| 12391. |
- Khodabakhshian, Mohammad, et al.
(författare)
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Fuel Saving Potential of Optimal Engine Cooling System
- 2014
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Konferensbidrag (refereegranskat)abstract
- The engine cooling system in trucks is one of the main sources of parasite load. Thus optimal control of the engine thermal management system with the objective of minimizing energy consumption can substantially improve fuel efficiency. Existing methods on the engine thermal control system concentrate mainly on regulating the engine coolant temperature within a safety range. This paper explicitly calculates the energy consumption of the cooling system using the optimal control methods to decide the trajectories of the control values of the cooling system. During the optimal operation, the engine cooling system serves as another energy buffer to balance the engine workload in conventional trucks. To expose the maximal fuel saving potential of the optimal engine thermal control system, we apply dynamic programming in the investigation and the results are compared with a simple state feedback controller.
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| 12392. |
- Khodabakhshian, Mohammad, et al.
(författare)
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Improvement of fuel efficiency and drivability using simple prediction for gear changing
- 2013
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 9783902823434 ; , s. 518-523
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Konferensbidrag (refereegranskat)abstract
- Decreasing fuel consumption and emissions in automobiles has been an active research topic in recent years. A promising technology is the hybridization of powertrain. The main focus in this area is usually on the development of optimal power management control methods. For parallel HEVs (hybrid electric vehicle), the primary control variable is the torque split between the internal combustion engine and the electric motor but gear number can also be considered as a control parameter. ECMS (equivalent consumption minimization strategy) is one of the well-known real time power management strategies and has been used extensively in different works; however, using ECMS for controlling gearbox cannot always lead to optimal fuel consumption and drivability. The slow dynamics of gearbox might introduce unnecessary gear changing, which leads to suboptimal fuel efficiency and degraded drivability. In this paper, a simple prediction strategy is implemented to improve fuel efficiency and drivability. The presented prediction method does not use any information from the environment and does not need any extra sensor. The strategy is not computationally heavy compared to other predictive methods. The simplicity of the method makes it suitable for implementations.
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| 12393. |
- Khodabakhshian, Mohammad, et al.
(författare)
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Predictive control of the engine cooling system for fuel efficiency improvement
- 2014
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Ingår i: Automation Science and Engineering (CASE), 2014 IEEE International Conference on. - : IEEE conference proceedings. ; , s. 61-66
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Konferensbidrag (refereegranskat)abstract
- The engine cooling system in trucks is one of the main sources of parasite load. Thus fuel efficiency can be improved by optimal control of engine thermal management system considering fuel consumption minimization as the objective. Although several optimal control methods have been proposed for the engine cooling system, their main emphasize is on regulating engine and coolant temperature in an acceptable range rather than minimizing fuel consumption. In contrast, this paper investigates the fuel saving potential of predictive optimal control methods for the engine cooling system of conventional trucks. Our method exploits the idea of energy buffers in the automotive system, where the engine cooling system and the battery serve as energy buffers. The advantages of this approach are the recovery of brake energy and the balance of energy sources so that the total energy loss is minimized. A model predictive controller is used as the real time controller, and the results are compared with a simple state feedback controller and a global optimal solution obtained by dynamic programming. The results show limited but notable improvement in fuel efficiency. The results also construct a base for ongoing research on energy buffer control in conventional heavy trucks.
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| 12394. |
- Khodabakhshian, Mohammad, et al.
(författare)
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Reducing Auxiliary Energy Consumption of Heavy Trucks by Onboard Prediction and Real-time Optimization
- 2017
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 188, s. 652-671
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Tidskriftsartikel (refereegranskat)abstract
- The electric engine cooling system, where the coolant pump and the radiator fan are driven by electric motors, admits advanced control methods to decrease auxiliary energy consumption. Recent publications show the fuel saving potential of optimal control strategies for the electric cooling system through offline simulations. These strategies often assume full knowledge of the drive cycle and compute the optimal control sequence by expensive global optimization methods. In reality, the full drive cycle is unknown during driving and global optimization not directly applicable on resource-constrained truck electronic control units. This paper reports state-of-the-art engineering achievements of exploiting vehicular onboard prediction for a limited time horizon and minimizing the auxiliary energy consumption of the electric cooling system through real-time optimization. The prediction and optimization are integrated into a model predictive controller (MPC), which is implemented on a dSPACE MicroAutoBox and tested on a truck on a public road. Systematic simulations show that the new method reduces fuel consumption of a 40-tonne truck by 0.36% and a 60-tonne truck by 0.69% in a real drive cycle compared to a base-line controller. The reductions on auxiliary fuel consumption for the 40-tonne and 60-tonne trucks are about 26% and 38%, respectively. Truck experiments validate the consistency between simulations and experiments and confirm the real-time feasibility of the MPC controller.
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| 12395. |
- Khodabandeh, Rahmatollah, et al.
(författare)
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Instability, heat transfer and flow regime in a two-phase flow thermosyphon loop at different diameter evaporator channel
- 2010
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311 .- 1873-5606. ; 30:10, s. 1107-1114
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the influence of different channel geometries on heat transfer, flow regime and instability of a two-phase thermosyphon loop, is investigated. Instabilities in flow regime and heat transfer, at low and high heat fluxes, are observed. Bubbly flow with nucleate boiling heat transfer mechanism, confined bubbly/slug flow with backflow for small channel height (H) and finally slug/churn flow at high heat fluxes are observed. This study shows that flow and thermal instability increases as channel height (H) decreases and also heat transfer coefficient increases with increasing channel height and heat flux. Bubbly flow characterizes the flow regime at high heat transfer coefficients while confined bubbles, backflow and intermittent boiling are more significant for low channel heights with lower heat transfer coefficient and critical heat flux. (C) 2010 Elsevier Ltd. All rights reserved.
