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Abstract This paper focuses on layout modeling and optimization for a space control system. Majority of recent research works consider design components as constant elements over time. A new approach based on variable mass components is proposed in this paper for which the objective function is to minimize mass center variation (MCV) range over time. The proposed approach consists of Human-computer interaction (HCI) and Optimization methods to perform the layout. In the modeling phase, using defined inputs, all system components are determined. In the next step, mathematical model of achieved layout is defined. Mathematical model includes objective function, constraints, variables and parameters, play an important role in choosing appropriate optimization method. Based on mathematical model and design space, a gradient optimization method is selected. By applying this algorithm, optimum layout is proposed. Results of optimization and HCI design are compared. Comparison of the results shows that the optimization technique can significantly improve the results of the layout problem. At last, the results have analyzed and validated with similar research works. The results comparison show more efficiency and accuracy for the proposed method.

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Free hydroelastic coupled vibration analysis of frictionless liquids with a free surface in spherical tanks with a flexible bottom has been performed. The side wall has been considered to treate as a rigid body. The flexible bottom treats as a membrane at a certain distance bellow the center point, and the free surface is considered as a cross cutting at the top of the center point. The spherical coordinate system is adopted to derive the governing coupled equations, and finally a vibration analysis is carried out, using the traditional Galerkin's method, leading to closed-form solutions. Effects of various system parameters, i.e., membrane tension, liquid density, geometric parameters of the system such as the container radius, free surface distance discriminate parameter, and bottom distance discriminate parameter on the vibration behavior are investigated. The novelty of the present work is to obtain direct formulas for hydroelastic coupled vibration analysis of the mentioned system, which can be easily used in engineering design applications. Coupling between two mode numbers can be clearly seen in results, in other words, there is a coupling between vibration modes as interaction in spherical geometry.

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In the present paper, a hybrid filter is introduced to simultaneously preserve the stability and accuracy and also to eliminate unwanted oscillations in the numerical simulation of shock-containing flows. The fourth-order compact finite difference scheme is used for the spatial discretization and the third-order Runge-Kutta scheme is used for the time integration. After each time-step, the hybrid filter is applied on the results. The filter is composed of a linear sixth-order filter and the dissipative part of the fifth-order weighted essentially non-oscillatory scheme. Using a shock-detecting sensor, the hybrid filter reduces to the linear sixth-order filter in smooth regions and to the fifth-order weighted essentially non-oscillatory filter in shock regions in order to eliminate unwanted oscillations produced by the non-dissipative spatial discretization method. The filter performance and accuracy of the results are examined through several test cases including the linear wave equation and one- and two-dimensional Euler equations of gas dynamics. The results are compared by that of a hybrid filter which is composed of the linear sixth-order and the second-order linear filter and that of the fifth-order weighted essentially non-oscillatory scheme.

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In present work, heat transfer and flow pattern map of dimpled and horizontal tubes were studied during phases of boiling and condensation of mandatory convection of hydrocarbon R600-a. Empirical relationship will be expressed based on empirical data obtained by such experiments and fit the experimental results and Matlab software to show flow pattern map for such refrigerant with proper accuracy. The cycle consists of a pump, two preheaters, two testing parts, two condensers, flow meter and reversing valve. In this study, experimental evaporator is a copper tube with internal diameter of 8.7 mm and length of 1200 mm. the heat required for fluid evaporation is supplied by thermal element twisted around it. Such tube has been designed in forms of dimpled and straight models to evaluate effect of placement of dimples inside tubes. The test was conducted by refrigerant mass flow between 155 and 470 kg/m^2 s and vapor quality between 0.05 and 0.78. Moreover, flow patterns and their transitions for refrigerant R-600a during flow boiling inside a helically dimpled tube and a smooth tube were visually observed and analyzed. Annular, intermittent, and stratified-wavy flow were recognized for plain tube whereas there was no stratified-wavy flow in flow pattern visualization of dimpled tube. Investigation clearly shows that the dimples in evaporation significantly impact the two phase flow pattern. Inside the helically dimpled tube the intermittent/annular transitions occurs at lower vapor quality value than for the smooth tube.

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One of the methods for solving Navier-Stokes equations in order to analyse aerodynamic flows is using finite volume method. Since aerodynamic flows are mostly in the range of compressible flows, here one of the density based algorithm (CUSP) have been studied to connecting equations. So here by adding LD (Low diffusion) part to the CUSP method a new method LDE (Low diffusion E-CUSP) have been created which containing new improved discretizations and it has been extended for a unstructured two dimensional mesh. Because of using edge-based data structure it gives the ability to solve the unstructured and structured meshes. Also the discretization of time section is done explicitly by Runge-Kutta method. It has acceptable stability range in compare with the amount of calculation utilized. Then, the results of new improved method (LDE) have been studied for a unstructured 2d mesh and compared with old method which it has been improved for unstructured mesh. The results show that the convergence time and the number of iterations to reach desired error are reduced. Also error percentage of numerical results like pressure coefficient is reduced. Moreover, dissipation of this new method does better than first method in terms of capturing shock location in a proper way.

