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This article was developed on the base of the findings of a research named “Designing a public policy making system to achieve social justice, based on Alavian truth-oriented model of governance” (2004). Every public policy making system is usually designed based on a set of principles and fundamental statements; the principles that are impacted from dominant doctrines of political philosophy schools in their social environment. Usually these doctrines are formulated by ideological challenges, ethical discourses or reasonable consensus. But, to conceptualize the truth oriented justice, it is important to regard logical analytical method for referring and formulating the statements to establish a reliable knowledge based system. So, applying comparative analysis and logical analytical method will help the transaction from truth-directed system to truth-oriented system. In this method, after introduction and acceptance of a set of reasonable principles, several theorems were extract. (These principles were extracted from Nahjolballagha but were formulated based on logical analytical method); and the final logical system was made based on these principles and theorems. Accordingly, we can benchmark these statements as one of the best systems for assessing the doctrines of other systems. In this way, the universal declaration of human rights, as a best verbal artifacts of human being, was compared with this system, using a comparative approach. Finally, the valuable results of the truth-oriented system were emphasized.

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Electrostatic motors are presented special advantages compare to electromagnetic motors such as light-weight, compactness and simple to fabricating. Due to these capabilities, recently, many researchers are working on electrostatic motors to make them applicable in industries. Accordingly, in this paper a new design idea for these motors is investigated theoretically and experimentally. This motor has driving electrodes on both rotor and stator, however, no wire is attached to rotor and signals are transferred to rotor using the induction electrodes. Modeling is implemented to study the effective parameters on performance. Then, using the modeling results, the design parameters are optimized using numerical method to improve the torque and minimize the ripple. Optimization findings are identified an optimum value for ratio of width to gap for driving electrodes and an optimum value for ratio of induction electrodes surface to total surface. Finally, the motor performance is evaluated using experimental setup and several experiments.

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Dams as one of the most important structures are always exposed to various hazards such as earthquake. As dam failure may lead to financial damages and fatalities, it should be designed with most economical and accurate methods. An earthquake causes hydrodynamic pressure waves exerting on the dam. This is one of the important factors in design of dams that are always considered by consulting engineers. Helmholtz equation is the governing relation on the propagation of hydrodynamic pressure waves in dam reservoirs during an earthquake. In order to solve the Helmholtz equation to calculate hydrodynamic pressures on dams, the reservoir’s boundary conditions (BCs) should be taken exactly into account. The BCs include (a) the interface boundary of dam and reservoir (as initial zone of reservoir excitation), (b) bottom boundary (with partial absorption of wave energy by accumulated sediments), (c) upstream boundary (with radiation of another part of the wave energy from the reservoir), and (d) formation of surface waves in the upper boundary of the reservoir. The purpose of present study is to model the mentioned physical phenomena in the frequency domain, using a new semi-analytical method, called Decoupled Equations Method (DEM). In the DEM, only the domain boundaries are discretized by specific high-order non-isoparametric elements. The main features used for modeling of geometry and physics of the problem consists of: (1) high-order Chebyshev polynomials as mapping functions, (2) special shape functions of 2n_η+1 degree polynomials for (n_η+1)-node elements , (3) Clenshaw-Curtis quadrature, and (4) integral forms produced by weighted residual method. By using these features and their properties, coefficient matrices of the system of governing equations become diagonal. This means that the governing partial differential equation for each degree of freedom (DOF) becomes independent from other DOFs of the domain to be analyzed. Therefore, this reduction in space dimensions of the main problem may significantly reduce computational costs in comparison with other available numerical methods. In this study, for the first time in order to provide a solution by low costs to calculate the hydrodynamic pressure distribution on the gravity dams, the relations of reservoir’s BCs are derived in local coordinates by using of the DEM and, the process of applying derived equations is then expressed into the solution of Helmholtz equation. To verify this method, an example of this field is solved by using the DEM, where dam and its rigid foundation are excited by horizontal harmonic vibration. The obtained responses from the solution of this example indicates that the present method for modeling of the potential problems with natural boundary conditions under earthquake excitations, by considering propagation of hydrodynamic waves in the reservoir, show acceptable accuracy and feasibility in comparison with the available analytical solution. The results of the DEM should be developed for more general condition of dam-reservoir interaction, which include flexible concrete gravity dams with inclined dam-reservoir interaction boundary conditions along with partial absorption of wave energy by accumulated sediments. These features are being followed by the authors, and will be disseminated in new papers soon.

