Showing 359 results for Type of Study: Research
Seyed Reza Hosseini, Mahdi Moghimi, Norouz Mohammad Nouri,
Volume 14, Issue 3 (9-2024)
Abstract
The impact of a supercooled droplet on a surface is a primary challenge of many industrial and aeronautical processes. However, in some cases, such as frost formation on vehicle windshields or wind turbine blades, the supercooled droplet collision does not occur in stagnant air. In this study, for the first time, the effects of the air transverse flow (ATF) on the thermal-fluid behavior of a supercooled droplet were investigated numerically. Also, different patterns of a superhydrophobic pillared surface were used in 24 three-dimensional simulations in ANSYS Fluent software. The volume of fluid method is chosen for the simulation of the multiphase flow. The freezing model is improved by the supercooling temperature consideration method. The results show that the ATF velocity reduces the separation time exponentially and helps the droplet bounce from the surface before freezing inception. However, the excessive increase in ATF velocity has the opposite effect and may prevent the droplet from detaching the surface due to notable drag. The best value of the ATF velocity is obtained to be 8 m/s , which reduces the separation time exponentially from 16.3 ms to 12.5 ms for a cold surface with a simple pillar pattern. The separation time is entirely affected by the simulation conditions and varies from 11.85 ms to 29.2 ms . The maximum spreading factor, despite the separation time, is seriously influenced by the void fraction percentage of different pillared surfaces and varies from 1.53 to 1.69.
Jamal Bidadi, Hamed Saeidi Googarchin,
Volume 14, Issue 3 (9-2024)
Abstract
Adhesively bonded joints are a highly effective method for achieving lightweight structural designs, yet assessing their long-term durability remains a significant challenge. Creep, a time-dependent effect caused by sustained mechanical loads, can result in viscous strain within adhesive materials, potentially leading to crack formation in bonded structures over extended periods. This study investigates the creep behavior of adhesive joints under sustained tensile loads, focusing on the effects of adhesive layer thickness and the presence of adhesive fillets. Creep tests conducted over 48 hours revealed that higher load levels result in greater strain accumulation, with thicker adhesive layers showing increased susceptibility to deformation. Additionally, joints with adhesive fillets demonstrated lower creep strain, indicating enhanced resistance to sustained loads. These findings emphasize the importance of adhesive layer thickness and fillet design in optimizing the long-term performance and durability of bonded joints, offering valuable insights for applications where creep resistance is critical for joint reliability and service life.
Mr Mehran Nazemian, Mr Mehrdad Nazemian, Mr Mahdi Hosseini Bohloli, Mr Hadi Hosseini Bohloli, Mr Mohammad Reza Hosseinitazek,
Volume 14, Issue 3 (9-2024)
Abstract
This study investigates the influence of nozzle hole diameter (NHD) variations on spray dynamics, combustion efficiency, and emissions in a Reactivity-Controlled Compression Ignition (RCCI) engine using Computational Fluid Dynamics (CFD) simulations with the CONVERGE software. The study systematically examines NHDs ranging from 130 µm to 175 µm and evaluates their impact on key parameters such as injection pressure, droplet formation, Sauter Mean Diameter (SMD), and evaporation rates. The results demonstrate that reducing NHD to 130 µm significantly enhances fuel atomization by reducing SMD to 15.49 µm and increasing droplet number by 24%, which in turn accelerates evaporation and improves fuel-air mixing. These effects shorten ignition delays, accelerate combustion, and increase peak cylinder pressures and temperatures. Optimal NHDs (150–160 µm) achieve the highest combustion efficiency (92.04%) and gross indicated efficiency (38.58%). However, further reduction in NHD below this range causes premature ignition, energy dissipation, and higher NOx emissions (10.08 g/kWh) due to elevated combustion temperatures. Conversely, when the NHD increases to 175 µm, the larger droplets formed result in prolonged ignition delays, slower combustion, and lower peak pressures. These effects negatively impact combustion efficiency and promote incomplete combustion, leading to higher HC (15.27 gr/kWh) and CO (4.22 gr/kWh) emissions. Larger NHDs, however, lower NOx emissions to 2.66 gr/kWh due to reduced peak temperatures. This study clearly identifies an optimal NHD range (150–160 µm) that effectively balances droplet size, evaporation rate, combustion timing, and emission reduction, thereby enhancing both engine performance and environmental sustainability.
