios (2%, 5%, and 8%) with good uniformity and alignment. For each filler concentration, three samples were produced with different alignments of carbon nanotubes using the solution-casting method. For sample one, the nanotube axis (k) was parallel to the E vector of the EM wave, for sample two, k was perpendicular to E, and the third sample contained randomly oriented nanotubes. Magnetic MWCNTs were exposed to a 0.4 T magnetic field in the desired direction to achieve the desired alignment of carbon nanotubes in epoxy resin. Microwave absorption characterization of the considered ranging band (X-band) at all concentrations where the alignment of MWCNT/Fe3O4 was parallel to the incident E vector showed increased absorption. Samples with a perpendicular alignment of MWCNT/Fe 3O4 to incident E had the lowest absorption. Samples containing 2 wt% and 8 wt% MWCNT/Fe3O4 aligned parallel to E and had reflection losses exceeding 14.4 dB and 23.6 dB, respectively, over a 10-11 GHz range. The 5 wt% parallel aligned MWCNT/Fe3O4 showed an absorbing peak of 27 dB and a bandwidth broadened to 1.2 GHz. © 2013 Elsevier B.V. Source

Motamedian E.,Tarbiat Modares University
Computers and Chemical Engineering | Year: 2015

Finding all optimal solutions for a metabolic model is the challenge of metabolic modeling, but there is no practical algorithm for large scale models. A two-phase algorithm is proposed here to systematically identify all optimal solutions. In phase 1, the model is reduced using the FVA approach; in phase 2, all optimal solutions are searched by the addition of a binary variable to convert the model to an MILP problem. The proposed approach proved itself to be a more tractable method for large scale metabolic models when compared with the previously proposed algorithm. The algorithm was implemented on a metabolic model of Escherichia coli (iJR904) to find all optimal flux distributions. The model was reduced from 1076 to 80 fluxes and from 998 to 54 equations and the MILP problem was solved, resulting in 30,744 various flux distributions. For the first time, this number of optimal solutions has been reported. © 2014 Elsevier Ltd. Source

Falaghi H.,Birjand University | Singh C.,Texas A&M University | Haghifam M.-R.,Tarbiat Modares University | Ramezani M.,Birjand University
International Journal of Electrical Power and Energy Systems | Year: 2011

In this paper, a framework is presented to solve the problem of multistage distribution system expansion planning in which installation and/or reinforcement of substations, feeders and distributed generation units are taken into consideration as possible solutions for system capacity expansion. The proposed formulation considers investment, operation, and outage costs of the system. The expansion methodology is based on pseudo-dynamic procedure. A combined genetic algorithm (GA) and optimal power flow (OPF) is developed as an optimization tool to solve the problem. The performance of the proposed approach is assessed and illustrated by numerical studies on a typical distribution system. © 2011 Elsevier Ltd. All rights reserved. Source

Asadi Noughabi A.,Tarbiat Modares University
Global journal of health science | Year: 2013

It seems necessary to study the health status of this age group to promote their health and prevent disease as well as care planning. In order to achieve this goal, a clear definition of the concept of elderly health is essential. Hybrid concept analysis, our research design, utilizes both theoretical analysis of literature and empirical observation to define a concept. We chose the hybrid concept analysis method because its inclusion of old people perspectives enriches the limited health research literature. The method consists of three phases: theory, fieldwork, and analysis. In comparison, we can conclude that health in the elderly people is something more than the absence of illness and 4 physical, mental, social and spiritual domains which are referred to in the definition of a theoretical stage are supported by the findings. The relative health was also proposed against the complete welfare and comfort for the elderly and it showed that their expectations are less than their ages. In addition, the elderly have expressed the family as a preference and the researcher believes that this theme is context based because it has emerged following the interview. Since the family has a special place according to the Iranian culture and religion and the family health is a priority in their health. In addition, the daily activities have been raised as a major theme that can be considered as the physical health but the elderly have expressed it apart from the physical health. Health among the old is a concept that is affected by genetic, environmental, healthcare services and lifestyle-related factors and involves proportional physical, mental, social, familial, spiritual, and economical welfare along with the ability to handle daily life activities which is measurable through medical and functional approaches. Source

Hiemstra T.,Wageningen University | Antelo J.,Wageningen University | Rahnemaie R.,Tarbiat Modares University | Riemsdijk W.H.v.,Wageningen University
Geochimica et Cosmochimica Acta | Year: 2010

