IFC
text
article
2014
per
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
0
0
http://mme.modares.ac.ir/article_11300_3b485220cddeeac7c403c6cd704df0e2.pdf
Mechanical Effects of Extracellular Matrix on Growth and Migration of Endothelial Cells in Tumorinduced Angiogenesis
Madjid
Soltani
عضو هیئت علمی دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Hossein
Bazmara
K. N. T. University of Technology
author
Mostafa
Sefidgar
K. N. T. University of Technology
author
Madjid
Bazargan
K. N. T. University of Technology
author
Seyyed Mojtaba
Musavi Naeenian
K. N. T. University of Technology
author
text
article
2014
per
Tumor induced angiogenesis is the bridge between benign and malignant tumor growth stages. In this process, growth and migration of endothelial cells build capillaries to supply the tumor with blood for its further growth. Regarding the importance of capillary formation and blood flow in angiogenesis, simulation of this phenomenon plays important role in tumor growth and cancer development studies. In this work, considering intracellular, cellular, and extracellular scales a mathematical model of tumorinduced angiogenesis is used to consider mechanical effects of extracellular matrix on growth and migration of endothelial cells. These effects are matrix density and its fiber length. In this study, to model cellular dynamics, a discrete lattice based Monte Carlo method is used. Results show that migration of endothelial cells and development of capillaries are possible in a specified range of matrix density and matrix fiber length. Based on the results, medium matrix densities and low fiber length provide a suitable environment for capillaries growth and development. The model is a promising tool for modeling tumor induced angiogenesis and is a base for development of models for loop formation and blood flow in capillaries around tumor.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
1
9
http://mme.modares.ac.ir/article_11197_8570c4e1fc0fc741855604e7adeccacf.pdf
Study on the Performance of Spur Gears in Mixed Elastohydrodynamic Lubrication
Saleh
Akbarzadeh
استادیار دانشگاه صنعتی اصفهان
author
Morteza
Parsa
Department of Mechanical Engineering, Isfahan University of Technology
author
text
article
2014
per
Gears are widely used to transmit power between two parallel shafts. Study on the lubricant film which is formed between the engaged teeth of pinion and gear is of high importance in predicting the performance of the power transmission system as well as surface failure and wear. Gear surfaces in comparison to rolling element bearings have a higher surface roughness and thus considering the surface roughness is important in gear analysis. In this research, the performance of a piniongear system operating under mixedelastohydrodynamic lubrication is being investigated using loadsharing concept. The contacting asperities might experience elastic, elastoplastic or fully plastic contact. The engagement of pinion and gear for each point along the line of action is replaced with contact of two cylinders. The radii of these cylinders as well as the exerted load vary along the line of action. Using loadsharing concept, the proposed model can predict the lubricant film thickness, friction coefficient, and portion of the total load that is carried by asperities as well as lubricant film. The predicted results are verified by comparison to other available methods which are published in the literature.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
10
16
http://mme.modares.ac.ir/article_11171_5cafd5cf0b709eb852aaac18909fe84c.pdf
Blood pulsatile effect on LDL mass transport in a multilayered carotid artery with atherosclerotic plaques
Amin
Deyranlou
دانشجوی کارشناسی ارشد مهندسی مکانیک/ دانشگاه فردوسی مشهد
author
Hamid
Nizamand
استاد گروه مهندسی مکانیک/ دانشگاه فردوسی مشهد
author
Yaser
Mesri
دانشجوی کارشناسی ارشد مهندسی مکانیک/ دانشگاه فردوسی مشهد
author
text
article
2014
per
Lipid solutes in blood such as LowDensity Lipoproteins (LDLs) are the major cause of most cardiovascular diseases. Increase of fatty materials in the blood flow endanger personal healthiness and enhance possibility of cardio and cerebrovascular infarctions. In order to provide nutritional blood for different tissues, heart sends pulsatile flow with high pressure to the circulatory system such that LDL particles spread over the entire body. Contraction and expansion of the heart create pulsatile flow that affect blood hemodynamics and LDL mass transfer in vessels. In this paper, effects of the pulsatile flow on LDL mass transport in a multilayered artery with atherosclerotic plaques are investigated numerically. In order to apply pulsatile flow in the artery, a set of specificperson flow and pressure pulses, which are resulted from the ultrasound method, are employed directly. Results indicate that pulsatile flow increases LDL concentration both on the luminal surface and across arterial layers and produces interesting periodic concentration patterns in these regions. Moreover, pulsatile effect intensifies remarkable reversal flow right at poststenotic regions of plaques locations, where the flow is recirculated naturally, and lowers LDL accumulation.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
17
26
http://mme.modares.ac.ir/article_11142_0e13ef89524cd5d2bc0510e32b425c2b.pdf
