1,721,530 research outputs found
다물체 동역학 기반 생체모방형 초소형 날갯짓 비행체의 동적 안정성 및 비행 제어
No full text학위논문(석사) - 한국과학기술원 : 항공우주공학과, 2021.8,[viii, 93 p. :]Since the demand for biomimetics-based aerospace systems is surging rapidly for the past few years, Flapping-wing Micro Air Vehicles (FWMAVs) are not an exception to these necessities. With the growing advancements in science and technology, scientists have realized that nature-inspired designs generally produce optimal solutions at minimal cost. One of the key bioinspired-based aerospace systems is an insect-like FWMAV that is considered quite impressive owing to its efficient flight utilizing complex aerodynamics. As real insects generally do the optimum flight, engineers are doing their best to explore the aerodynamics, kinematics, flight dynamics, and control to better mimic their flight. However, mimicking insects’ flight using FWMAVs has limited functionality considering the difficulty in understanding its complex aerodynamics and applying control.
Many studies have been conducted to characterize the stability of insect-like FWMAVshowever, they have limitations based on different areas such as the fidelity of the aerodynamic model, assumptions taken to modify the flight mechanics equations, wing kinematics adopted, rigid or flexible model used, and the type of trim search algorithm adopted. The present study considers a hawkmoth-scaled FWMAV model for characterizing its stability using a multibody dynamics simulation environment that involves fully coupled nonlinear equations of motion. The simulation environment incorporates a quasi-steady aerodynamic model, real and simplified hawkmoth wing kinematics and morphological data, kinematic constraints, and finally a gradient-based trim search algorithm. The complete simulation is run for five different speeds involving equal intervals from 0 to 1 m/s, and 6 Degrees of Freedom (6-DOF) stability is characterized based on it. The FWMAV model shows unstable behavior both in longitudinal and lateral directions (slightly damped) based on the results of the trim search.
The longitudinal direction instability is mainly related to the forward-backward direction velocities coupled with the pitching rate that results in unstable oscillatory modes. On the other hand, lateral instability augments as sideways velocity pairs with rolling and yawing rates. Firstly, the influence of body to wings mass ratio on longitudinal and lateral dynamic stabilities is investigated. Since longitudinal unstable oscillatory mode’s influence increases with speed, this study focuses on longitudinal motion control. LQR controller is implemented first to control the speed of linear FWMAV system using integral action. Next, the controller is implemented for 3-DOF motion control of the nonlinear model at five different speeds. Then, reference velocity profile tracking, involving hovering, acceleration, constant speed, and deceleration phases, is achieved for the non-linear model. Finally, various reference trajectories tracking is achieved by implementing a dual loop control technique.한국과학기술원 :항공우주공학과
Supplemental Material - Condiment Recipes Lead to Reduced Generation of Carcinogenic Polycyclic Aromatic Hydrocarbons in Duck Variety Meat During Charcoal Grilling
No full textSupplemental Material for Condiment Recipes Lead to Reduced Generation of Carcinogenic Polycyclic Aromatic Hydrocarbons in Duck Variety Meat During Charcoal Grilling by Gulshan Shahid, Muhammad Yousaf, Haseeb Anwar, Imran Mukhtar, and Abdul Basit in Dose-Response</p
sj-png-1-pie-10.1177_09544089221107991 - Supplemental material for Non-Newtonian power-law fluids with variable magnetic field and slip conditions
No full textSupplemental material, sj-png-1-pie-10.1177_09544089221107991 for Non-Newtonian power-law fluids with variable magnetic field and slip conditions by Muhammad Dawood, Muhammad Yousaf, Shafiq Ahmad and Salman Zeb in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p
sj-docx-2-chp-10.1177_2515690X221113327 - Supplemental material for Synergistic Effects of Natural Product Combinations in Protecting the Endothelium Against Cardiovascular Risk Factors
No full textSupplemental material, sj-docx-2-chp-10.1177_2515690X221113327 for Synergistic Effects of Natural Product Combinations in Protecting the Endothelium Against Cardiovascular Risk Factors by Muhammad Yousaf, Valentina Razmovski-Naumovski, Muhammad Zubair, Dennis Chang and Xian Zhou in Journal of Evidence-Based Integrative Medicine</p
The benefits of co-evolutionary Genetic Algorithms in voyage optimisation
No full textReducing emissions is of increasing global importance. Within shipping, the International Maritime Organisation's regulations are putting pressure on companies to quickly reduce emissions. One solution is the optimisation of a ship's route where even comparatively small reductions, in the order of 5%, provide sizeable cost and environmental benefits. The most recent advances from the Evolutionary Computation field have not been benchmarked on this problem, especially the co-evolutionary algorithms that provide the widest diversity of search. This paper compares state-of-the-art algorithms on three case studies, to show the impact of algorithm selection on the fuel consumption and expected voyage time. Four state-of-the-art Genetic Algorithms are selected to represent the leading families of Genetic Algorithm. The co-evolutionary approaches are shown to have the top performance, with cMLSGA (co-evolutionary Multi-Level Selection Genetic Algorithm) showing top performance on all the problems with the greatest potential reductions in fuel usage, 7.6% on average over the state of the art, and voyage times, 8.4% on average over the state of the art.</p
Supplementary_Information_of_scoparia_revised_updated – Supplemental material for Isolation and characterization of cytotoxic and anti-inflammatory constituents from Scoparia dulcis L
No full textSupplemental material, Supplementary_Information_of_scoparia_revised_updated for Isolation and characterization of cytotoxic and anti-inflammatory constituents from Scoparia dulcis L by Mohammad Nur-e-Alam, Sarfaraz Ahmed, Muhammad Yousaf, Shabana I Khan, Ramzi A Mothana and Adnan J Al-Rehaily in Journal of Chemical Research</p
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