Model-Based Development and Evaluation of Control for Complex Multi-Domain Systems: Attitude Control for a Quadrotor UAV

A Cyber-Physical System (CPS) incorporates sensing, actuating, computing and communicative capabilities, which are often combined to control the system. The development of CPSs poses a challenge, since the complexity of the physical system dynamics must be taken into account when designing the control application. The physical system dynamics are often defined within mechanical and electrical engineering domains, with the control application residing in software and control engineering domains. Therefore, such a system can be considered multi-domain.With the constant increase in the complexity of such systems, caused by technological advances in all domains, new ways of approaching multi-domain system development are needed. One methodology, which excels in complexity management, is model-based development. Multidomain systems require collaborative modeling, where the physical system dynamics are captured in the Continuous Time (CT) modeling domain and the digital control is captured in the Discrete Event (DE) modeling domain.This thesis demonstrates how an extended CT-first model-based development approach can be applied to a complex multi-domain system. A collaborative model of a quadrotor Unmanned Aerial Vehicle (UAV) has been constructed and used to develop an attitude controller based on Model Predictive Control (MPC). The MPC controller has been compared to an existing open source Proportional Integral Derivative (PID) attitude controller.This thesis contributes to the discipline of model-based development with a methodological extension to the CT-first approach, which extends the conventional approach by expanding the physical modeling process into three consecutive steps. An evaluation of the extension is presented, describing how and when the extended methodology provides increased value

Determination of Noise Caused by Ventilated Brake Disc with Respect to the Rib Shape and Material Properties Using Taguchi Method

Ventilated brake discs may have various configurations of ribs and can be manufactured from different materials. In order to improve the performance in extreme exploitation conditions, it is necessary that they heat up and wear as little as possible, and that they have good heat dissipation capacity and generate low noise. To achieve this, optimization of the influential parameters is required. In this study, the optimization and the analysis of the frequency value were made on the basis of the influential parameters, such as brake disc vane shape, density, Young’s modulus, and Poisson\u27s coefficient. A numerical investigation was conducted using the ANSYS software package in the MODAL module. In order to better understand which parameter has the greatest influence on the noise formation, the Taguchi method was applied. By applying the Analysis of Variance – ANOVA, the influence of each parameter on frequency, expressed as a percentage, was determined. The obtained results show that the most influential parameter is the shape of the ribs (90.82%), followed by Young’s modulus (8.26%) and density (0.89%)

Numerical Analysis of IC Engine Operation with High-Pressure Hydrogen Injection

The limited quantities of oil reserves and the exhaust emissions from IC engines have become a threat to the existence of IC engines. One of the best solutions to the problem is the use of alternative fuels. Hydrogen is an alternative fuel that is called a fuel of the future. A disadvantage of hydrogen is its high combustion speed. Experimental results were used for the determination of inputs for numerical analysis. The numerical analysis is performed for a 3D model of the engine in order to determine the working parameters of the engine (pressure and temperature). The main goal of this study is to investigate a possibility of modifying the diesel engine so that it can run on hydrogen. It was found that in such an engine the greatest loads occur in the combustion chamber; thus, the vital parts of the engine are protected. Therefore, a mechanical analysis of the combustion chamber was performed (calculation of stresses and deformations). The obtained results are encouraging because they indicate that by applying the presented solution a much cheaper technology than the modern diesel engine systems is made possible

Contributions of mean and shape of blood pressure distribution to worldwide trends and variations in raised blood pressure: A pooled analysis of 1018 population-based measurement studies with 88.6 million participants

© The Author(s) 2018. Background: Change in the prevalence of raised blood pressure could be due to both shifts in the entire distribution of blood pressure (representing the combined effects of public health interventions and secular trends) and changes in its high-blood-pressure tail (representing successful clinical interventions to control blood pressure in the hypertensive population). Our aim was to quantify the contributions of these two phenomena to the worldwide trends in the prevalence of raised blood pressure. Methods: We pooled 1018 population-based studies with blood pressure measurements on 88.6 million participants from 1985 to 2016. We first calculated mean systolic blood pressure (SBP), mean diastolic blood pressure (DBP) and prevalence of raised blood pressure by sex and 10-year age group from 20-29 years to 70-79 years in each study, taking into account complex survey design and survey sample weights, where relevant. We used a linear mixed effect model to quantify the association between (probittransformed) prevalence of raised blood pressure and age-group- and sex-specific mean blood pressure. We calculated the contributions of change in mean SBP and DBP, and of change in the prevalence-mean association, to the change in prevalence of raised blood pressure. Results: In 2005-16, at the same level of population mean SBP and DBP, men and women in South Asia and in Central Asia, the Middle East and North Africa would have the highest prevalence of raised blood pressure, and men and women in the highincome Asia Pacific and high-income Western regions would have the lowest. In most region-sex-age groups where the prevalence of raised blood pressure declined, one half or more of the decline was due to the decline in mean blood pressure. Where prevalence of raised blood pressure has increased, the change was entirely driven by increasing mean blood pressure, offset partly by the change in the prevalence-mean association. Conclusions: Change in mean blood pressure is the main driver of the worldwide change in the prevalence of raised blood pressure, but change in the high-blood-pressure tail of the distribution has also contributed to the change in prevalence, especially in older age groups

k-Graphlet Counting in Degree Bounded Graphs

An enumeration algorithm for efficient k-graphlet enumeration and counting based on Binary Space Partitioning technique. The algorithm works on all the input graphs but performs quite efficiently on graphs that have bounded degree, i.e. all the nodes do not exceed a fixed maximum degree d

The Influence Of The Hydrogen Injection Timing On The Internal Combustion Engine Working Cycle

From an ecological aspect, the hydrogen has all properties to be a very good fuel for internal combustion engines. However the high combustion speed, as well as the possibility of backfire, is inconvenient properties of port injection. In this paper, the influence of the injection timing on the internal combustion engine working cycle parameters (pressure and temperature) was investigated deeply. The investigation, of the injection timing influence on the internal combustion engine working cycle parameters, was performed numerically by application of ANSYS software. It was observed the geometry of the real engine with added pre chamber, in order of layer mixture formation and pressure damping, because of high combustion speed. The results are presented for four cases with different injection timing and the same spark timing. By earlier injection, the time for mixing rise as well as the possibility of homogenization and uniform mixture creation, in pre chamber and cylinder. This claim it is confirmed on the basis of obtaining pressure and pressure rise gradient, which are growing with earlier injection, because of hydrogen combustion characteristics in stoichiometric mixture. The higher pressures as well as the surface under the diagram are positive from the aspect of the engine efficiency. However, with the earlier injection, the values of the pressure rise gradient are higher than for the classic Diesel engine. This means that this phenomena can cause brutal engine work from the aspect of mechanical stresses. However the value of the maximum pressure is smaller than this in a Diesel engine, this is due to added pre chamber, which has decreased the compression ratio