Numerical investigation on the effect of various geometries on mixing efficiency of passive micromixers with oscillatory inlet velocities
Sima
Baheri Islami
Academic Member (Assistant professor) / University of Tabriz
author
Salman
Ahmadi
University of Tabriz
author
text
article
2014
per
Because of the low Reynolds numbers in microchannels, using of micromixers to improve the flow mixing is essential. Therefore, in this study mixing in nine different micromixer geometries, such as: simple Tshaped micromixer, micromixer with rectangular or parallelogram ribs on the walls of the mixing channel, Tshaped micromixer with two additional parallel or perpendicular inlet channels, micromixer with circular or triangular barriers in the middle of the mixing channel, rhombus micromixer with thick or thin edges, has been investigated. Sinusoidal oscillatory velocity with a phase difference of 180 degrees relative to each other has been applied to channels inlet. The governing equations have been solved numerically using the finite volume method. For all geometries time variation of mixing degree at microchannel outlet and the variation of mixing degree along the channel length have been computed. Results show that for micromixers, which divide the flow to several layers such as rhombus micromixers, mixing degree is high and the micromixers with ribs on the walls have lower mixing degrees. Also, there is an optimum frequency at constant average velocity in which the mixing degree has its highest value.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
27
34
http://mme.modares.ac.ir/article_11170_a05536c348dc8893d1b5295c53cb2dec.pdf
Detection of Size and Location of Crack in Pipes Under Fluid Pressure by Neural Networks
Mostafa
Rostaghi
دانشگاه تربیت دبیر شهید رجایی
author
Mehrdad
Khajavi
Shahid Rajaee Teacher Training University
author
text
article
2014
per
In this research crack size and location in pipes under fluid pressure will be detected using pipe’s natural frequencies by neural network. Neural network used in this research is multilayer perceptron. Comparing different inputs, appropriate inputs are selected. Pipes contain water. Steel and aluminum pipes were used in this research. Pressure condition of the pipes is: 1) without water 2) water with zero pressure 3) water with 0.498 MPa 4) water with 0.981 MPa. Crack size range from 0.19043 to 0.6346. Crack location range from 0.199 to 0.403. Many researches have been done about crack detection based on natural frequencies of structures by neural network. However, as far as authors know, no work has been done for crack detection in pipes containing pressurized water. Also in this paper two structures with different materials have been used for neural network training and testing which is another innovation of this research. Comparison of the results of this method with analytic methods shows that the proposed method is always more accurate in detecting crack size but is not always better in estimating crack location.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
35
42
http://mme.modares.ac.ir/article_11130_d47028473604e8eea55ac888f5767e71.pdf
Effects of nanoclay on the ballistic behavior of GLARE  Experimental and numerical investigation
Abbas
Masoudi
Tarbiat Modares University
author
Gholamhossein
Lighat
دانشگاه تربیت مدرس
author
Mohammad Hossein
Pol
Tafresh University
author
text
article
2014
per
This paper investigated experimentally and numerically the effect of nanoclay on ballistic impact behavior of GLARE. The prepared GlARE is made of two Aluminum 2024 facing sheets and E glass/ epoxy/nanoclay as nano composite core. Nano composite section has been composed of undirectional E glass 409 g/m2, resin CY 219, hardner HY 5161 and nanoclay closite 30B dispersed into the epoxy system in a 0%, 4%, 7% and 10% ratio in weight with respect to the matrix. All panels fabricated using laidup method in fiber weight fraction of 60%. Ballistic tests were conducted using Gas gun at the velocity of 205 and 225 m/s. The results of the ballistic impact experiments show that the amount of Specific energy absorption variations in 4% of nanoclay content is insignificant. However, in nanoclay contents of 7% and 10%, the Specific energy absorption increases. In other words, it be concluded that nanoclay has positive effect on higher percentage on the ballistic impact. The 3D finite element (FE) code, LSDYNA, is used to model and validate the experimentally obtained results. A noticeable correlation was found between experimental and numerical results.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
43
51
http://mme.modares.ac.ir/article_11140_efe060d97649b189b4826722196bea1c.pdf
Prediction a Range for Elastic Modulus of CNT Reinforced Polymer Composites using Analytical Method
Mehdi
Mondali
Assistant Professor, Mechanical & Aerospace Engineering Faculty, SRBIAU
author
Mahmoudreza
Yousefi
دانشجوی کارشناسی ارشد هوافضا
دانشگاه آزاد اسلامی واحد علوم و تحقیقات
author
text
article
2014
per