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| 12396. |
- Khodabandeloo, Babak
(författare)
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Acoustical experiments on the non-linear and non-equilibrium behavior of rocks
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study of dynamic behavior of non-perfect materials, such as rocks, is a rich topic for developing sensitive material evaluation and damage detection techniques. It has extensive applications in a variety of fields such as Physics, Geology, and Aerospace, Mechanical, Civil, Petroleum, and Material Engineering. It is experimentally known that as the level of damage in any initially 'un-damaged' materials increases, their nonlinear elasticity increases considerably and their dynamic behavior becomes more similar to heterogeneous and micro-inhomogeneous materials such as rocks. Despite the diversity of inherently non-perfect materials, they share some common features, among them are fast nonlinear dynamics, slow dynamics and conditioning.In this thesis, the fast and slow dynamics, recovery and relaxation of geomaterials subjected to external influences such as ultrasound, heat and light are investigated experimentally. The effect of light on rock is monitored using two different material state indicator tests: the measurement of deflection of a granite beam; and, the changes in sound speed. Young's modulus variations for small temperature changes in granite, steel, brass, and graphite are measured, providing us with a quantitative base for separation of softening due to the temperature and to the ultrasonic field respectively.The resonance frequency dependence on amplitude of acoustic wave at temperatures from 15-60 Celsius was investigated. The effects of each of them (the temperature and the acoustic intensity) have been known separately, but here were conducted experiments to see their combined effects. The sound speed was monitored through the resonance frequency by a series of ultrasonic frequency sweeps with successively increasing amplitudes. There was in each temperature set surprisingly one - and only one - temperature at which the sound velocity increased with the ultrasound level. At all other temperatures the sound velocity decreased.In another test, the effect of ultrasonic activation of marble in a constrained boundary condition is studied experimentally for the first time. The observed effects indicate simultaneous expansion and softening of the rock when subjected to acoustic waves
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| 12397. |
- Khodadad, Davood, 1985-
(författare)
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Creating a supportive and effective learning environment for engineering students : Pedagogical strategies, engagement, and enhanced outcomes
- 2023
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Ingår i: International Journal of Engineering Pedagogy. - : International Association of Online Engineering. - 2192-4880. ; 13:8, s. 33-50
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Tidskriftsartikel (refereegranskat)abstract
- Engineering education requires a strong emphasis on problem-solving, critical thinking, and practical application of knowledge. To achieve the highest quality of teaching, educators must create a trusting environment that allows students to feel comfortable asking questions and performing to the best of their abilities. This paper outlines the teaching philosophy and prac-tices of an engineering lecturer who has adapted his pedagogical approach across several universities in Sweden and abroad. The author emphasizes the importance of being flexible and responsive to student needs, offering early and constructive feedback, and providing students a safe and supportive learning environment with opportunities to develop program-ming skills. The paper also includes comments from students that reflect the author’s effec-tiveness as an educator in creating a supportive and challenging learning environment for engineering students.
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| 12398. |
- Khodadad, Davood, 1985-
(författare)
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Digital holography for temperature investigations in space and transparent media
- 2023
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE.
-
Konferensbidrag (refereegranskat)abstract
- The paper presents a method for investigating temperature fields in space and transparent media using off-axis digital holographic interferometry. This interferometric technique is particularly well-suited for measuring dynamically changing temperature fields due to its capability to automatically evaluate temperature from a single interferogram. The experimental validation of this technique involved measuring temperature variations within a burning candle's flame. To establish a reference point, an initial hologram was captured without a burning candle, followed by subsequent holograms during the burning process. This allowed the observation of changing refractive index gradient states in the surrounding air. The reconstruction of the complex amplitude facilitated the calculation of the distribution of phase changes. By establishing a relationship between phase changes, thermal coefficients of the air's refractive index, and temperature fluctuations, temperature measurements were achieved at these distinct states. The accuracy of the measurement was estimated to be less than 1 °C in our experimental setup, showing the high precision achievable with this technique. In summary, the paper offers analysis of digital holographic interferometry as a tool for temperature measurements in transparent media. Its potential applications extend to combustion studies, space exploration, atmospheric research, and various other scientific disciplines.
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| 12399. |
- Khodadad, Davood, 1985-, et al.
(författare)
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Temperature Sensing in Space and Transparent Media : Advancements in Off-Axis Digital Holography and the Temperature Coefficient of Refractive Index
- 2023
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Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 13:14
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Tidskriftsartikel (refereegranskat)abstract
- An off-axis digital holographic interferometry technique integrated with a Mach–Zehnder interferometer based setup is demonstrated for measuring the temperature and temperature profile of a transparent medium. This technique offers several advantages: it does not require precise optomechanical adjustments or accurate definition of the frequency carrier mask, making it simple and cost-effective. Additionally, high-quality optics are not necessary. The methodology relies on measuring the phase difference between two digitally reconstructed complex wave fields and utilizing the temperature coefficient of the refractive index. In this way, we presented an equation of the temperature as a function of phase changes and the temperature coefficient of refractive index. This approach simplifies the calculation process and avoids the burden of complicated mathematical inversions, such as the inverse Abel transformation. It also eliminates the need for additional work with the Lorentz–Lorentz equation and Gladstone–Dale relation and can be extend for 3D measurements.
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| 12400. |
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