Alireza Batooei, Ahad Amiri, Ali Qasemian,
Volume 14, Issue 4 (12-2024)
Abstract
One of the most important aspects of designing passenger cars is the engine cooling. This process would significantly affect the vehicle performance. This study has been conducted both theoretically and experimentally to reveal the influences of different involved parameters of cooling. The current research is implemented in order to examine the effects of 2-speed radiator fan utilization rather than the 1-speed type. For this aim, the new modified fan is considered and the experimental data are obtained to compare the results with those of the old one. Additionally, the effects of parameters such as ECU strategy, radiator fin density as well as the radiator plate geometrical properties are considered in the analysis. As a prominent result, the experimental results show a substantial effect of considering 2-speed radiator fan and choosing a better strategy for ECU on the cooling performance in the vehicle. The experimental results show that employing 2-speed fan instead of single-speed and 900 fin/m fin density instead of 780 fin/m decreases coolant outlet temperature of radiator by 6.1% and 7.1% in the same condition, respectively.
Reza Reza Azadavri, Somayeh Somayeh Mohammadi, Zeinab Zeinab Sanaee, Khadijeh Khadijeh Hooshyari,
Volume 14, Issue 4 (12-2024)
Abstract
This study explored the impact of Super P on the specific capacity of MXene-based rechargeable Li-O₂ batteries. It was found that increasing the Super P ratio from 10% to 30% significantly improved the specific discharge capacity of the lithium-oxygen battery, rising from 396 mAh g⁻¹ to 1116 mAh g⁻¹ during the first cycle at a current density of 100 mA g⁻¹. To characterize the structure of the synthesized MXene, analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy were utilized. The electrochemical performance of the fabricated electrodes was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The findings indicate that the synergistic interaction between MXene and Super P contributes to the enhanced capacity of the fabricated cell.
Bentolhoda Eivani, Hossein Moeinkhah, Saeed Farahat,
Volume 14, Issue 4 (12-2024)
Abstract
This paper presents an efficient dynamic programming method in order to examine the problem of optimal power management of hybrid electric vehicle (HEV) powertrains and compares its performance with a rule-based method. Since dynamic programming is a trajectory based optimization algorithm and provides a globally optimal solution, it can be used as a benchmark for assessment of other control strategies. However, a major limitation of this method is its extreme computational load which is known as the curse of dimensionality. The computation time and the memory requirements increase exponentially with the increase of states and inputs. In this paper, a novel approach is used to decrease the total computation load and shows how this improvement can provide more accurate results.
Mr Hossein Khalajzadeh, Dr Vahid Hosseini, Dr Alireza Shaterzadeh,
Volume 14, Issue 4 (12-2024)
Abstract
The engine mounting bracket is connected to the engine on one side and to the car body on the other side. The engine mounting bracket should be designed in such a way to prevent the transmission of vibrations from the body to the engine and vice versa. In addition, one of the tasks of the engine mounting bracket is to bear the weight of the engine and the dynamic and vibrational loads caused by the movement of the car on the road. The engine mounting bracket are generally designed in such a way that they have sufficient fatigue life in a defined range of cyclic forces and fail in the range of high forces caused by an accident in order to minimize the level of damage to the vehicle and passengers. This research will investigate the effect of manufacturing parameters on the fatigue behavior of the aluminum engine mounting bracket. High-cycle fatigue test was taken from the prototypes and based on the results of this test, the prototype was considered unsafe. Therefore, in order to improve the produced part, by removing the factors that cause weakness in the part and strengthening the area in front of the engine mounting bracket, the secondary sample of the engine mounting bracket was produced, but due to the high costs of re-fatigue testing, radiographic test was done of the reinforced areas before testing. Then, fatigue test was taken from the secondary sample. The test results of the modified sample were within the acceptable range.
Mr. Mohammad Hossein Nahani, Dr. Gholam Reza Molaeimanesh, Dr. Masoud Dahmardeh,
Volume 14, Issue 4 (12-2024)
Abstract
The transition from traditional internal combustion engine vehicles to electric vehicles is in progress. With their high energy density, low self-discharge rates, long cycle life, and absence of memory effects, lithium-ion batteries have become the primary power source for alternative vehicles. Throughout the battery's lifespan, its performance or health gradually deteriorates due to irreversible physical and chemical changes. Depending on the specific aging mechanisms, a battery may lose capacity or face increased internal resistance. Growing awareness of the importance of environmental protection and the potential implications associated with products and services has spurred interest in developing methods to better understand and address these impacts. Life cycle assessment is a method used to examine the environmental effects associated with all stages of product production. This study compares the operational conditions of an electric vehicle equipped with both new and old battery packs. The performance difference indicates that the vehicle with the aged battery has 17% less capacity, operates over 20% weaker in range, and its ohmic resistance increases by up to 150%. From a well-to-wheel perspective, using an electric vehicle with an old battery could result in a 2% increase in carbon dioxide emissions, reaching 56.638 g CO₂ equivalent per kilometer.
