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The main goal of this study is the classification of international risks facing Iranian automotive companies activated in international markets. Also, the examination of the relationship among these risks and the selection of entry mode to various countries by these companies is another goal of this research. The research population of this study is the factories in automotive industry which has entered foreign markets in recent 5 years (1385-1390). Analysis even data surface is elected "Company-Project" and exploratory factor analysis test is used for the classification of risks. In this manner, international risks are classified in the four categories of risks; specific-host country risk, specific-industry risk, specific-company risk, and specific-home country risk. Also, the relationship between international risks and the selection of entry mode is examined by Spearman correlation test and its results are the confirmation of relation specific-host country risk and specific-industry risk with the selection of the entry mode. In other words, according to findings, with increase in the mentioned risks, the export entry mode has been considered and with decreasing of the risks, the entry mode has inclined to the J.V. and foreign direct investment. On the other hand, it has been identified that the relationship between the entry mode, specific-industry risk, and specific-home country risk is not meaningful.  

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During the Industrial Revolution and particularly at the beginning of the Second World War, mathematicians and those involved in the industry became interested in the optimization models. The application of these model was specially developed in industry and services sector after the Second World War. Based on this, designing of the mathematical model for the transportation network of Islamic Republic of Iran’s Post Corporation, which is practically complicated as a result of the multiplicity of communication paths and the variation of transportation systems and vehicles as well as mail items, will be studied according to a multi-level model. First the transportation system’s data is loaded into the post corporation’s system of transportation data. After estimating the Function Utility of the system, the shortest time and path as well as the vehicle carrying the intended mail item between the two post offices (i & j) will be identified. Finally, the consignments will be transported through the selected paths and based on their weights. Therefore, besides reviewing the related literature, the history of transportation systems as well as postal transportation systems will be discussed. Finally, based on the methodology, the findings and proposals will be presented through a multi-level mathematical model.

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Vehicles are subject to random road excitations due to road unevenness and variable velocity which causes ride discomfort and fatigue. Ride comfort could be improved by decreasing vehicle accelerations. In this paper, to evaluate the vehicle ride comfort, root mean square acceleration response (RMSAR) is calculated using power spectral density (PSD) of road excitations and these quantities are compared with the ISO2631 boundary values. Then by considering ISO2631, the vehicle’s RMSAR is minimized by optimal design of vehicle suspension viscous damping and stiffness parameters. To solve this nonlinear constrained optimization problem, we utilize genetic algorithms. Also, in the design process the physical restrictions are included. Obtained results demonstrate a considerable improvement of vehicle ride comfort and its dynamic response as a result of reduced accelerations. Comparing the obtained results with those obtained by method of nonlinear programming confirms the supremacy of genetic algorithms.

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In this paper the idea of energy regeneration of active suspension system in hybrid electric vehicle is presented and its influence on the fuel consumption and emissions of vehicle is investigated through computer simulations. Active suspension systems employ active actuators to apply force and control the vibrations of vehicle body. The active actuators either insert energy to the system or extract the energy of vibrations when required. Using an energy regeneration system, the extracted energy of vibrations can be recovered and stored in the energy storage system. In hybrid electric vehicles, the active suspension supplies its required energy from the electric energy storage system of vehicle. In this work, a hybrid battery/supercapasitor energy storage system is employed to supply the required energy of active suspension and other electric components of vehicle. The simulation results show that with application of the energy regeneration system, the fuel consumption and exhaust emissions of vehicle is reduced.

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The share of DC-based Renewable Energy Resources (RERs) and electricity storage systems are increasing due to developments of smart grid technologies. Moreover, the share of DC-based load has rapid growth due to significant developments of power electronic technologies. Therefore, a more flexible power system is required for efficient integration of emerging loads and generators. In this paper, hybrid AC-DC Local Network (LN) is incorporated as an appropriate topology versus conventional AC LN to reinforce the integration of RERs and Plug-in Hybrid Electric Vehicles (PHEVs). A mixed integer linear model is developed for operation of both hybrid AC-DC LN and conventional AC LN topologies considering high penetration of RERs and PHEVs. This operation model is solved by GAMS optimization software to minimize the operation cost and find the optimum inter-resource scheduling in the day-ahead market. Moreover, investment analysis and reliability assessment are carried out for the mentioned LNs. Numerical study is conducted to evaluate the ability of both topologies for better utilizing the opportunities of integration