Analytical and finite element models predict the elastic modulus of CNTpolymer nanocomposites greater than experimental results. This paper presents a theoretical full continuum model to define the upper and lower thresholds with small variations for elastic modulus in polymer nanocomposites, which the experimental results always place between these thresholds. For this purpose, the governing elasticity equations in polar coordinates have been solved for nanocomposite representative volume element (RVE) with shearlag model by assuming perfect bond condition between CNT and matrix. In addition, the nanocomposite elastic modulus in perfect bond and debonding conditions between nanotube and matrix is calculated using finite element method in ANSYS software which confirms the accuracy of theoretical results. Also the obtained analytical and FEM results are compared with available experimental results, which indicates that the value of experimental results is always between the upper and lower thresholds of analytical and FEM results.finally by surveying the axial and vonmises stress in the matrix region, the new way for defining the elastic modulus of new nanocomposites with analytical method is proposed here which reduce the cost of experimental research.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
52
60
http://mme.modares.ac.ir/article_11172_c8ae09d2cd46f106720fd17a96dc8ea1.pdf
Temperature Distribution in a Hollow Cylinder Composed of Functionally Graded Material using Fractional NonFourier Single Phase Lag model
Aziz
Azimi
Assistant Professor Shahid Chamran University of Ahvaz
author
Shahab
Gholami
Shahid Chamran University of Ahvaz
author
text
article
2014
per
In this study, numerical solution of nonFourier heat conduction is discussed by a fractional single phase lag model in an inhomogeneous hollow cylinder made of a functionally graded material. For this purpose, all material properties of the media are assumed to vary continuously according to a powerlaw formulation except the phase lag and fractional order considered as constants. It is assumed that the cylinder is onedimensional, symmetric and without any heat source. The governing equation has been solved numerically in a try and error algorithm to find the phase lag and the fractional order using an implicit numerical method. In order to validate the results, the numerical solutions of the fractional single phase lag model and the dual phase lag model are compared to the results of semianalytical dualphase lag. In the following the influence of nonhomogeneity parameters is studied on the maximum transient temperature and thermal wave transmission speed. The temperature distribution is investigated from wave creation instance to steady state thermal distribution. Finally, the effect of different time delays and fraction orders on the temperature distribution is investigated.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
61
67
http://mme.modares.ac.ir/article_11205_fbba48179796b19051a331a26874bcd8.pdf
Identification of Lorenz chaotic system based on synchronization using fractional order calculus
Mehdi
Gomroki
دانشگاه صنعتی شریف
author
Mohammad
Abedini
دانشگاه صنعتی شریف
author
Hassan
Salarieh
استادیار/ دانشگاه شریف، دانشکده مکانیک
author
Ali
Meghdari
دانشگاه صنعتی شریف
author
text
article
2014
per
In this paper the goal is to identify the parameters of the Lorenz chaotic system, based on synchronization of identical systems using fractional calculus. The method which is used for synchronization is come from Lyapunov stability theorem and then by using fractional dynamics, control laws are improved. To this end, a Lyapunov function is presented and based on the Lyapunov stability theory and asymptotic stability criteria, some adaptation laws to estimate unknown parameters of the system are proposed. The introduced method is applied to the Lorenz chaotic system and since the goal is identification, all the parameters of the system are taken unknown. Using invariant set theory, it is proved that the parameter estimation errors converge to zero. Then the results of numerical simulations are shown and discussed and it is observed that fractional calculus has an essential effect on reducing fluctuations and settling time of the parameters convergence. At the end, the stability of the system by using fractional adaptation law is discussed. It is shown that the asymptotic stability of the synchronization error dynamics is proved using the fractional adaptation law, and this is confirmed through simulation.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
68
76
http://mme.modares.ac.ir/article_11215_2d3903f33a3a656f921e33c843c8e66c.pdf
Analytic Bifurcation Investigation of Cylindrical Shallow Shells under Lateral Stochastic Excitation
Alireza
Asnafi
Shiraz University
author
text
article
2014
per
In this paper, the nonlinear behavior, instability and bifurcation phenomena in the response of a cylindrical shallow shell under lateral white noise excitation are studied. The structure interacts with a general non aging viscous medium that can be modeled by relaxation or creep kernels. Using the powerful FPK equation and some practical and logical simplifications, an exact solution for such complex system including nonlinearity, viscoelasticity and randomness is obtained. Since all statistical properties of response such as mean, variance, statistical moments, central moments, etc. can be obtained from the probability density function, the behavior of this function including the number and sign of its roots and their effects on the stability, bifurcation phenomenon and the type of bifurcation is investigated and studied. In this process, using some non dimensional quantities, the governing equation and the probability density function are rearranged such that the results of simulations can be used for a broad band of cylindrical shallow shells. Finally, using some examples, the variations of the non dimensional quantities on the whole behavior, stability and bifurcation type of response are studied.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
