Accurate solving of complex systems such as spacecraft is very costly and time consuming. By building a surrogate model, the solution time and the cost can be reduced. The closer the surrogate model is to the actual model, the more accurate the solution and the lower the error rate. Highprecision successor models are called metamodels. The basis of producing a high-precision metamodel is to perform high-precision sensitivity Analysis with a suitable method. sensitivity Analysis can show the effect of input variables on output variables and produce a surrogate model by eliminating ineffective input variables. Therefore, sensitivity Analysis is highly valuable in solving complex systems. The purpose of this article is to analyze the sensitivity of the Multidisciplinary design of a monopropellant liquid propulsion system by the Latin Hypercube Sampling method. In this article, the topics related to the liquid monopropellant propulsion system are divided into six parts: High pressure gas tank, liquid fuel tank, injector, decomposition chamber, catalytic bed and nozzle. By determining the input and output variables of each subject, the results of sensitivity Analysis are displayed in two ways: the sensitivity of the input variables to the output and the two-by-two correlation of the parameters with each other. In the results, as can be seen, the specific impulse input variable, in the high-pressure gas tank and the liquid fuel tank, has no effect on the output variables. In the injector, the number of grooves, groove angles and fuel tank pressure do not have a significant effect on the output variables. In the decomposition chamber sensitivity Analysis diagram, the radius of the granule and for the catalyst bed, in addition to the radius of the granule, the percentage of ammonia decomposition are also ineffective. Finally, the sensitivity Analysis for the nozzle shows that the ratio of specific heat has no effect on the output variables.

Facilities built in areas affected by earthquake activity, such as tunnels, which have always been an integral part of human life, must withstand both dynamic and static loading. It has led to the need for practical studies on the effects of earthquakes on underground structures and the factors affecting their destruction. For this purpose, in this research, at first different patterns of tunnel’s excavation were investigated and by using Plaxis 2D software and based on Tabas earthquake in Iran, sensitivity Analysis on geotechnical parameters of the soil surrounding tunnel such as cohesion, friction angle, unit weight and modulus of elasticity was carried out, and the parameters whose changes have the greatest and least effects on the bending moment changes on the tunnel lining are introduced. The results show that tunnel excavation patterns significantly affect the bending moment, axial forces, displacements, and surface settlement of the tunnel. Often, by dividing tunnel excavation area to small parts, the values of bending moment, axial forces, displacements, and surface settlement of the tunnel decreases in static Analysis. Also, outputs of sensitivity Analysis on geotechnical parameters of the soil surrounding tunnel showed that modulus of elasticity of the soil surrounding tunnel has the most effect and cohesion changes have the least effect on bending moment induced on tunnel lining..

In recent years, the use of air taxis as a suitable solution for transporting cargo and passengers, has been considered especially in short distances and in the city. Complex systems, such as air taxis, are involved in several subsystems with interacting and sometimes conflicting effects are difficult to be derived. Modern optimal design methods such as Multidisciplinary design optimization can derive the optimal design while satisfying all the constraints and limitation. In this article, Multidisciplinary design optimization of an air taxi is discussed. The optimization framework is selected based on AAO by considering structure, aerodynamics, flight mechanics, propulsion and electrical power. Total mass of air taxi is selected as cost function. Finally, the optimal results are compared and evaluated with the results of two classical design methods including "weight estimation" and " sensitivity of design coefficients". The results confirm the improvement of optimal solution with compare of classical methods.

This paper presents an efficient global meta-model building technique for solving high fidelity Multidisciplinary design optimization (MDO) problems. The main difficulties associated with MDO are often characterized by interdisciplinary couplings, high computational cost of an Analysis in individual disciplines and a large number of design variables and constraints. These issues result in very high overall computational cost limiting applications of MDO to complex industrial design problems. To address these issues a combination of global meta-model using moving least squares (MLSM) and the trust region strategy is introduced. A global meta-model is used to identify the feasible and infeasible regions and the trust region strategy is used for a detailed search of the feasible region. The technique is demonstrated on a test problem and the effectiveness of the method for modeling and system level collaborative optimization using high fidelity models is studied. The results show that meta-model based on MLSM provide a high degree of accuracy whilst achieving a considerable reduction in computational cost.