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In this study, by modeling van der Waals (vdWs) interactions based on the Lennard-Jones potential function interlayer tensile-compressive and shear moduli of bilayer graphene sheets are analytically calculated. To this end, by varying potential depth parameter which shows the strength of vdWs interactions a new model is presented for calculating interlayer in-plane and out-of-plane moduli for two different stacking patterns. In order to determine the interlayer vdWs moduli, a small flake of monolayer graphene is sliding on a large monolayer graphene substrate and accordingly variations of vdWs forces as well as the interlayer shear and normal strains are recorded. The relative displacements of layers cause linear strain and stress. In the model, bilayer graphene geometry (being armchair or zigzag, and stacking pattern) and potential depth parameter are two important parameters for determination of vdWs moduli. The accuracy of the method is verified by comparing the present results with those reported in literatures. Finally, close-form relations for interlayer tensile-compressive and shear moduli of vdWs interactions versus the depth potential parameter are presented for ABA and AAA stacking patterns as well as zigzag and armchair directions. It is observed that the interlayer moduli have linear relation with the potential depth parameter.

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Due to high strength and stiffness-to-weight ratio of composite cylindrical shells, they are increasingly being used in different industries. Applying different types of stiffeners is one of the ways to improve the buckling resistance of these structures. In this paper new analytical method based on smear method is developed to analyze the stiffened composite shells. The main difference of this method and previous methods is on technique of combination of shell`s and stiffeners` stiffness parameters, and calculating the equivalent stiffness parameters. In the suggested method a three layered shell is designed in such a way that this shell and stiffeners have the same volume and stiffness. Putting these layers under the main layers of shell, the equivalent stiffness parameters could be calculated easily. Using the Ritz energy method the critical load of axial buckling of shell is calculated. The method is verified using finite element ABAQUS package. The results show that the proposed method has less difference from finite element`s results compare to previous methods. In addition, the effects of different parameters on buckling load and special buckling load of stiffened shell is investigated. The results show that in order to have efficient stiffened structure; there must be an adequate number of ribs and unit cells. It also shows that, although adding stiffening ribs increase the buckling load of the shell, the special buckling load does not increase necessarily. The optimum angle for helical ribs is 30 to 40 degrees respect to axis of the cylindrical shell.

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Shape sensitivity analysis of finite element models is useful for structural optimization and design modifications. Within numerical design optimization, semi-analytical method for sensitivity analysis is frequently applied to estimate the derivative of an objective function with respect to the design variables. Generally numerical sensitivity analysis widely suffers from severe error due to the perturbation size and find a method which is not sensitive to the perturbation size is topics under study. Complex variable methods for sensitivity analysis have some potential advantages over other methods. For first order sensitivities using the complex variable method, the implementation is straightforward, only requiring a perturbation of the finite element mesh along the imaginary axis. This paper uses a complex variable and combine it with discrete sensitivity analysis, thus present new method to obtain derivatives for linear structure. The advantage of this method are quickly, accuracy and its simple implementation. The methodologies are demonstrated using two dimensional finite element models of linear elasticity problems with known analytical solutions. Obtained sensitivity derivatives are compared to the exact solution and also finite difference solutions and show that the proposed method is effective and can predict the stable and accurate sensitivity results.