Information on the particle size and reactive surface area of natural samples is essential for the application of surface complexation models (SCM) to predict bioavailability, toxicity, and transport of elements in the natural environment. In addition, this information will be of great help to enlighten views on the formation, stability, and structure of nanoparticle associations of natural organic matter (NOM) and natural oxide particles. Phosphate is proposed as a natively present probe ion to derive the effective reactive surface area of natural samples. In the suggested method, natural samples are equilibrated (≥10 days) with 0.5 M NaHCO3 (pH = 8.5) at various solid-solution ratios. This matrix fixes the pH and ionic strength, suppresses the influence of Ca2+ and Mg2+ ions by precipitation these in solid carbonates, and removes NOM due to the addition of activated carbon in excess, collectively leading to the dominance of the PO4-CO3 interaction in the system. The data have been interpreted with the charge distribution (CD) model, calibrated for goethite, and the analysis results in an effective reactive surface area (SA) and a reversibly bound phosphate loading Γ for a series of top soils. The oxidic SA varies between about 3-30 m2/g sample for a large series of representative agricultural top soils. Scaling of our data to the total iron and aluminum oxide content (dithionite-citrate-bicarbonate extractable), results in the specific surface area between about 200-1200 m2/g oxide for most soils, i.e. the oxide particles are nano-sized with an equivalent diameter in the order of ∼1-10 nm if considered as non-porous spheres. For the top soils, the effective surface area and the soil organic carbon fraction are strongly correlated. The oxide particles are embedded in a matrix of organic carbon (OC), equivalent to ∼1.4 ± 0.2 mg OC/m2 oxide for many soils of the collection, forming a NOM-mineral nanoparticle association with an average NOM volume fraction of ∼80%. The average mass density of such a NOM-mineral association is ∼1700 ± 100 kg/m3 (i.e. high-density NOM). The amount of reversibly bound phosphate is rather close to the amount of phosphate that is extractable with oxalate. The phosphate loading varies remarkably (Γ ≈ 1-3 μmol/m2 oxide) in the samples. As discussed in part II of this paper series (Hiemstra et al., 2010), the phosphate loading (Γ) of field samples is suppressed by surface complexation of NOM, where hydrophilic, fulvic, and humic acids act as a competitor for (an)ions via site competition and electrostatic interaction. © 2009 Elsevier Ltd. All rights reserved. Source

Abrishamifar A.,Iran University of Science and Technology | Ahmad A.A.,Iran University of Science and Technology | Mohamadian M.,Tarbiat Modares University
IEEE Transactions on Power Electronics | Year: 2012

Sliding mode control (SMC) is recognized as robust controller with a high stability in a wide range of operating conditions, although it suffers from chattering problem. In addition, it cannot be directly applied to multiswitches power converters. In this paper, a high performance and fixed switching frequency sliding mode controller is proposed for a single-phase unipolar inverter. The chattering problem of SMC is eliminated by smoothing the control law in a narrow boundary layer, and a pulsewidth modulator produces the fixed frequency switching law for the inverter. The smoothing procedure is based on limitation of pulsewidth modulator. Although the smoothed control law limits the performance of SMC, regulation and dynamic response of the inverter output voltage are in an acceptable superior range. The performance of the proposed controller is verified by both simulation and experiments on a prototype 6-kVA inverter. The experimental results show that the total harmonic distortion of the output voltage is less than 1.1% and 1.7% at maximum linear and nonlinear load, respectively. Furthermore, the output dynamic performance of the inverter strictly conforms the standard IEC62040-3. Moreover, the measured efficiency of the inverter in the worst condition is better than 95.5%. © 2006 IEEE. Source

Delfani S.,Building Research Institute, Egypt | Pasdarshahri H.,Tarbiat Modares University | Karami M.,University of Tehran
Energy and Buildings | Year: 2012

Nowadays, use of air-to-air heat recovery system combined to the cooling system is becoming necessary. Types of combination heat recovery and air conditioner must provide the comfort conditions and better indoor air quality for occupants in any climatic conditions. In this research, four types of air conditioning systems are evaluated experimentally. In each case, the amount of energy consumption by the aim of providing the thermal comfort, for various outdoor climatic conditions in hot and humid regions is evaluated and compared. The contour plot of each experimental case is made, which shows the net energy consumption of systems based on the outdoor design condition. Finally, according to the experimental results, for selected hot and humid cities of Asia's south and west countries (such as Abadan, Kuwait, Doha, Dehli, Bangkok), the rate of energy consumption of each cooling systems is calculated. It is shown that by using the heat recovery, energy consumption will reduce about 11-32% based on the system approach. © 2012 Elsevier B.V. All rights reserved. Source