Hojjat Saberinejad,
Volume 15, Issue 1 (3-2025)
Abstract
One of the main challenges in designing a vehicle's cooling system, particularly the radiator, is not considering the non-uniform airflow distribution in the radiator's characteristic performance graphs. In this study, a three-dimensional numerical analysis of the airflow passing through a QUIK vehicle and the effect of the cooling system's placement relative to the vehicle's grille in five different cases was conducted. The effect of non-uniform airflow distribution on related radiator parameters such as the Darcy number, particle diameter, and inertial term was examined. The results indicate that the optimal placement range of the vehicle's cooling system for appropriate cooling performance is very limited. Additionally, non-uniform air velocity distribution plays a significant role in the radiator pressure drop. The inertial term is more significant in non-uniform flow conditions. For larger Forchheimer numbers, the change in radiator pressure drop for uniform compared to non-uniform flow distributions is about 22%.
Alireza Goharian, Alireza Asadolahei,
Volume 15, Issue 1 (3-2025)
Abstract
This study investigates the effects of ozone gas injection on reducing exhaust emissions in internal combustion engines (ICEs). Ozone (O₃), a highly reactive oxidizing agent, has been widely utilized for air and water purification. Its ability to break down pollutants makes it a promising alternative or supplement to conventional catalytic converters, which require expensive materials and periodic recycling. In this research, ozone gas was generated using the corona discharge method and injected into the combustion system to evaluate its impact on carbon monoxide (CO) emissions. A low-power 12-volt compressor, capable of producing up to 10 bar pressure, was used to ensure proper injection. A five-gas analyzer was employed to measure emission changes before and after ozone injection. Results indicated an average CO reduction of 34–40% across seven tested vehicles, with the highest effectiveness observed at steady-state engine operation and moderate loads. Furthermore, an increase in lambda (λ) values suggested improved air-fuel combustion efficiency. Statistical analysis, including standard deviation (±0.005) and a 95% confidence interval, confirmed the reliability of these findings. The results demonstrate that ozone injection can serve as a cost-effective method to supplement traditional emission control technologies, potentially reducing reliance on catalytic converters.
Mr. Pooriya Sanaie, Dr. Morteza Mollajafari,
Volume 15, Issue 1 (3-2025)
Abstract
Electric Power Steering (EPS) systems are increasingly being integrated into modern vehicles, offering enhanced fuel efficiency and improved maneuverability. However, these systems are often subject to noise and disturbances, which can significantly impact steering precision and driver comfort. Addressing these challenges requires the implementation of robust control strategies capable of mitigating noise and disturbances in EPS systems. This paper explores advanced methods for achieving robust control in Electric Power Steering systems by reducing noise interference and countering external disturbances. Key techniques involve adaptive control algorithms and robust filtering mechanisms that maintain system stability and performance even under variable operating conditions. Experimental results demonstrate that these robust control approaches effectively minimize noise levels and disturbance impacts, leading to smoother steering response and greater reliability. This study underscores the critical role of robust control in enhancing the functionality and safety of Electric Power Steering systems while highlighting the intricate dynamics between noise, disturbances, and control system robustness in automotive applications.
Ashkan Moosavian, Mojtaba Mehrabivaghar, Mani Ghanbari,
Volume 15, Issue 1 (3-2025)
Abstract
Mr Mahdi Keyhanpour, Ms Fatemeh Sadat Mirabedini, Prof Majid Ghassemi,
Volume 15, Issue 1 (3-2025)
Abstract
This study develops and validates a simplified testing methodology aligned with UNECE Regulation No. 49 to quantify particle number (PN) emissions from diesel vehicles. A modified World Harmonized Vehicle Cycle (WHVC) was implemented, incorporating steady-state operational segments (urban: 21.3 km/h, rural: 43.6 km/h, motorway: 76.7 km/h), and applied to evaluate 51 Iranian-manufactured diesel vehicles. The tested fleet comprised heavy-duty trucks, buses, and pickup trucks equipped with diverse propulsion systems (e.g., ISF3.8s5154, OM457LA.IV) and after-treatment technologies, including SCR, DOC, and DPF. Results demonstrate that original equipment manufacturer (OEM)-installed DPFs reduced PN emissions by 7000-fold compared to non-DPF-equipped vehicles (2.49 × 10¹⁰ vs. 1.74 × 10¹⁴ particles/km; p < 0.001). Euro VI-compliant vehicles exhibited the lowest emissions (6.01 × 10¹⁰ particles/km), outperforming Euro V and Enhanced Environmentally Friendly Vehicle (EEV) standards. These findings underscore the necessity of adopting OEM-grade filtration systems and enforcing stringent emission regulations, such as Euro VI, to mitigate particulate pollution in urban environments. The methodology provides a replicable framework for emerging markets to align with global emission compliance protocols.
