ALESSANDRO GERLINGER ROMEROLUIZ CARLOS GADELHA DE SOUZA
8页
查看更多>>摘要：In 2013, the STRaND (University of Surrey and Surrey Satellite Technology Ltd) and the PhoneSat (NASA) programs attracted the attention of the aerospace community applying commercial off-the-shelf smart-phones in CubeSats. Both programs deployed CubeSats using smartphones based on Google's Android, in which application development is mainly based on Java programming language. Some of these CubeSats had actuators, e.g., STRaND-1 had three reaction wheels mounted in an orthogonal configuration to provide three-axis control, whereas PhoneSat 2.0 beta had magnetorquers to de-tumble the spacecraft. Taking into account a CubeSat that runs Android operating system (based on a smartphone), it is natural to evaluate the attitude and orbit control subsystem (AOCS) based on Java. Elsewhere, we shown State-Dependent Riccati Equation (SDRE) is a feasible non-linear control technique that can be applied in such CubeSats using Java. Moreover, we shown, through simulation using a Monte Carlo perturbation model, SDRE provides better performance than the PID controller, a linear control technique. In this paper, we tackle the next fundamental problem: stability. We evaluate stability from two perspectives: (1) parametric uncertainty of the inertia tensor and (2) a Monte Carlo perturbation model based on a uniform attitude probability distribution. Through the combination of these two perspectives, we grasp the stability properties of SDRE in a broader sense. In order to handle the uncertainty appropriately, we combine SDRE with H_∞. The Nanosatellite Constellation for Environmental Data Collection (CONASAT), a CubeSat from the Brazilian National Institute for Space Research (INPE), provided the nominal parameters for the simulations. The initial results of the simulations shown that the SDRE controller is stable to ± 20% uncertainty in the inertia tensor for attitudes uniformly distributed and angular velocity up to 0.15 radians/second.
查看更多>>摘要：Power system stabilizer (PSS) is used to damping power system local and interarea modes of oscillation. It will act as additional signal through the generator excitation system which produces a component of electrical torque in phase with speed variation. Fuzzy controller is nonlinear. It is more difficult to set the fuzzy controller gains compared to conventional PID controller. This research proposed velocity (PID-FPSS) its gains are tuned off-line by particle swarm optimization techniques (PSO). The objectives are to damp local-area mode of oscillations that occur following power system disturbances. The effectiveness of the proposed technique is illustrated by applying the velocity PID-FPSS to a single-machine infinite bus power system that is typically used in the literature to test the performance of power system stabilizers. The simulation studies has been tested in MATLAB SIMULINK package. A comparison between the proposed PID-FPSS and a well-tuned and designed robust power system stabilizer (RPSS) confirms the superiority of the PID-FPSS.
查看更多>>摘要：This article presents a review of the most relevant manual techniques and technologies developed from the field of artificial vision aimed at identifying biomechanical alterations. The purpose is to describe the most important aspects of each technology, focused on the description of each of its stages and experimental results, which suggest the integration of mobile devices with artificial vision techniques, in addition to the different computer programs used for such end. Finally, the results showed that the identification of the crook index for alterations in posture turns out to be a technique currently used by most specialists. The great challenge is to develop portable devices through mobile applications that allow the detection of the corvo index and the barometric analysis, as well as for other types of applications that depend on visual analysis by experts.
查看更多>>摘要：The paper considers the system of automatic control of the tunnel kiln temperature conditions. The investigation of a delay influence on the transition process has been carried on. The transfer function of the object under control with interval coefficients taking into account possible effects of the parametric uncertainty has been obtained. A graphical method of representing the obtained results in the form of displaying the modified amplitude-phase characteristics on a complex plane has been applied which obviously demonstrates a robust absolute stability of the system under investigation. The simulation performed in the Matlab environment has proved the correctness of the results obtained.