77
84
http://mme.modares.ac.ir/article_11216_ea2017f788e6a6a062a958b92e9c1fe6.pdf
Thermodynamic analysis and optimization of a novel ejector cascade refrigeration cycle
Damoon
Aghazadeh Dokandari
کارشناس کالا  شرکت ملی نفت ایران  شرکت مناطق نفت خیز جنوب
author
Seyyed Mohammad
Seyyed Mahmoudi
عضو هیئت علمی دانشکده مکانیک دانشگاه تبریز
author
Alireza
Setayesh Hagh
عضو هیئت علمی گروه مهندسی مکانیک دانشگاه آزاد اسلامی واحد بستان آباد
author
text
article
2014
per
Throttling process through expansion valves causes a considerable amount of exergy loss so that reducing this loss improves the performance of compressed refrigeration cycle considerably. In the present work, the effect of using an ejector on the performance of a cascade refrigeration cycle is evaluated. It is concluded that the using ejector and selecting R134a as the high temperature circuit refrigerant cause the COP and second law efficiency to increase by approximately 6.5 percent as compared to the conventional cascade cycle with the same cooling capacity. In addition, several refrigerants including R717, R290, R134a, and R123 are examined to reveal the effect of refrigerant type in the high temperature circuit on the cycle performance. It is also found that, at a temperature of more than 255.4 K, for the evaporator of high temperature circuit, the refrigerant combination of R744R123 results in a better performance as compared to the other combinations. Finally, the cycle performance is optimized with respect to the temperatures of low temperature evaporator, high temperature evaporator, and the ambient from the view points of both the first and second laws of thermodynamics. It is concluded that the COP and the second law efficiency are the highest when R123 is used as the refrigerant at the high temperature circuit.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
85
93
http://mme.modares.ac.ir/article_11217_20b65c997f7294237220e21f1b18af48.pdf
Experimental investigation of the effect of hillyterrain duct on gasliquid flow
mohammad
ansari
استاد/دانشگاه تربیت مدرس
author
mohammad
Ahmadi Ghiri
دانشجوی دانشگاه تربیت مدرس
author
behzad
sadeghi hajipirloo
دانشجو/دانشگاه تربیت مدرس
author
text
article
2014
per
This study is an experimental investigation of twophase waterair flow in hillyterrain duct.The inclination angles for hill and valley configuration is ±7.5o. Review of the related literature showstheir results are limited to slug regime only. In the present study, flow regime map and pressure traces are investigated. This study reveals that the possible slug flow behavior categories exist along a valley and hill configuration are four and two, respectively. In an attempt to relate the qualitative flow behavior at a valley and hill to the flow pattern maps of upstream and downstream, this qualitative classification is superimposed on flow pattern maps where obtained independently for the upstream and downstream sections. The results show, flow has different behavior in hill in compare to valley at relatively low gas flow rates. However, at higher gas velocity, difference between hill and valley behavior decreases.It can be concluded, that the effect of hill and valley behavior are similar on flow regime at relatively high gas flow rates.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
94
102
http://mme.modares.ac.ir/article_11239_bfe0ca5450a610adb02a9392e8ae2819.pdf
Investigation of the tensile and the flexural properties of the glass/epoxy composites reinforced with nanoclay particles
Mohammad
Pol
استادیار دانشگاه تفرش
author
Seyed Abdoelvahab
Hoseini
هیات علمی دانشگاه آزاد واحد شوشتر
author
text
article
2014
per
In this paper, the influence of nanoclay Closite 30B on the tensile and the bending properties of 2D woven E Glass/Epoxy laminated composite have been investigated experimentally. The glass/epoxy/nanoclay laminate have 12 layers and 60% fiber volume fractionis is manufactured by VRTM method. Fibers have a plainweave configuration with density of 200 gr/m2, while the nanoepoxy resin system is made of diglycidyl ether of bisphenol A (epon 828) resin with jeffamine D400 as the curing agent and an organically modified MMT in a platelet form, namely Closite 30B. The nanoclay is dispersed into the epoxy system in a 0%, 3%, 5%, 7% and 7% ratio in weight with respect to the nanomatrix. The results have shown that Maximum to increase in the tensile and the bending properties are in 3% and 10% nanoclay content. The maximum to increase in the tensile strength, the failure strain and toughness are 13%, 7% and 27% respectively in 7% nanoclay content and in the modulus is 9% in 3% nanoclay content. Moreover, the maximum to increase in the flexural strength is 11% in 3% nanoclay content and in flexural modulus is 48% in 5% nanoclay content.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
103
108
http://mme.modares.ac.ir/article_11237_d7ca795ee41336425e7fbdd61fd315cf.pdf
Experimental Investigation of Forced Convection of Nanofluids in a Horizontal Tube Filled with Porous medium
Mohsen
Nazari
Assistant Prof. of Mechanical Eng.