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To prevent unpleasant incidents, preservation high-speed railway vehicle stability has vital importance. For this purpose, the Railway vehicle dynamic is modeled using a 38-DOF includes the longitudinal, lateral and vertical displacements, roll, pitch and yaw angles. A heuristic nonlinear creep model and the elastic rail are used for simulation of the wheel and rail contact. To solve coupled and nonlinear differential equations, Matlab software and Runge Kutta methods are used. In order to study stability, bifurcation analyses are performed. In bifurcation analysis, speed is considered as the bifurcation parameter. These analyses are carried out for different wheel conicity and radius of the curved track. It is revealed that critical hunting speed decreases by increasing the wheel conicity or decreasing the radius of the curved track. Keywords: railway vehicle dynamics, nonlinear creep model, critical hunting speed, numerical simulation, bifurcation analysis Keywords: railway vehicle dynamics, nonlinear creep model, critical hunting speed, numerical simulation, bifurcation analysis

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Design of a suitable Control Strategy for operating a hybrid propulsion system in different types of roads and driving cycles is one of the most challenging subjects in hybrid vehicle research areas. Intelligent Control Strategies have been designed to meet the above requirement. The control signals in an intelligent control strategy of the hybrid vehicles are generated according to the driving cycle type. This is done by using a driving cycle identification unit. In this paper, design of a fuzzy based driving cycle identifier has been presented. The main idea in this unit is that any arbitrary driving cycle is similar to a group of standard driving cycles according to some degrees of similarity. As a result, the control strategy of the hybrid powertrain in the arbitrary driving cycle is affected by the optimized control strategy of the standard diving cycle based on the degree of similarity. Here, the subset of sufficient features is determined by using the floating search method as a useful feature selection algorithm. Also, the fuzzy clustering method is used to generate the values of similarity degrees to each standard driving cycle. Finally, the performance of the fuzzy driving cycle identification unit is assessed.

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In this paper, we investigate a decision support system (DSS) for the resolution of real-life vehicle routing and scheduling problem (VRSP). Scheduling the deliveries from a regional distribution centre (RDC) to large stores of a major fmcg retailer includes every possible vehicle routing complexity. Usual constraints that are seen are: size of the vehicle and the length of the driving day, loading feasibility of products in different parts of the vehicle, and also with various time windows. More importantly, in this scheduling decision-making is customer oriented, in which, Customer's value for the company is considered as one of the most important factors. The algorithms for the resolution of the distribution problems constitute a very important part of DSS. Therefore, a simulated annealing based algorithm has been developed to speed up the process by circumventing the need for the skeletal schedule.

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In this paper, a real time simulator of the engine-generator for a series hybrid electric bus is designed which can be used for hardware in the loop testing of the hybrid bus control unit. As an important step for designing a hardware in the loop simulator, messages that the engine and generator receive from the vehicle control unit are identified. Design of the simulator is based on these received messages and dynamic behavior of the components. Since the engine and generator receive speed or torque commands from the vehicle control unit, two PID controllers are designed to bring the engine or generator to the desired speed. By applying appropriate inputs, different modes of operation of the diesel-generator is simulated including the soft start process and steady state operation. For a simulator, the ability to interface with a real hardware requires a real time simulation. To do so, the design process is implemented in LabVIEW environment and results show that the designed simulator gives responses close to real test results and it is suitable for developing the hybrid vehicle control unit.

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The accurate, correct, and quick calculation of vehicle longitudinal velocity during braking plays a vital role in the precise operation of Anti-lock Brake System (ABS). Therefore, different researches have been conducted in the field of vehicle longitudinal velocity estimation. But, most these researches have been faced with a problem so called using braking torque as a known input to an estimator. These researches have addressed the issue while measuring the braking torque is not easy and needs expensive and additional sensors which causes the increase of costs and also requires more attention to maintenance and repair problems. In this paper, two approaches, Unknown Input Iterated Extended Kalman Filter (UIIEKF) and Modified Nonlinear Adaptive Filter (MANF) are proposed in order to estimate vehicle longitudinal velocity so that they do not need a braking torque and both methods have acceptable accuracy. The main difference between these two approaches is that the UIIEKF requires the dynamic model of vehicle motion during the braking process to estimate the longitudinal velocity while the MANF is model-free. Different aspects of both methods are analyzed by experimental tests on the vehicle and finally advantages and disadvantages of the both methods are compared.