查看更多>>摘要：The purpose of this research is to conduct aerodynamics study and design a hybrid drone system of fixed-wing and multi-copter. The mission of this drone is to measure human body temperature during COVID-19 pandemic. The specific aim of the drone is to fly and cover larger industrial areas roughly about 50 km~2 with longer flying time than the conventional drone, of about 1.5 hours. The applications of the simulation software such as XFLR5 and ANSYS have a big impact in identifying areas that need to be improved for the drone system. XFLR5 software was used to compare the characteristics of different airfoils with highest lift over drag, L/D ratio. Based on the airfoil selection, it was found that NACA 4412 airfoil produces the highest L/D ratio. The detailed geometry of the drone system includes a fuselage length of 1.9 meters and wingspan of 2 meters. Moreover, 10 sheets of solar panels were placed along the wing for sustainable flight operation to cover wider areas of mission. The structural analysis was done on ANSYS to test the elastic stress, equivalent strain, deformation, factor of safety pressure as well as lift and drag forces under various operational conditions and payloads. The landing gear was analyzed for harsh landing. ANSYS Computational Fluid Dynamics (CFD) was utilized to study the aerodynamics of the drone at different parameters such as the velocities and angles of attack during the operation. This design ensures the stability of the drone during the temperature measurement phase. The best thermal-imaging camera for such purpose would be the Vue Pro R 336, 45° radiometric drone thermal camera with a resolution of 640 x 512 pixels. This camera has the advantage of a permanent continuous out focus that give the ability of taking measurements even if there was changing on the altitude or any kind of vibrations.
查看更多>>摘要：We demonstrate that suitable initial conditions exist for a particle motion along a curved path, like a circle, without any external forces acting on it. This we achieve by diverting from the popular practice of describing motions of macroscopic bodies through Newtonian mechanics, and instead opt for quantum mechanics. This we do for the hydrogen atom. The validity of the idea is demonstrated by presenting a formula for G, the universal gravitational constant.
查看更多>>摘要：The problem of designing a controller to achieverobust stability and asymptotic tracking despite certain disturbancesis considered for linear time-invariant descriptortypeneutral time-delay systems. The necessary and sufficientconditions for the solvability of this problem are derived. Inthe case a solution exists, the structure of the controller whichsolves this problem is also presented.
查看更多>>摘要：This paper describes a simple digital temperature control system where the popular LM35DZ sensor is used to sense the temperature of a resistive heating element and to provide a feedback to an Arduino microcontroller board. By subtracting the measured temperature from the desired temperature, a value of error is then processed by a conventional PID controller which provides an adjustment signal and drives a bipolar junction transistor in order to minimize or remove that error by a simple ON/OFF switching of the power to the heating element. The control is also done using logic controllers such as ON/OFF and hysteresis controllers. The evaluation of each controller performance is based on rise time, overshoot, steady state error and the most common performance criterion which is the integral of the absolute value of the error. Besides that, the arduino integrated development environment (IDE) software is used to write the program code. Moreover, other languages are used to program the Arduino such as Matlab support package for Arduino hardware, Flowcode IDE and mBlock.
Abdulla Khamis AlhassaniMohanad Tarek MohamedMohammed FaresSharul Sham Dol...
9页
查看更多>>摘要：The supersonic combustion scramjet in the inlet applies the shock waves compression mechanism to substitute the actual compressor from a gas turbine engine. The scramjet works with combustion of fuel through the air stream in supersonic condition at least with Mach 5. Novel design of a scramjet intake system was made with variations in the angle of the fins and entrance width. The best combination of diameter and inclination angle was 1.75 m and 15 degrees, respectively. The findings were able to increase the oblique shock wave interactions and supplicate effective combustion and reduce pressure losses for the effective application of scramjet system.
查看更多>>摘要：Lie Point symmetries and Euler's formula for solving second order ordinary linear differential equations are used to determine symmetries for the one-dimensional Black-Scholes equation. One symmetry is utilized to determine an invariant solutions.
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