Introduction Climate change is the greatest threat to humanity, because it is the main factor in increasing the frequency and severity of atmospheric events such as droughts, floods, heat waves, etc. that are experienced today. Climate change can cause a wide range of environmental problems, including severe drought and water scarcity, crop loss, and increased socioeconomic consequences. One way to identify climate change is to evaluate climate and temperature indicators. Based on statistical tests and time series of occurrence of these parameters in the long run, the status of change and its trend can be identified. Given the importance of the impact of climate change on all sectors, the study of the consequences of these changes requires the study of all sectors and effective factors with a systemic approach. One of the concerns of human society is the changes that have caused climate change due to global warming. In this regard, given the importance of climate change on all sectors, the study of the consequences of these changes requires the study of all sectors and factors with a systemic approach. Considering the importance of climate change and its effects, this study seeks to answer the following questions by considering important climatic parameters and vulnerable urban dimensions (economic, social, political, environmental): 1-The trend of climate change changes (Temperature and rainfall, humidity, wind speed) what is it like in Ahvaz? 2-What is the causal relationship between the causes of climate change and vulnerable sectors in the city of Ahvaz? 3-What are the effects and consequences of climate change on the city of Ahvaz? Materials & Methods The research methodology is based on statistical tests and qualitative modeling with a systemic approach. The present study analyzes the trend of changes in climatic parameters including temperature, precipitation, relative humidity, and wind speed for a period of 30 years (1991-2020) in Ahvaz using the statistical Mann-Kendall Test was examined. Then, using the science of system dynamics, the causal relationships between variables and structural modeling of the consequences of climate change in Vensim software are investigated. The main stage of using the system dynamics approach is to try to understand and identify the feedback loops of the system under study, for which purpose diagrams of causal loops are drawn. In this study, inputs are the factors that shape climate change are factors that affect the city system. system outputs will be the consequences of climate change. Results & Discussion Based on the results of the analysis of the trend of climatic parameters, the city of Ahvaz in the study period has faced an increase in temperature, increase in relative humidity, decrease in wind speed, and decrease in rainfall. During the 30-year trend (1991-2020), the average rainfall has been (226) mm, each year (1. 32) mm, has decreased and followed a downward trend. The average temperature has been (25. 38) degrees Celsius, it has increased every year (by 0. 051) degrees, which shows an increasing trend over 30 years. Based on the results, the average relative humidity was (41. 1), which increased every year (0. 007). Also, according to the results, the average wind speed is (2. 65 m/s) and has decreased by about (0. 018) every year. Therefore, the wind speed shows a decreasing trend over 30 years. Given that climate change refers to the spatial-temporal changes in the long-term average of climatic elements, the results of this study clearly showed that climatic parameters (temperature, relative humidity, precipitation, wind speed) in the study area have undergone fundamental changes. The consequences of climate change on all economic, social, political, and environmental aspects were evaluated. The results of qualitative modeling and causal relationship showed that climate change in Ahwaz has a direct impact on different sectors of water resources, agricultural production, and energy consumption. Variables of (reduction of water reserves upstream, extreme heat waves) are the most important leverage points of the model. Different outcomes have complex interactions with each other in such a way that they affect different economic, social, environmental, and political dimensions and ultimately intensify each other's effects on reducing the quality of life and increasing climate migration. Conclusion As a result, climate change has consequences such as increasing unemployment, reducing the quality of life, reducing urban resilience, and ultimately increasing climate migration in the city of Ahvaz, and the urban environment is not equipped to adapt to climate change.

This article investigates the problem of simultaneous attitude and vibration control of a flexible spacecraft to perform high precision attitude maneuvers and reduce vibrations caused by the flexible panel excitations in the presence of external disturbances, system uncertainties, and actuator faults. Adaptive integral sliding mode control is used in conjunction with an attitude actuator fault iterative learning observer (based on sliding mode) to develop an active fault tolerant algorithm considering rigid-flexible body dynamic interactions. The discontinuous structure of fault-tolerant control led to discontinuous commands in the control signal, resulting in chattering. This issue was resolved by introducing an adaptive rule for the sliding surface. Furthermore, the utilization of the sign function in the iterative learning observer for estimating actuator faults has not only enhanced its robustness to external disturbances through a straightforward design, but has also led to a decrease in computing workload. The strain rate feedback control algorithm has been employed with the use of piezoelectric sensor/actuator patches to minimize residual vibrations caused by rigid-flexible body dynamic interactions and the effect of attitude actuator faults. Lyapunov's law ensures finite-time overall system stability even with fully coupled rigid-flexible nonlinear dynamics. Numerical simulations demonstrate the performance and advantages of the proposed system compared to other conventional approaches.