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One of the designers concerns is structural failure as a result of stress concentration in the geometrical discontinuities. Stress concentration factor in the presence of cutout, is a key parameter in reducing the structural load-bearing capacity. In the analysis of perforated isotropic plates, the effective parameters on stress distribution around cutouts are the cutout geometry, curvature radius of cutout corner, rotation angle of cutout and load angle. In this study, using PSO method it has been tried to introduce the optimum parameters to achieve the minimum amount of stress around the n-sided cutouts in isotropic plates under uniaxial tension. In this paper, an analytical method has been used to calculate the stress around cutouts with different shapes. According to this method, by using the conformal mapping, Muskhelishvili’s complex variable method which is only for circular and elliptical cutouts, has been developed for the other cutouts. The results presented in this case shows that by choosing the appropriate shape of cutout and the optimal effective parameters, stress concentration factor can be significantly reduced and lowest stress concentration factor rather than amount of stress concentration corresponding to circular hole can be achieved.

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In this article, the free and forced convectional heat transfer in a rectangular porous fin with considering pressure loss across the fin length is investigated analytically. A well-known Differential transformation method is employed to obtain the solution of energy balance equation. Convergence of obtained solution is examined by previous works and they are found to be in a good agreement. In order to simulate heat transfer through porous media, Darcy model is applied. Also convective heat transfer coefficient is assumed to be constant. Dimensionless temperature distribution is defined as a function of convection and porosity parameters. Also the effects of pressure loss across the fin length on the temperature distribution, rate of heat transfer, fin efficiency and effectiveness of fin are studied. A comparative study is also made between the porous and solid fins for an equal mass of fins. It is highlighted that the porous fin transfer always more heat at specific condition compared to the solid fin. Results show that all of thermal parameters are influenced by pressure loss parameter. So in order to reach to high fin efficiency, pressure loss across the fin length should be controlled.

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In this paper, vortex induced vibration of simply supported viscoelastic beam were investigated using semi-analytical method. By applying the general form of the viscoelastic model, the nonlinear partial differential equations of motion based on the Euler Bernoulli beam’s theory and displacement coupling fluid-structure interaction model were obtained via the Newton’s second law. A classical nonlinear van der Pol equation was taken as the governing equation for one component of the vortex shedding force on the beam. Employing the Galerkin discretization method, the equations of motion are reduced to a set of nonlinear ordinary differential equations with coupled terms and then there have been solved numerically by Runge-Kutta method. Finally, the effect of system parameters on the time response, phase plane and maximum amplitude of the beam are investigated. The results indicate that the viscoelastic behavior have a significant influence on the dynamic characteristics of the system and causes to change the Lock-in phenomenon with respect to corresponding elastic system. For example, for E2=10E1 the viscoelastic behavior can change the position of the locking area, and the maximum amplitude of the beam is increased by 45%. Lock-in from of vortex-induced vibrations was considered as a possible source of increased fatigue and damage. Therefore, by using viscoelastic materials the maximum amplitude of the system is reduced and the Lock-in condition can be changed. Additionally, based on the significant influence of viscoelastic behavior on the dynamic characteristics of the system, viscoelastic behavior should be considered in the mathematical model of the systems.

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The semi-analytical method (SAM) is an approach that computationally efficient and easy to implement. That's why this method often used for the sensitivity analysis of finite element models. However, SAM is not without defect especially in problems that rigid body motions are relatively large reveals severe inaccuracy. Such errors outcome from the pseudo load vector calculated by differentiation using the finite difference method. In the present paper, a new semi-analytical approach based on complex variables is proposed to compute the sensitivity of nonlinear finite element models. This method combines the complex variable method with the discrete sensitivity analysis to obtain the response sensitivity accurately and efficiently. The current approach maintains the computational efficiency of the semi-analytical method with higher accuracy. In addition, the current approach is insensitive to the choice of step size, a feature that simplifies its use in practical problems. The method can be used to nonlinear finite elements only requires minor modifications to existing finite element codes. In this paper, the authors demonstrate that the discrete sensitivity analysis and the complex variable method are equivalent and solve the same equation. Finally, the accuracy of the method is investigated through the various numerical examples by comparing by other methods and will show that this method is reliable and independent of step size.