Shahrood Univ. of Technology
author
Mojtaba
Ashouri
دانشگاه شاهرود
author
mohammad Hasan
Kayhani
دانشگاه شاهرود.
author
text
article
2014
per
Heat transfer of Alumina/water nanofluids in a uniformtemperature porous pipe has been investigated in a wide range of Reynolds number, i.e. 700<Re<5000. Investigation of force convective heat transfer of nanofluids in a porous pipe with uniform wall temperature has not been considered completely in the literature. In this experimental study, Alumina nanofluids with different volume fractions have been completely employed. By measuring the nanofluid temperatures, the Nusslet numbers have been reported as a function of the Reynolds number. Also, the pressure drop of nanofluids inside the porous pipe has been measured. The accuracy of the experimental results has been also validated by the presented theoretical formulas in the literature. The result shows a considerable increase in the Nusslet number by using nanofluids instead of water. Convective heat transfer of a porous pipe has been also studied as a novel method to increase the heat transfer rate. The related results show a significant increase in the heat transfer in the presence of porous medium. Both heat transfer and pressure drop of nanofluids in the porous pipe have been also reported and discussed.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
109
116
http://mme.modares.ac.ir/article_11244_e3ba9d32534be962047c86dbe0fa687d.pdf
Application of a Simple Robust 2D PictorialGeometrical Feature on QRS Complex Detection
Amir
Hoseini Sabzevari
دانشگاه فردوسی مشهددانشکده مهندسیگروه مکانیک
author
Majid
Moavenian
دانشگاه فردوسی مشهددانشکده مهندسیگروه مکانیک
author
text
article
2014
per
In this paper a heuristic method, called Moving Window KNearest Neighbors (MWKNN), for detecting QRS complexes was developed. To achieve this, a new simple 2D geometrical feature space (feature space dimension was equal to 2) was extracted from the original electrocardiogram (ECG) signal. In this method, a sliding window was moved samplebysample on the preprocessed ECG signal. During each forward sliding, an artificial image was generated from the excerpted segment allocated in the window. Each image estimated by a 300×300 pixels matrix. Then, a pictorialgeometrical feature extraction technique based on curvelength was applied to each image for establishment of an appropriate feature space. Afterwards the KNearest Neighbors (KNN) Classification method was designed and implemented to the ECG signal. The proposed methods were applied to DAY general hospital high resolution holter data. For detection of QRS complex the average values of sensitivity Se = 99.93% and positive predictivity P+ = 99.88% were obtained.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
117
121
http://mme.modares.ac.ir/article_11240_b409fa43de06fdac79b629bdd8a9bd27.pdf
Exact solutions for free vibration of lévytype rectangular nanoplates via nonlocal thirdorder plate theory
Reza
Nazemnezhad
دانشجوی دکتری / دانشکده مهندسی مکانیک دانشگاه علم و صنعت ایران
author
shahrokh
Hosseini Hashemi
Iran university of science and technology/professor
author
Mehdi
Kermajani
کارشناسی ارشد / دانشکده مهندسی مکانیک دانشگاه علم و صنعت ایران
author
Shahram
Amirabdollahian
کارشناسی ارشد / باشگاه پژوهشگران جوان، دانشگاه آزاد اسلامی سمنان
author
text
article
2014
per
In this paper, exact closedform solutions in explicit forms are presented to investigate small scale effects on the transverse vibration behavior of Lévytype rectangular nanoplates based on the Reddy’s nonlocal thirdorder shear deformation plate theory. Two other edges may be restrained by different combinations of free, simply supported, or clamped boundary conditions. Hamilton’s principle is used to derive the nonlocal equations of motion and natural boundary conditions of the nanoplate. Two comparison studies with analytical and numerical techniques reported in literature are carried out to demonstrate the high accuracy of the present new formulation. Comprehensive benchmark results with considering the small scale effects on frequency ratios and nondimensional fundamental natural frequencies of rectangular nanoplates with different combinations of boundary conditions are tabulated for various values of nonlocal parameters, aspect ratios and thickness to length ratios. Due to the inherent features of the present exact closedform solution, the present findings will be a useful benchmark for evaluating the accuracy of other analytical and numerical methods, which will be developed by researchers in the future. Also, the present study may be useful for static and dynamic analysis of thicker nano scale platelike structures, multilayer graphene and graphite as composite or sandwich structures.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
122
130
http://mme.modares.ac.ir/article_11241_ce152caab3558640117935290bb7e517.pdf
Free vibration analysis of bilayer graphenes with interlayer shear effect
Reza
Nazemnezhad