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In the present study, evaporation heat transfer and frictional pressure drops of refrigerant R-600a (iso-butane) inside a helically dimpled tube and a plain tube of internal diameter 8.3mm were measured and analyzed. All tests were performed at different vapor qualities up to 0.8 and average saturation temperatures ranging between 38 and 42℃. Refrigerant mass fluxes varied in the range of 114-368 kg/m2s. The inner surface of the helically dimpled tube has been designed and reshaped through three-dimensional material surface modifications consists of both shallow and deep protrusions which is placed evenly in helical directions on the tube wall. The experimental results show that the heat transfer coefficients of the dimpled tube are 1.29-2 times larger than a smooth tube with a pressure drop penalty just ranging between 7% and 103% larger than the smooth tube. Moreover, Performance Evaluation Criteria (PEC) dubbed Penalty Factor (PF) and Total Temperature Penalization (TTP) boiling inside a helically dimpled tube and a smooth tube were analyzed which are a convenient way to relate the two penalization components and provides a rational method to compare the exergy losses associated with frictional pressure drop and heat transfer coefficient.

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One of the main problems in the commercial use of lithium-ion batteries for high energy consumption is the heat problems associated with these batteries. Since many batteries are used together in order to generate higher power, it is important to predict their thermal performance. In this study, a heat management system of a lithium-ion battery equipped with a heat pipe is investigated. For this purpose, a part of a battery pack consisting of two batteries and a heat pipe is selected and its performance is experimentally investigated. These tests are performed at various ambient temperatures through a made test chamber with the ability to accurately control temperature. The experimental results show that although with increasing ambient temperature, the battery surface temperature increases, but due to the decrease in thermal resistance of the heat pipe, the effect of this temperature rise can be moderated and work as an active method. In addition, using forced convection in the condenser section, not only can the battery surface temperature be controlled below 40 ˚C, but it also distributes the temperature uniformly over the battery surface. The use of the heat pipe also helps to maintain more stable temperature conditions with lower temperature fluctuations in consecutive battery cycles.

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Environmental security is one of the most important aspects of human security, which puts emphasis on sustainability of the developmental policies and that they should adjust with the environment as well as rights of future generations. Since threats to the human security mainly occur within environmental issues, this research- highlighting the relationship between human security and environmental security and pointing out the threatening causes and factors to the human security - has replied to the question that how has the environmental degradation endangered human security in Iran? This study shows adoption of policies like 1- Expansion of urbanization, 2- Population growth, 3- Consumerism and stressing the production increase, disregarding its consequences, and 4- Development of environmentally incompatible technologies have led to further utilization of fossil fuels as well as uncontrollable use of various environmental resources, increased pollution, and extensively damaged the environment which consequently endangered human security due to the severe dependence of human being to the environment.

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cost-effectiveness, and reliability. Despite numerous experimental studies on pressure-swirl atomizer spray, a comprehensive mathematical model for predicting spray characteristics has not yet been presented. Additionally, there is no consensus on the distribution function accurately describing droplet size dispersion. In the present study, the main characteristics of pressure-swirl atomizer spray, including discharge coefficient, spray cone angle and droplet size distribution, were experimentally investigated using the shadowgraph technique. The study spanned a wide range of Reynolds numbers, from 1250 to 8500, encompassing laminar, transition, and atomization regimes. The findings showed that the discharge coefficient initially declined during the transition stage, followed by a gradual increase up to the atomization regime. In the atomization regime, the discharge coefficient remained almost constant. A similar trend was observed for the spray cone angle throughout the transient and atomization phases. The gamma distribution function provided a favourable fit with the experimental drop size distribution in the near-ligament location, where primary breakup mechanisms dominate. The log-normal distribution function showed superior fitting with the experimental droplet size distribution for regions distant from the liquid sheet disintegration point, where secondary breakup mechanisms exert a more pronounced influence on droplet dispersion. Overall, these findings provide valuable insights into spray characteristics and associated uncertainties.

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According to experts, reforms in Saudi Arabia since 1991 have been significant and ongoing due to their specific course and direction, as well as the presence of supporting forces that make it necessary to refer it as a “trend”. The Future Reforms in the kingdom under Vision 2030 will also be directly affected by such forces. As such, the main questions in this article are: What are the important and influential propellants of Saudi Vision 2030? What is the ranking of these propellants and their relationship with reforms? To respond to these questions, 16 drivers were extracted and their importance and uncertainty were determined in the Delphi stage. Subsequently, with the help of Wilson Matrix, key and important drivers of the scenario were identified and by interviewing 17 experts, the relevance of each of these drivers for the future of reform in the country was determined. The findings show that the drivers such as "western demands and pressures ", "efforts to legitimize governance”, “Saudi regional competitions" and "conflict of political elites" are important for future Saudi reforms. The research method applied in this study is descriptive-explanatory and analytical and data gathering is based on library and combined interviews with experts.