A common method for controlling a group of parallel converters in decentralized control strategy structure in an island microgrid, the use is the droop-down characteristics of frequency ω-P and voltage E-Q. However, the problem with using this method is that the reactive power is not properly distributed (in proportion to the capacity of the micronutrients) between the micronutrients, which may lead to overload in the converters. Microgrids may also suffer from dynamic stability problems such as power fluctuations, which can be increased by switching between active and reactive power control. To avoid this problem, the X / R ratio of transmission lines is an important parameter that should be carefully considered in the design of micronutrient controllers. By linearizing and simplifying conditions, the control system conversion function model becomes a single input-single output system, which is efficient enough to show the relationship between control parameters such as slope of droop characteristics and derivative sentences, virtual impedance, and voltage controllers. Using this model, stability conditions for different parameters are analyzed. Also, to improve power distribution stability, common droop strategies are modified by adjusting the slope as well as adding nonlinear sentence sections. This approach reduces the coupling between active and reactive power control and reduces the dependence of power distribution on grid parameters such as the X / R ratio. To evaluate the reliability of the proposed model, the simulation results in a sample island microgrid in MATLAB software are presented.

This paper presents robust optimal control of an uncertain nonlinear switched system with forced subsystems. The uncertainties include external disturbance and parametric uncertainties. Switching signal and control input are designed to minimize a given cost function. Approximate dynamic programming (ADP) has been efficiently applied to certain switched systems as an optimal control strategy. Since approximate dynamic programming method is model based, there would seem to be some difficulties to apply approximate dynamic programming to uncertain switched system. To overcome these mentioned problems, this paper presents an appropriate model. In order to apply proposed control approach, robust time-delay controller is added with ADP control. At first uncertainties are compensated by robust time-delay controller. Then the switching signal and the control input are design by approximate dynamic programming that provides a feedback solution for unspecified initial conditions. The discussing boundedness of states and simulation results verify the effectiveness of the proposed control approach.

Purpose of paper is to use a nonlinear dynamic absorber as beam with concentrated mass at its end to reduce the amplitude of resonant nonlinear oscillator vibration. Primary vibration system consists of mass, nonlinear spring, and viscous damping, and harmonic force is applied to it and causes the system to intensify. nonlinear dynamic absorber has been used to reduce vibration amplitude. First, the kinetic energy and potential energy of system are calculated, and then governing equations of the system are extracted using Lagrange's equations. To solve the governing equations, the method of multiple scales is used. Numerical solution, in the negligible case of considering the mass of the absorber and the stiffness of the nonlinear Duffing spring, the validation of results is done. The effect of nonlinear dynamic vibration absorber on reducing the amplitude of resonant oscillator vibration can be seen well. Influence of the main parameters of the nonlinear dynamic absorber on vibration amplitude of primary system is investigated.

In this paper, the design steps of a multi-model adaptive receding horizon controller for a nonlinear dynamic system are investigated. To implement this control structure, the Takagi-Sugno-Kong (TSK) fuzzy inference system (TSK) has been used to predict the behavior of the dynamic system on a receding horizon. In the proposed controller, the linear part of the TSK fuzzy model is used as a linear model to implement a multi-stage receding horizon controller to calculate the optimal control input sequence. A standard least square algorithm is used to identify the rules consequent parameters of the TSK model. A clustering method is used for partitioning the input-output space in order to generate TSK fuzzy model. Each cluster represents a functional area of the complex dynamic system in the input-output space. In the proposed control strategy, it is assumed that the variables which are used in the premise of the rules are also those which are used in linear models that describe the consequents of the rules. For proper control of the nonlinear system, multiple models are used on the receding horizon. In order to evaluate the proposed control strategy, the proposed control structure has been used to control the power of a nuclear reactor in the charge pursuit problem. The simulation results show the good performance of the proposed control structure.

In this study, the potential of progressive collapse of a four-story steel structure due to the collision of an 8-ton truck with the ground floor columns was investigated. For this purpose, a 4-story steel structure (with intermediate steel moment frame system and special concentric steel bracing in the x-direction and intermediate steel moment frame system in the y-direction) was modeled and designed in ETABS software. ABAQUS finite element software was used to simulate the structure under collision scenarios. In this research, 6 scenarios of truck collision with adjacent columns of the structure have been considered by performing nonlinear dynamic analyzes. The vehicle speed is assumed to be 20 meters per second. The results showed that corner columns are more vulnerable to impact than perimeter columns. The presence of braces reduces the collapse and deformation in the desired scenario. The horizontal displacement in the impacted column in the direction of the moment frame was about 3 times that of in the direction of the dual system. this shows the positive effect of bracing system in reducing the structural responses to impact.

In this paper, the dynamics of multicellular chopper are considered. The model is described by a continuous time three{dimensional autonomous system. Some basic dynamical properties such as Poincar e mapping, power spectrum and chaotic behaviors are studied. Analysis results show that this system has complex dynamics with some interesting characteristics.