دانشجوی دکتری مهندسی مکانیک / دانشگاه علم و صنعت ایران
author
shahrokh
Hosseini Hashemi
Iran university of science and technology/professor
author
Hassan
Shokrollahi
دانشجوی دکتری مهندسی مکانیک / دانشگاه صنعتی شریف
author
text
article
2014
per
In this paper, for the free vibration analysis of bilayer graphenes with interlayer shear effect the sandwich beam model is introduced. Because of the similarity between the bilayer graphene and the sandwich structures, in which at the top and the bottom of the bilayer graphene there is a single layer graphene and between them there is Vander walls bindings, the bilayer graphene is modeled as a sandwich beam and its free vibration is investigated for freeclamp end condition. To obtain the governing equations, each graphene layer is modeled based on the EulerBernoulli theory and inplane displacements are also considered in addition to the transverse displacement. It is also assumed that the graphene layers do not have relative displacement during vibration. The effect of the Vander walls bindings is introduced in the governing equations as the shear modulus. The results obtained by the sandwich beam model, presented in this paper for the first time, include the first five natural frequencies of the bilayer graphenes with 7 to 20 nanometer lengths. These results are validated by the molecular dynamic and the MultiBeamShear model results.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
131
138
http://mme.modares.ac.ir/article_11242_837fe96fabcfea1b8369de96b38d9eda.pdf
Analysis of mode III in infinite plane with multiple cracks based on strain gradient elasticity
Iman
Karimipour
دانشگاه یزد
author
Ali Reza
Fotuhi
دانشگاه یزد
author
text
article
2014
per
In this paper, the antiplane stress analysis in an infinite elastic plane with multiple cracks is carried out by using the distributed dislocation technique. The solution is obtained for an infinite plane containing the screw dislocation via Fourier transform of biharmonic equation for the analysis of infinite plane in gradient elasticity. These solutions are used to perform integral equations for an infinite plane weakened by multiple straight cracks. Integral equations are hypersingular type which are solved numerically for density of dislocation on the cracks surfaces. The numerical method in Chebyshev series form are used to solve the hypersingular integral equations. The solution of integral equations leads to dislocation density functions. The stress intensity factor for cracks tips are formulated in terms of density of dislocation. Employing the definition of dislocation density, stress intensity factors for cracks tips are calculated. The influence of sizeeffect and crack location on the stress intensity factors are studied. To confirm the validity of formulations, numerical values of stress intensity factors are compared with the results in the literature. The results of the present approach are in excellent agreement with those in the literature. Some new examples with different geometrics of cracks are solved to illustrate the applicability of procedure.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
139
149
http://mme.modares.ac.ir/article_11243_37ebe38fc60ae37e719b2c583950b1b4.pdf
Application of corotational method in geometrical nonlinear analysis of tensegrity structure and effect of prestress
Asad
Ghafori
instructor of Islamic Azad uni. Sanandaj baranch
author
Shirko
Faroughi
استادیار دانشگاه صنعتی ارومیه
author
Mehdi
Bamdad
استادیار دانشگاه صنعتی شاهرود
author
text
article
2014
per
Tensegrities are a kind of spatial structural system composed of cable (in tension) and strut (in compression). Stability of this system is provided by the self stress state between tensioned and compressed elements. In this paper, corotational method is used for study geometrical nonlinear analysis of tensegrity structure and analysis of the effect of prestress on it. This approach unlike other available approach in nonlinear static analysis, the major part of geometric nonlinearity is treated by a corotational filter. The function of CR formulation is to extract relevant deformation quantities free or almost free from any rigid body motion in a given displacement field. One of advantage of the corotational approach is the fact that linear models can be easily used in the local coordinate system for modeling of nonlinear problems. The geometric nonlinearity is incorporated in the transformation matrices relating local and global internal force vectors and tangent stiffness matrices. Three different numerical examples are studied using this approach. Results demonstrate that the deformations of tensegrity system are dependent on the value of prestress in tensegrity systems. The displacements of tensegrity system are decreased for fixed external tensile loading and increasing pretension force, however, for fixed pretension force and increasing external loading the displacements of tensegrity system are increased.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