Ehsan Vakili, Behrooz Mashadi, Abdollah Amirkhani,
Volume 15, Issue 1 (3-2025)
Abstract
Ensuring that ethically sound decisions are made under complex, real-world conditions is a central challenge in deploying autonomous vehicles (AVs). This paper introduces a human-centric risk mitigation framework using Deep Q-Networks (DQNs) and a specially designed reward function to minimize the likelihood of fatal injuries, passenger harm, and vehicle damage. The approach uses a comprehensive state representation that captures the AV’s dynamics and its surroundings (including the identification of vulnerable road users), and it explicitly prioritizes human safety in the decision-making process. The proposed DQN policy is evaluated in the CARLA simulator across three ethically challenging scenarios: a malfunctioning traffic signal, a cyclist’s sudden swerve, and a child running into the street. In these scenarios, the DQN-based policy consistently minimizes severe outcomes and prioritizes the protection of vulnerable road users, outperforming a conventional collision-avoidance strategy in terms of safety. These findings demonstrate the feasibility of deep reinforcement learning for ethically aligned decision-making in AVs and point toward a pathway for developing safer and more socially responsible autonomous transportation systems.
Dr Milad Badri Kouhi, Dr Behrooz Mashadi,
Volume 15, Issue 2 (6-2025)
Abstract
A new idea is applied for damping of driveline oscillation (shunt and shuffle) created because of sudden changes in transmitting engine torque. In this case, by an actuator the dry clutch slides due to decreasing in clutch clamp force. By regulating the clutch force, it prevents the excessive torque from entering the driveline, which causes vibrations. This strategy eliminates the oscillations. Hence, the driveline dynamics which consists of the clutch model, driveline elements, backlash, and tire slip is modeled comprehensively in the MATLAB software and validated. When the vibrations are sensed by sensors, the electronic control unit directs the clutch actuator by changing the normal clutch force so the dry clutch slides and dampens the vibrations. For this idea, three controlling approaches are suggested: a rule-based controller, a pulse controller, and a linear predictive controller. Essential tests for examining driveline control performance are chosen and then the driveline performance is assayed for it. Also, one of the priorities in selecting a clutch control strategy is to increase the clutch lifetime. From the results, driveline vibrations including shunt and the shuffle can be reduced well. In addition, this idea doesn’t have the harms of the other solutions such as spark advance engine control that pollutes the air and electronic throttle control which lessens the vehicle performance. Moreover, the usage of this system is simple, especially in vehicles that have automatic manual transmission.
Davod Molaei, Dr. Mostafa Talebitooti,
Volume 15, Issue 2 (6-2025)
Abstract
This paper presents a novel investigation into the free vibration of porous folded plates using the differential transformation method (DTM). The porosity is functionally graded (FG) along the thickness of the plate, resulting in material properties that vary with the z-coordinate. The motion equations for each plate segment are derived based on classical plate theory (CPT), with simply-supported boundary conditions applied at the front edges, allowing the transformation of partial differential equations into ordinary differential equations. The differential transformation method is then employed to discretize the motion equations in the x-direction. By applying boundary conditions at the remaining edges and ensuring continuity at the joints, the eigenvalue problem is formulated, leading to the calculation of natural frequencies and mode shapes of the folded plate. The mathematical model is validated through comparisons with finite element method (FEM) results and existing literature. Results indicate that Type C porosity distributions exhibit the highest stiffness and resonant frequency compared to other porosity types. While frequency behavior is consistent across mode numbers regardless of porosity distribution and plate length, the impact of the porosity parameter on the frequency of Type C plates is demonstrably less significant than on other porosity types.
