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M. ESFAHANIAN,A. SAFAEI,H. NEHZATI,V. ESFAHANIAN,M. M. TEHRANI 한국자동차공학회 2014 International journal of automotive technology Vol.15 No.6
In this paper a package for designing, modelling and simulation of three hybrid powertrains are presented. These powertrains are Electric hybrid, Hydraulic hybrid and Flywheel hybrid. The differences among the proposed hybridpowertrains include the energy storage system components, the secondary power converter and also the powertrainconfiguration. The O457 city bus is considered as the benchmark vehicle. At first, the design process for each hybridpowertrain which is based on the power requirements of the bus in any driving condition is presented. Then, the powertrainsmodelling using MATLAB/Simulink as a powerful simulating tool is presented. The models are feed-forward and resemblethe real world driving conditions. Each model has the blocks for the main components of the corresponding propulsion system. The most important stage in the modeling process is implementing of the components efficiency in each powertrain. Moreover, there is a block in each hybrid powertrain model for the energy management. Finally, the simulation results forcomparing the usefulness of the hybrid powertrains are presented. The results indicate that the electric hybrid powertrain hasthe most effect on reducing the bus fuel consumption. But regarding the fabrication expenses and manufacturing complexity,the hydraulic hybrid powertrain is recommended.
Null broadened-deepened array antenna beamforming for GNSS jamming mitigation in moving platforms
Omid Sharifi-Tehrani,Mohamad F. Sabahi,M.R. Danaee 한국통신학회 2022 ICT Express Vol.8 No.2
Steering vector and covariance matrix estimation mismatch along with moving jammer/platform, can affect the performance of null-steering beamformer. In this paper, by utilizing null-widening, null-deepening and diagonal loading shrinkage in space–time adaptive processing (STAP) structure, two methods for nullifying GNSS (global navigation satellite system) jamming/interference in cruise moving platforms are introduced. The enhanced performance of the proposed methods is investigated through numerical simulations. The results indicate improvement in the number of acquired GNSS satellites, in heavy jamming (GNSS denied) scenario, by reconstructing and acquiring at least 87% of satellites.
GNSS Jamming Detection of UAV Ground Control Station Using Random Matrix Theory
Omid Sharifi-Tehrani,Mohamad F. Sabahi,M.R. Danaee 한국통신학회 2021 ICT Express Vol.7 No.2
Global navigation satellite systems (GNSS) are the main navigation and control systems in unmanned aerial vehicles (UAVs) and their ground control stations. Without the GNSS signals, the UAV and its ground control stations cannot follow the waypoints of the desired path in jamming environments. In this paper, two new methods for detection of GNSS signal jamming attack for UAV ground control station are proposed based on random matrix theory. By using limiting distribution of mean vector and asymptotic behavior of the defined test statistic, a hypothesis test is introduced and evaluated to detect presence of jamming signal. Simulation results show that the proposed methods have significant performance in terms of detection and false alarm probabilities. Compared to existing methods, at low jamming-to-signal ratio (JSR), more than 2.5 dB improvement is achieved.
FINITE ELEMENT ANALYSIS OF PROPORTIONAL SOLENOID CHARACTERISTICS IN HYDRAULIC VALVES
F. BAYAT,A. FADAIE TEHRANI,M. DANESH 한국자동차공학회 2012 International journal of automotive technology Vol.13 No.5
Proportional hydraulic valves (PHVs) have remarkable applications in different branches of industry. These valves can control an oil hydraulic system. One of the most important factors affecting a proportional solenoid (PS) is the geometry that affects its magnetic force with respect to its plunger position. Other effective factors include the size of the air gap, the current density and various soft magnetic materials that have different B-H (flux density versus field intensity) curves. Electromagnetic analysis (EMA) is used to enhance the reliability and accuracy of the PS and to reduce the total cost. In this paper, a range of PSs are software package with different air gaps, dimensional parameters, current densities and soft magnetic materials. The magnetic flux density and force are calculated using a finite element method (FEM), and the results are compared with the experimental results of an actual PS.
Application of Response Surface Methodology to Evaluate Stone Matrix Asphalt Stripping Potential
A. Khodaii,H. F. Haghshenas,H. Kazemi Tehrani,M. Khedmati 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.1
Stone matrix asphalt mixes are widely used in Western Europe due to its high strength properties in pavements, this type of mix is subjected to continuous wetting and drying cycles due to its porous structure leading to a higher potential for stripping. Lime has long been recognized and used in industry to reduce the stripping potential of SMA. Aggregate grading has also been identified to have an impact on the moisture damage potential. Response surface methodology was employed in this paper to evaluate the effect of lime content and grading on stripping potential of Stone Matrix Asphalt (SMA) using Tensile Strength Ratio (TSR) index. The statistical significances of linear, quadratic and interactive terms of the lime percent and grading were examined and second order polynomial regression equation was successfully fitted to the experimental results. The lime content of 1% and the finest aggregates resulted in a TSR optimum value of 91.8%±0.8%. It was further concluded that increasing the mastic asphalt would decrease the stripping potential of SMA and both of the two parameters evaluated, had approximately the same main effect on the TSR response.