Sharif Digital Repository

In this article, an optimal maneuver structure is proposed to improve the cruise fuel consumption performance of a transport category aircraft. The maneuver is taken by analogy to the natural phenomena of fish movement in the water. By using fish-like locomotion and implementing it on a transport category aircraft, better performance economy has been realized in cruise flight. The maneuver structure and the required control actions are extracted using optimal control theory. The power required during a specified cruise time span is taken as the merit function in the optimal control formulation. The cost savings associated with this type of optimized periodic maneuver during cruise is... 

Riding comfort, driving stability and drivability are important factors in good vehicle performance. These factors are heavily subject to low frequency vibration generated by engine. A recent tendency in engine mounting system design is the insertion of a sub-frame. In this paper a complete model of a typical vehicle is simulated with and without sub-frame. An acceleration analysis is studied for three important parts; steering roll, pedals and beneath of the deriver's feet. Also the effect and importance of existence of engine mount is studied by removing one engine mount. The results are presented graphically and show how using sub-frame improve the isolation of body vibration due to the... 

Fault monitoring in internal-combustion engines is crucial for keeping the vehicle performance within the acceptable standards of emission levels and drivers' demands. This paper analyses how a vehicle's performance and engine variables are affected by a leakage fault in the exhaust manifold. The threshold leakage that causes the vehicle to exceed the emission standards is determined for a class M1 vehicle tested on a chassis dynamometer over the New European Driving Cycle. It is shown that, when a leakage of 6 mm diameter on the exhaust manifold is introduced, the vehicle emissions exceed those specified in the European 2013 on-board diagnostics standard. In addition, the effects of the... 

Matching diagram is a key part of the conceptual design process to determine the wing area and the required power. However, it requires drag polar estimation and the assumption of maximum lift coefficient. In case of conventional manned aircraft, early estimation techniques are based on statistical data that are not suitable for hand-launched aircraft. In this study, it has been attempted to present the performance calculations and a proper conceptual design model by acquiring sound values for the aerodynamic coefficients in low Reynolds number, using statistical wetted area as well as a raw design of fuselage, wing and tails. The process is applied to a sample scenario and the results are... 

The level and character of noise emitted by exhaust system has significant effect on the overall acoustic performance of vehicle powertrain and sound quality which is received by occupants. In addition to meeting aforementioned objective, the exhaust system must meet exterior noise regulation which is ordered by governments. In this study, acoustic performance of the vehicle exhaust system is investigated. Numerical simulation is applied for this aim that is the fastest and the most economical method in early design stages of vehicle development process. Thickness optimum design is performed in order to improve acoustic performance of exhaust system. Robust parameter design, based on Taguchi... 

The present paper discusses the possibility of adding recycled polymer fibres to high performance concrete (HPC). Fibres used in this study were recovered from discarded car timing belts. To investigate different characteristics of the concrete specimens several destructive and non-destructive tests, such as compressive strength, modulus of rupture, flexural toughness, ultrasonic velocity and electrical resistance tests were carried out. In addition, slump flow tests were conducted on the fresh concrete. Experimental results from the study showed that the use of low percentages (up to 0.5%) of waste fibres improved the modulus of rupture and flexural toughness. Based on ultrasonic and... 

This paper investigates three different strategies for centralized charging/discharging management of electric vehicles, their features and the impacts on technical performance of distribution systems. Three goals of load factor maximization, load variance reduction and energy loss minimization are chosen as the main technical factors need to be optimized in the proposed electric vehicles charging/discharging management strategies. In this regard, at first, the mathematical model of these strategies for both cases of with/without vehicle-to-grid (V2G) programs are extracted. Then, solving procedure of the attained optimization problems with different optimization methods are explained. These... 

This paper investigates three different strategies for centralized charging/discharging management of electric vehicles, their features and the impacts on technical performance of distribution systems. Three goals of load factor maximization, load variance reduction and energy loss minimization are chosen as the main technical factors need to be optimized in the proposed electric vehicles charging/discharging management strategies. In this regard, at first, the mathematical model of these strategies for both cases of with/without vehicleto- grid (V2G) programs are extracted. Then, solving procedure of the attained optimization problems with different optimization methods are explained. These...