150
156
http://mme.modares.ac.ir/article_11250_1614c2030f08d4de002bb4ef66bbdd53.pdf
Soft Sensor Design for Fault Detection in ALV Pitch Gyro
mehdi
hasani najafabadi
دانشکده هوافضا دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Jafar
Roshanian
عضو هیوت علمیدانشکده هوافضا دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Abdolmajid
Khoshnood
عضو هیئت علمیدانشکده هوافضا دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Habib
Khaksary
دانشکده هوافضا دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Hadi
Tekieh
دانشکده هوافضادانشگاه خواجه نصیر
author
text
article
2014
per
Aerospace Launch Vehicles (ALVs), used for launching artificial satellites and space stations to Earth orbits, usually encounter with failure in navigation systems . In these cases, survival of an ALV during accurate payloads injection in orbits is one of the most critical issues for Guidance and Control systems.An important challenge for safety of Aerospace Launch Vehicle (ALV) is their reliability against all types of faults. There is a requirement for onboard fault detection without deteriorating the performance of ALV. In this paper, a new software sensor is proposed for fault detection and compensation based on symmetrical behavior of the yaw and pitch channels of an ALV. For this purpose, using identification techniques on the yaw channel, a new software sensor is developed as an online rigid dynamic predictor for the pitch channel. The proposed software sensor is employed to generate the residual of estimation error as an indicator of predefined faults. The main novelty of this software sensor is online tuning of the virtual sensor against unforeseen variations in the parameters of the vehicle. Robustness of the new control system in the presence of asymmetric behavior is investigated. The efficiency of the proposed fault tolerant method is illustrated through simulations.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
157
162
http://mme.modares.ac.ir/article_11248_c0e1e71911c66d636b8016789991876c.pdf
Experimental study on the effect of coal particles injection on flame structure, radiation heat transfer, temperature distribution and thermal efficiency in natural gas diffusion flames
Mohammad
Moghiman
ferdowsi university of mashhad department of mechanical engineering
author
Seyed Hadi
Poorhoseini
Ferdowsi university of mashhad, department of mechanical engineering
author
text
article
2014
per
Using natural gas as a clean fuel is raising. In many industrial combustion systems, like industrial furnace and boilers, a large portion of heat transfer is done by radiation and using natural gas in these industrial systems leads to decrease in radiation heat transfer that faces the Manufacturers with many problems. The addition of solid reactant particles into the flame is one of the attractive methods that are considered by many researchers to increase the radiation heat transfer in nonluminous flame such as hydrogen and natural gas flame. In this study, the effect of coal particles injection into the natural gas diffusion flame on flame structure, radiation heat transfer, temperature profile, and thermal efficiency has been considered. The results show that the injection of coal particles into the natural gas by increasing the solid soot particles in the flame structure, increases the reaction surface and flame luminosity and with increasing the radiation emissivity coefficient, increases the radiation heat transfer and thermal efficiency 43% and 21% respectively. Whereas change in flame temperature is very low and is 47˚C in its extreme limit.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
163
168
http://mme.modares.ac.ir/article_11249_dbb8df573979112271d8e2f3159368b6.pdf
Performance investigation of control and guidance system
for a spinning flight vehicle with dithering canard
mojtaba
mirzaei
دانشگاه شیراز
author
Mohammad Mahdi
Alishahi
دانشگاه شیراز
author
text
article
2014
per
In this paper, control and guidance system of a spinning flight vehicle with a single plane of dithering canard control fins are investigated. Decreasing the number of actuators, lowering the vehicle weight, and reducing the final cost are outcomes of applying two canard controls; however, the control system will become complicated due to guidance system interaction. Producing asymmetric force and torque in yaw direction is the result of this interaction. Dithering canard is proposed for proper control of this spinning vehicle. Dithering canard adjusts its deflection with respect to the roll attitude of the flight vehicle. In this paper, a method is proposed for control and guidance of this spinning vehicle with dithering canard. This method is investigated in a six DOF flight simulation in presence of IR seeker, autopilot, gyro, actuators. Appropriate simulation results in various flight situations verify the proper performance of this new control method.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
169
175