Mr Mehran Nazemian, Mr Mehrdad Nazemian,
Volume 15, Issue 2 (6-2025)
Abstract
This study investigates the performance of Reactivity-Controlled Compression Ignition (RCCI) engines under varying engine speeds using a 4E approach (Evaporation, Energy, Emissions, Exergy) and introduces innovative multidimensional efficiency indices. A 1.9-liter TDI Volkswagen engine was modeled in CONVERGE CFD software to analyze spray dynamics, combustion processes, and emissions across different engine speeds. New indices, including Evaporation-Energy Performance Index (EvEPI), Emission-Energy Synergy Index (EmESI), and Exergy-Emission Balance Index (ExEmBI), were developed to evaluate engine performance comprehensively. Results reveal that optimal performance occurs within 1600–2200 RPM, where fuel evaporation, combustion efficiency, and exergy utilization are maximized while emissions are minimized. For instance, at 3100 RPM, EvEPI increases sharply to 9857.17 mg/ms, reflecting enhanced evaporation but also highlighting risks of non-uniform fuel-air mixing at high speeds. Conversely, EmESI for HC rises from 33.04 gr/kW.h at 1000 RPM to 284.90 gr/kW.h at 3100 RPM, indicating increased unburned hydrocarbons due to incomplete combustion. NOx emissions decrease from 11.51 gr/kW.h at 1600 RPM to 2.28 gr/kW.h at 3100 RPM, aligning with reduced combustion temperatures. Higher speeds lead to elevated HC and CO emissions due to shorter mixing times, while lower speeds increase NOx due to prolonged combustion durations. Exergy analysis shows total and second-law efficiencies peak at lower speeds, emphasizing the importance of optimizing operational parameters. These findings provide valuable insights for designing efficient, low-emission RCCI engines.
Dr. Alireza Sobbouhi, Mohammad Mozaffari,
Volume 15, Issue 2 (6-2025)
Abstract
The high penetration of renewable energy sources (RES) makes the power system unreliable due to its uncertain nature. In this paper, the quantifying impact of electric vehicles (EV) charging and discharging on power system reliability and relieving the congestion is analyzed. The proposed reliability assessment is formulated by considering generation and demand interruption costs for N-1 contingency criteria. The proposed algorithm manages the optimal scheduling of EV to mitigate the uncertainties associated with RES and relieving the congestion. The impact of EV charging and discharging on expected energy not supplied (EENS) and expected interruption cost (ECOST) for generating companies (GENCOs), transmission companies (TRANSCOs), customers, and entire power system are calculated. The charging station of EV is selected by the trade-o_ between investment cost of EV and percentage change in EENS and ECOST value for the entire power system, GENCOs, TRANSCOs, and customers. The effectiveness of the proposed approach is tested on the modified IEEE RTS 24 bus system. The impact of EV charging stations on system reliability has been evaluated by quantifying the EENS and the ECOST across all available EV capacities. The results clearly demonstrate the improvement of system reliability and minimize the objective function consisting of generator re-dispatch and load curtailment considering N-1 contingency in the face of uncertainties of wind and solar generation sources by considering EV. The results show that EV can improve the reliability by about 40%. The problem is modeled in GAMS environment and solved using CONOPT as a nonlinear programming (NLP) solver.
Mrs Nayereh Raesian, Dr. Hossein Gholizadeh Narm,
Volume 15, Issue 2 (6-2025)
Abstract
Emergency braking during cornering is one of the main challenges in vehicle dynamics. This paper proposes a novel parallel control architecture for Electro-Hydraulic Braking (EHB) systems that dynamically balances the priorities of Emergency Braking (EB) and Electronic Stability Control (ESC) using a fuzzy-GA optimizer. . The proposed approach achieves significant improvements in yaw stability without compromising deceleration performance. The proposed control structure consists of two parallel branches that adjust the required pressure for each wheel and uses two inputs: the steering angle and the position of the driver's foot on the brake pedal. The control system is structured in such a way that it simultaneously calculates the vehicle deviation value using the sliding mode controller and then determines the appropriate pressure to compensate for this deviation, while at the same time estimating the appropriate brake pressure based on the brake pedal input. To effectively apply these inputs to the vehicle braking system this paper introduces an innovative approach that uses a fuzzy controller optimized through a genetic algorithm.
Mohsen Karmozdi,
Volume 15, Issue 2 (6-2025)
Abstract
The liquid metal droplets in the mercury magnetic reciprocating micropump are actuated by Lorentz force and reciprocated inside some sub-channels. The droplets in sub-channel act as pistons to pump the working fluid. The initial step in establishing the performance of the mercury magnetic reciprocating micropumps is to study the motion of droplet inside the channel. The extraction of the analytic equation governing the droplet motion inside the channel is complicated due presence of electromagnetic fields and three dimensional effects of the flow. Further, the existence of a pumped fluid in contact with the droplet and the adhesion force due to small dimensions are considered as the other reasons. In this study, the forces operating on the droplet were figured out by the Lagrangian approach and lumped mass assumption for the droplet. Accordingly, forces less than 5% of the actuation force were eliminated from the motion equation of droplet employing dimensional analysis. The simplified equation was presented as an ordinary differential equation and solved numerically. In addition to the analytic solution, the issue was experimentally investigated for a case study. The analytic and empirical results accord well with one another. The method pointed out in this study can be applied to predict the droplet motion in various microsystems.