Saremi A.,Arak University | Asghari M.,Tarbiat Modares University | Ghorbani A.,Arak University
Journal of Sports Sciences | Year: 2010

Omentin-1 is a newly discovered protein expressed and secreted from visceral adipose tissue that increases insulin sensitivity. We examined the effects of 12 weeks of aerobic training on serum omentin-1 concentrations together with cardiovascular risk factors in overweight and obese men. Eighteen overweight and obese participants (age 43.1±4.7 years, BMI≥25 kg·m-2) were assigned to exercise training (n=9) and control (n=9) groups. A matched control group of normal weight participants (n=8; age 42.2±3.8 years, BMI<25 kg·m-2) were also recruited for baseline comparison. The obese exercise group participated in 12 weeks of progressive aerobic training 5 days a week. Measures of serum omentin-1, insulin resistance, lipid profiles, blood pressure, and body composition were obtained before and after the 12 weeks. At baseline, normal weight participants had significantly higher serum omentin-1 concentrations than overweight and obese participants, and there were inverse correlations between omentin-1 and each of waist circumference, fasting glucose, insulin resistance, total cholesterol, triglyceride, and systolic blood pressure (P<0.05). After the aerobic training, waist circumference, percent body fat, fasting glucose, insulin resistance, triglyceride, total cholesterol, low-density lipoprotein cholesterol, and systolic blood pressure were all significantly decreased (P<0.05). In contrast, serum omentin-1 concentration was significantly increased after the aerobic programme (P<0.05), and correlated with changes in insulin resistance (r=-0.67, P=0.04), glucose (r=-0.65, P=0.05), waist circumference (r=-0.70, P=0.03), and aerobic fitness r=-0.68, P=0.04). Aerobic training resulted in an improvement in cardiometabolic risk factors in obese participants, and this improvement was accompanied by increased omentin-1 concentrations. © 2010 Taylor & Francis. Source

Aghazadeh M.,Tarbiat Modares University | Aghazadeh M.,Material Research School | Golikand A.N.,Material Research School | Ghaemi M.,Golestan University
International Journal of Hydrogen Energy | Year: 2011

Nickel hydroxide was deposited via cathodic electrodeposition from low-temperature 0.005 M NiCl2 bath without using any surfactant or template. The cathodic current density was 1 mA cm-2 and stainless steel was used as the cathode. The XRD pattern confirmed that the prepared sample has a pure brucite crystal phase of β-Ni(OH)2 and the broadening of diffraction peaks showed that the particles size of the prepared β-Ni(OH)2 is extremely small. Thermal behavior and composition of the prepared β-Ni(OH)2 were investigated by DSC-TG and FT-IR analyses. Morphological characterization by SEM and TEM revealed that β-Ni(OH)2 is composed of well dispersed ultrafine particles with size of about 5 nm. The electrochemical properties of the prepared nanoparticles were studied by means of cyclic voltammetry (CV) and galvanostatic charge-discharge tests in 1 M KOH. The prepared β-Ni(OH)2 nanoparticles showed excellent capacitance behavior of 740 F g-1 in the potential window of 0-0.55 V vs. Ag/AgCl. These results make the β-Ni(OH)2 nanoparticles as a promising candidate for the supercapacitor electrodes. © 2011 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source

Light olefins such as ethylene and propylene, are considered as main raw materials for the production of numerous plastic materials, synthesis fibers and rubbers in the petrochemical industry. The conventional process for the production of light olefins is thermal cracking in the presence of steam called Steam Cracking (SC). This has been the main technology for the production of olefins for more than ninety years. This technology has reached to its full capacity and cannot accommodate excessive demands of the petrochemical industry although still 95% of the light olefins are produced by this technology. In addition there are a few drawbacks for this technology such as en extensive energy consumption, and production of greenhouse gasses. An alternative and promising route for the production of light olefins which consumes less energy and produces fewer pollutants to the environment is Thermal Catalytic Cracking (TCC). This paper reviews the main research works done on the process in the literature in the last five decades. An eight-lump mathematical model is presented for the catalytic cracking kinetics. Some of the main experimental laboratory setup systems in the world have also been reviewed and parts of the results are presented and discussed. © 2016 Elsevier Ltd. All rights reserved. Source