http://mme.modares.ac.ir/article_11251_f53f160fa19870b4e261abca3377de56.pdf
Three Dimensional Simulation of TwoPhase Slug Flow Regime In a Horizontal Channel Using VOF Method
mohamadreza
ansari

author
Ebrahim
Salimi
دانشگاه تربیت مدرس
author
Babak
Habibpour
دانشجوی کارشناسی ارشد
author
Pouyan
Adibi
دانشجوی دکترا
author
text
article
2014
per
In this article, twophase slug flow is simulated numerically in a horizontal duct with rectangular crosssection using Volume Of Fluid (VOF) method. Conservation equations of mass, momentum and advection equation are solved in open source OpenFOAM code accompanying kω SST turbulence equations. Simulation is conducted based on the experimental results in the duct with rectangular crosssection. The results shows, due to KelvinHelmholtz (KH) instability criteria slug initiation forms in the airwater interface during three dimensional turbulence modeling. Water level was increased slightly at interface in both numerical simulation and experiment. This level increase satisfies the KH instability to generate a slug at interface. During slug initiation, the pressure behind slug is increased significantly. Big pressure gradient at the beginning of the slug in compare to the end of it causes the slug length to be increased as propagate along the duct. The numerical simulation of present research is capable of predicting the slug length accurately in accordance with experiment; however, the slug position with 22% inaccuracy was obtained. Comparison of the results with the numerical and experimental results of other researchers confirms higher accuracy of flow prediction in the present work.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
176
182
http://mme.modares.ac.ir/article_11252_01219b9904694e8fa9800756fbfb52dd.pdf
Investigation of microstructure and mechanical behavior of Woodlouse shells using experimental methods and numerical simulation
Abolfazl
Darvizeh
عضو هیئت علمی/دانشگاه گیلان
author
Sara
Anami Rad
دانشگاه گیلان
author
Mansoor
Darvizeh
دانشگاه گیلان
author
Reza
Ansari
دانشگاه گیلان
author
Hamed
Rajabi
معاون گروه مکانیکموسسه آموزش عالی احرار
author
text
article
2014
per
In this paper, a scanning electron microscope (SEM) is used for microstructural investigations of a woodlouse shell. Finite element (FE) method is employed to study the dynamic behavior of the shell subjected to the impact of a coneshaped projectile. Despite of small thickness, the shell, as a composite material, enables the insect to bear large external forces. The woodlouse is also able to roll up into a complete sphere to protect itself from danger. In order to study this defense mechanism, the external loads are applied to the shell in different configurations: when the shell is in (1) normal and (2) rolledup forms. The simulations are performed at different velocities and at different impact angles. Comparisons of the results obtained from different simulations indicate that the defense mechanism of the woodlouse has an important role in decreasing the stress concentrations. Indeed, it is a defense mechanism which effectively increases the loadbearing capacity of the insect shell. The results of the present research may be useful in the design and manufacture of modern engineering structures with a high strength to weight ratio.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
183
190
http://mme.modares.ac.ir/article_11253_64101e2669604a977d83766eda3c5ffc.pdf
Residual Generation in Linear Systems with Unmatched Uncertainties for Fault Detection Problems
Esmaeel
Bagherpour A.
دانشجو
author
MohammadReza
HairiYazdi
عضو هیئت علمی دانشگاه تهران
author
Mohammad
Mahjoub
عضو هیئت علمی دانشگاه تهران
author
text
article
2014
per
This paper deals with the design of an unknown input observer (UIO) with the assumption that the wellknown observer matching condition is not satisfied. The proposed method can be used for fault detection problems with the use of residual vector. The basis of method is to compensate the unmatched uncertainties with the use of a set of auxiliary outputs. The introduced auxiliary outputs are obtained from successive integration of the system measurements and known inputs. Then, an unknown input observer is proposed which estimates exponentially the outputs. Therefore, the residual vector, generated from the estimated outputs and the actual outputs, will be obtained which insensitive to the unmatched disturbances. At the same time, the sensitivity of the proposed residual vector to the fault in sensors is investigated. The generated residual vector will be more robust against the presence of noise in the measurements. It is shown through numerical simulations that the proposed residual vector is sensitive to the presence of fault in sensors while it is insensitive to the presence of the unknown input. In addition, a comparison with a derivative based method is presented.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
14
v.
7
no.
2014
191
198
http://mme.modares.ac.ir/article_11264_39159da679d48b2454de3f40acd5c62b.pdf