There is no determined method for Micro Air Vehicles (MAVs) design (unlike full-scale aircraft), so MAVs design is very complex and vague. For this reason, the design of MAVs is very expensive (time-consuming), and finally, the obtained design could not be more optimal. To solve these challenges, this study developed a framework for Multidisciplinary design Optimization (MDO) of fixed-wing MAVs. This framework aims to use the benefits of MDO (time reduction and achieving optimal design) in the design process of MAVs. So, it is tried to consider the most important modules for Analysis, and the framework can consider all flight phases in the design optimization process. Geometry, weight, the center of gravity, aerodynamics, and power are the considered modules in this framework. The Analysis of all modules is performed for the entire flight phase. To show the performance of this framework, the design optimization of a fixed-wing MAV has been done by considering take-off weight and drag as objective functions.  The considered constraints for this research are from stability and geometry modules. It is worth noting that with attention to the complex design space of MAVs and the capability of the Genetic Algorithm (GA), this algorithm has been considered as an optimization algorithm in this study.

Optimal Manned Space Launch System Conceptual design with Modular design and sensitivity Analysis Approach The purpose of this article is to optimal manned space launch system conceptual design methodology with combination of modular design (by using clustering the existing motors to provide the thrust force) and sensitivity Analysis (by varying the affected parameters to achieve the capability) approach. This methodology is implemented according to the human departure to space program and higher strategy document (country’ s aerospace development comprehensive document). To this end, in the methodology is utilized both of the statistical and parametric (the space launch system optimized main parameters) methodologies, is determined the optimum thrust level based on the three fundamental requirements (number of stages, number of engines in clustering and maximum axial acceleration). These fundamental requirements are affected on risk and manned space launch system axial acceleration. In the paper, the purpose of sensitivity Analysis is to determine of value of effective of main design parameters on space launch system capabilities. The method for optimizing and design space searching is utilized from Genetic Algorithm (GA). Finally, the suggested methodology and mass – energy capabilities will be verified by comparing the results of two methodology (statistical and optimal) to achieve the specific mission.

A new approach to the design and development of launchers is the use of advanced technologies to reduce design and development costs as much as possible. In this paper, an approach to reduce costs and increase reliability is proposed, which is based on the use of a non-turbo pump propulsion system (pressure-fed propulsion system) instead of a turbo pump propulsion system. For this purpose, the Multidisciplinary conceptual design optimization of a two-stage launch vehicle with a pressure-fed propulsion system with the aim of sending max payload with a least gross mass to the orbit (500 km) in terms of structure, aerodynamics, propulsion, pressure vessels, simulation, and pitch program disciplines. Then, the sensitivity Analysis was performed on the optimum launcher to determine the efficiency of the launcher at different orbital heights and the ability to carry a suitable payload.

The need to improve the reliability and safety requirements, has led to increasingly utilization of reliability based design approaches. In this study, reliability based Multidisciplinary design optimization for a bipropellant propulsion system has been investigated. The objective function is minimizing the total system mass and design constraints are the total impulse and the temperature of the wall of the combustion chamber. Monte Carlo simulation methodology is used to apply uncertainties in the problem and to show the reliability of the system under these uncertainties. The mass, functional and geometric results of the bipropellant propulsion system are differentiated for optimal design, reliability based design and optimal reliability based design. Then, considering the results, the concepts and definitions of design methods are compared and discussed and it is shown that the reliability based Multidisciplinary optimization while having the desired mass, has high reliability.

This paper deals with the sensitivity Analysis and optimization of system parameters for a classical slider-crank mechanism as a multibody system which includes a clearance between the joints of coupler and slider. Due to the nonlinearity involved in the dynamics of clearance joints, the base reaction force, exerted on the base from the crank, changes roughly and does not vary as smooth as the case of the mechanism with ideal joint. Variation of the base reaction force can be a measure of the undesired vibrations induced due to the effect of clearance joint. After deriving the equations of motion and modeling the clearance, the direct differentiation method is used to conduct a local sensitivity Analysis to assess the sensitivity measure of the base reaction force on some kinematic and contact parameters. The results show that the reaction force is more sensitive to the variation of link lengths and link masses compared to the variation of contact surface characteristics such as Young’ s modulus, restitution coefficient and contact generalized stiffness in most parts of the motion cycle. On the other hand, the sensitivity of the base reaction force to the clearance size is very higher than its sensitivity to the above-mentioned kinematic and contact properties. Finally, based on the results of the sensitivity Analysis, an optimization procedure is used to reduce the amount of the maximum base reaction force by choosing the optimized link lengths.