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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 on-board 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.

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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.

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Modeling of a Sport Utility Vehicle as it moves on two wheels studied in this paper. Our major purpose concentrated on developing a general criterion to specify rollover threshold. First, model of vehicle as it sustained on two wheels derived that its results used to develop rollover threshold of Sport Utility Vehicles. In addition, these results could be valuable to design new controllers, which are able to prevent rollover at the best state of vehicle dynamics. After vehicle modeling, appropriate model for tire forces and moments picked up from the most related and available references. Then validation accomplished as final part of modeling section. Stability of presented model studied as an important part of this paper. In order to specify rollover threshold as vehicle moves on two wheels, steady-state equations of motion used and based on steady state analyses a new criterion proposed. Next, by designing some maneuvers, simulations accomplished to show applicability of proposed criterion at different situations. As conclusion, presented criterion is more implementable and efficient than other proposed model for rollover threshold and can prospect rollover threshold at various steering angles and longitudinal speeds as model inputs.

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Due to the complexity in the control system of hybrid vehicles, the electronic control units should go through extensive testing before getting installed in a prototype vehicle. In the first stages of the development process, Hardware-in-the-Loop (HiL) simulation can not be performed because the hardware components of the vehicle are not yet available. In this case, Model-in-the-loop (MiL) simulation is used which couples the designed control software with an environment simulation with no need for a special hardware. In this paper, the MiL simulation is introduced for verification of the vehicle control software in a series hybrid electric bus. To do so, considering the dynamic behavior of various components of the vehicle, a simulator of the hybrid bus is designed by going through with the input/outputs of the vehicle control software. Using the designed test bench, the user can act as a real driver and experience different driving regimes and analyze the control software commands. In the designed simulator, all subsystems are simulated separately in LabVIEW environment and real-time simulation is achieved with an acceptable error. Therefore, it can be used in a HiL test bench for testing each of the vehicle components. The designed simulation model has been validated using real test results. Using that, results show that all control functions in the vehicle control software can be tested and verified with no cost and in the shortest possible time.

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In this paper, the problem of the navigation error effect for the optimal and constraint Trajectory of the UAVs that are required to fly at low altitude over terrains has been discussed. Due to the increasing deviation problem of inertial navigation systems in terms of time, having a safe flight and collision avoidance with terrain at low altitude is the main point in the trajectory design of this type of the vehicles. On the other hand, some of these vehicles use Terrain Contour Matching (TERCOM) as a navigation aiding system. This system is more efficient in rough terrains, and providing the requirements of this system beside other constraints is a complex task. In this paper is tried to meet these constraints in the trajectory design process. For this purpose, an algorithm based on the layered network flow on the digital terrain maps used in a manner that has a high potential in adoption of various constraints and optimal trajectory is generated. Then, using equations of motion on a terrain digital data in 3D space with the dynamical constraints and different optimality criteria, a complete model of navigation error and also parameters affecting TERCOM has been developed to generate feasible path reducing terrain collision probability to zero.. Numerical results show validity of this issue.

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In this study a safe and smooth path planning containing the slightest risk is considered for an Unmanned Underwater Vehicle (UUV). To do so, three smooth and continues functions resembling the three dimensional path are introduced and then their parameters are optimized using the particle swarm optimization method to find the safest possible path. For each point in space a numeric value is considered as vulnerability and the objective function is the integral of the vulnerability over the path produced. This path forms controlling signals which through a TSK fuzzy controller, the UUV is guided. The new arrangement of the propulsion vehicle subsurface was modeled. Since for the design of the controller, the parameters of the Under Water Vehicle dynamic system not used, so the control system is robust with respect to parameter Uncertainties. In the last section three environments with different complexities are considered to illustrate the creating process’s performance of the path and it is concluded that this method demonstrates desired performance in the development of a safe and smooth path through a harmful environment and the design of an adequate controller.