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Using proper dimensionless coefficients that are insensitive to various operating conditions is a crucial issue during the utilization of a yawmeter probe. These dimensionless coefficients produce the deviation angle of flow, stagnation and static pressures. In the current study, these coefficients are analyzed using SPM analytical and experimental methods. A comparison of experimental and analytical results shows that SPM analytical method predicts the flow deviation coefficients satisfactorily at the operational angle range of three-hole probe. This method also calculates the stagnation pressure coefficient precisely at the deviation angle range of ±10 degrees. The experimental results show that due to the assumption of constant speed on the probe, the analytical method cannot calculate the static pressure accurately. Experimental observations also demonstrate that velocity is increased and pressure is decreased over the probe. This is due to the suction region at the downstream of probe. Unlike analytical results, experimental observations depict that at zero degrees, the flow static pressure is equal to the average of pressure at the left and the right side of probe. Due to sensitivity of dimensionless coefficients of flow static pressure to variation of Reynolds number, various values are reported at different kinds of literature for these coefficients. These coefficients change with Reynolds number variations and their accuracies are decreased. In the current study, a new proper dimensionless coefficient is introduced which represents minimum sensitivity to Reynolds number.

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Advancements in tunnelling technologies and ease of implementation of drilling methods in addition of other political and security issues made the construction of underground structures as an important alternative for answering the demands of population growth and the limitations of surface spaces in urban areas. Underground roads and highways, various types of tunnels and urban subway networks are the examples of underground structures being constructed and rapidly implemented in different countries. Meanwhile, for reducing negative effects to the environment, shortening the routes and improving traffic efficiency, urban tunnels should have high level of safety standards in design, construction and operation. Tunnels are considered major national projects and infrastructure investments, and huge costs are incurred around the world to build these structures. In countries located in highly active seismic zone, such as Iran, seismic researches for such important underground structures should not be ignored. The safety of such structures should be provided with respect to all loading demands and hazards issues associated with the site, including seismic loads. Reviewing seismic events in the past shows that underground structures have suffered less damage than above ground structures against seismic loads. However, in recent years, major earthquakes such as the 1995 Kobe earthquake in Japan, the 1999 Chi-Chi earthquake in Taiwan, the 1999 Kocaeli earthquake in Turkey, and the 2008 Wenchuan earthquake in China have caused underground structures to experience significant damage. There is evidence to conclude that the structural vulnerability of a tunnel in seismically active areas is an important issue but is either not yet well understood or not well assessed at the time of construction, emphasising that dynamic analysis of these structures against seismic loads is necessary. Earthquakes are likely to significantly affect tunnel performance by causing severe damage or excessive deformation of the tunnel structure. To understand the seismic-induced behaviour and performance of urban tunnels, this paper provides the state of the art in modelling studies of seismic design and assessment of tunnels. The review includes an investigation in seismic responses of real tunnels reported during past seismic events, the probable mechanisms caused damages in tunnels and physical and numerical methods used until now to either investigate those mechanisms or implemented in new designs. As an introduction, the seismic performance of tunnels affected by previous seismic events discusses first, emphasising the effective parameters in evaluation of tunnel seismic response and the relationship between the parameters, and the damage levels caused during earthquakes. Subsequently, the paper continues with a comprehensive literature review on the experimental methods used to investigate seismic-induced response in tunnels including physical testing, centrifuge tests, shaking table tests, and static tests. Analytical, quasi-static and numerical methods of dynamic analysis of tunnels and the accuracy of these methods are discussed then in details referring to some examples. The paper also reviews the effects of soil heterogeneity in the seismic response of tunnel and application of the random field for dynamic analysis of underground structures.  Examining the achievements and challenges remained in the field, the paper concludes with the existing gaps in the field to stimulate readers for doing more relevant researches.