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Nowadays, a great number of researches are done by scientists to provide some models that can predict the passenger injuries in crashes. In this paper, a hybrid model of vehicle and passenger is proposed to predict the head acceleration in the front crash. A lumped mass model with 12-degree-of-freedom (DOF) is firstly used to predict the behavior of vehicle in front crash. In this model, any member of vehicle is modeled as a lumped mass and connected to the other members through some springs and dampers. The unknown coefficients of such model are obtained using genetic algorithm to minimize the deviation between the results of experimental and suggested model. The parameters of model are established by experimental results of a real world car, namely the HONDA ACORD2011, in an accident velocity of 48 km/h. Also, the validity of the proposed model is checked by experimental results of mentioned vehicle at two other crash velocities of 40 km/h, and 56 km/h. The results show that the proposed model is an efficient framework for preliminary designing of both structure and parameter design of vehicle to improve its crash worthiness. Moreover, a multi-body dynamic model of driver is proposed to predict the head injury in front crash. The seat acceleration which has been calculated using vehicle’s model is considered as input of this model.

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In this paper the effect of horizontal control surfaces (stern fins) angle on the drag force of the Subsea R&D Autonomous Underwater Vehicle (AUV) is investigated using both experimental fluids dynamic and numerical fluids dynamic methods. The experiments were conducted in the Subsea R&D towing tank using a 1:1 scale model of the AUV, at various stern angles and in a speed range of 1 to 3 m/s. A pair of Naca shaped struts was used to connect the AUV to the carriage dynamometer. The stern drag force was experimentally calculated at various stern angles and towing speeds. The results obtained by experimental method compared with those obtained numerically by commercial computational fluid dynamics CFX code. Both experimental and numerical results showed that as the stern angle increases, the total AUV drag force increases, and the drag force coefficient can be estimated by a second order polynomial. The results showed that, at a speed of 1.5m/s, as the stern angle increases to 45 degree, the drag coefficient increases up to 174 percent It was also observed that at a specific stern angle, the drag force due to stern fin increases with the AUV speed. Variation of axial force as a function of stern angle was determined by using both experimental and numerical methods. The results obtained by both methods showed that the expensive experiments conducted in towing tanks can be replaced by numerical simulations.

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In this paper, the effect of passengers on the chaotic vibrations of the full vehicle model is investigated. The vehicle system is modeled as a full nonlinear seven-degrees of freedom with an aditional one -degree of freedom for each passenger. Four passengers are added sequentially to the vehicle that produces eight, nine, ten and eleven degrees of freedom models, respectively. The effect of passengers on the chaotic vibrations of vehicle is studied for the above mentioned cases. The nonlinearities of the system is due to the nonlinear springs and dampers that are used in the suspension and tires. Roughness of the road surface is considered as sinusoidal waveforms with time delay for tires. The governing differential equations are extracted by Newton-Euler laws and are solved numerically via forth-order Runge-Kutta method. The analysis is conducted first by detecting the unstable regions of the system and then followed by a specific excitation frequency, where there is possibility of chaos. The dynamic behavior of the system is investigated by special nonlinear techniques such as bifurcation diagram, power spectrum, pioncare section and maximum lyapunov exponents. The obtained results represents different types of nonlinear dynamic absorbers in the vehicle with and without passengers. Consideration the passengers and increasing the mass of the system can resultes in a significant changes in the dynamic behavior where improves the chaotic vibration of the vehicle.

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In articulated vehicle, the importance of adjustment or confinement of the side slip angle has not yet been investigated. However, their proper dynamic behavior is of great significance. In this research, based on a planar model of articulated vehicle and adopting a proper method, the significance of this quantity is examined. In this article, after a review of the literature, the articulated vehicle model is clarified. The selected model is a validated model of articulated vehicle with 14 degrees of freedom that simulates the vehicle’s directional dynamics. In the analysis of the stability, phase plane method based on the nonlinear model of articulated vehicle with three degrees of freedom is used, which includes the major degrees of freedom in planar motion. In this section, the traction phase plane is drawn via two variables, the side slip angle and the rotational velocity of the articulated vehicle by terms of constant longitudinal velocity of the vehicle as the critical condition and then stable and unstable zones are separated. Fuzzy estimator systems have been based on the Takagi-Sugeno fuzzy model and offer a stable range for the articulated vehicle’s motion according to the results from the phase plane. Finally, the application of phase plane in studying the stability would be magnified by designing two control systems based on the stable range, in order to control the articulation angle and the side slip angle. Eventually, the results are analyzed, and the method is tested based on the vehicle’s full model.