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Calculating the failure probability of structural problems with linear boundary condition functions is usually done at a low level and by first-order methods due to simple concepts and the need for few calculations. These methods are only suitable for providing an estimate of the probability of structural failure, and especially when the function expressing the performance of the structure is linear, they are accurate in providing the final answer. But when the limit function is nonlinear, due to inherent problems in this method, they are unable to accurately estimate the safety level of the structure. For such problems, it is necessary to use accurate methods of estimating the probability of failure, such as simulation
methods. The use of concepts in the first and second order methods of reliability along with the use of an optimization algorithm will reduce the volume of calculations, but this factor causes assumptions and simplifications, derivation of functions and estimating the sensitivity of failure probability is also a part of the structure design process. It can be proven that for many design problems with nonlinear boundary condition function, the answer provided by these methods will not satisfy the probabilistic constraints of the problem, or the answer provided is not the most economical design option. Also, many existing
methods in this group are unable to provide answers for problems with low failure probability, especially when the variables of the problem have non-normal density functions. Therefore, the present study has investigated the performance of these methods in dealing with various structural problems, and the strengths and weaknesses of each method are discussed. Three different issues have been studied in this research with seven analytical and simulation method, to achieve this goal. The first problem is to verify the results. In this case, the failure probability of a reinforced concrete beam was calculated by the Monte Carlo Simulation (MCS) and compared with the results obtained from the precise gradient method used in previous studies. The results of this problem showed a 0.5% error in the results, indicating the accuracy of the responses. The existence of very small differences between the results obtained from Monte Carlo and the results of previous researchers in estimating the integral of failure probability related to the discussed problems, indicates the high accuracy of the Monte Carlo method, and it is possible to use the results obtained from Monte Carlo as a suitable criterion in the analysis of these problems. used to compare the results. Also, analysis of two problems including three-span steel beam, two-degree-of-freedom seismic system using seven methods including MCS, SS, IS, LS, WSM, FORM and SORM were also put on the agenda. The results indicate that SS has high accuracy in solving nonlinear and complex problems. WSM has shown a significant decrease in the number of function calls. The LS method has a great performance in calculating the reliability of problems with a low failure probability. Therefore, in general, it can be stated that the first-order method (FORM) is the simplest safety estimation method (with low accuracy for non-linear functions) and simulation methods are the most accurate methods (with conceptual complexity or high calculations).

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Human civilizations have always depended on freshwater to form, develop and fulfillment of various needs. With increasing urbanization, not only has the need for freshwater not diminished, but also some new technologies and industries have increased water consumption, and the pollution of water sources has increased significantly. Since groundwater resources are far from surface pollution and have their natural remediation ability, protection and remediation have not been given sufficient and appropriate attention. This issue and the overexploitation of aquifers have resulted in the quantitative and qualitative balance of groundwater resources being unsustainable. These issues show that further research is needed on various aspects of groundwater remediation. By developing the equations for water movement in porous media and analyzing them, it is possible to simulate groundwater flow. In this study, the double-well pumping system has been investigated analytically as one of the effective methods for aquifer remediation. In this system, pumping wells provide a return to natural conditions by draining polluted water and preventing it from spreading in the aquifer. For this purpose, the equations of the groundwater potential function and the stream function were determined for two pumping wells near a permanent stream. In other words, the real part of the complex potential equation represents the potential function and its imaginary part specifies the stream function; using the image well theory, the effect of the stream was also applied in the problem relations. By determining the coordinates of the stagnation points, the capture zone of the multi-well system was delineated in various configurations and the amount of stream withdrawal was also calculated. The capture zone describes the behavior and capability of the multi-well system by indicating the capture domain of discharge wells for different distances and different pumping rates. Three configurations of the remediation system are presented for two types of critical pumping rates. Under these conditions, it is possible to control the capture zone without intercepting the stream boundary and creating gaps in the extraction region at different distances of the wells with certain pumping rates. At the first critical pumping rate, the capture zone of the double-well system is tangent to the permanent stream boundary, and at a pumping rate below this threshold, groundwater pollution does not reach the surface waters. At the second critical pumping rate, capture zones of two wells merge together. Indeed, in discharges less than this critical rate, there is a distance (gap) between capture zones of the wells and pollution can enter the surface water through this gap. Also, the distance between two wells was determined in the state that both types of critical pumping rate are equal. This case shows a state of capture zone whose boundary is tangent to the stream boundary, and the capture zones of two wells are merged together. In the mentioned state, the dimensionless distance between two pumping wells (the distance between the two wells divided by their distance from the stream boundary) and the dimensionless critical pumping rate are equal to 2×0.58 and 0.33, respectively.