An approach to the automatic synthesis of controllers with mixed qualitative/quantitative specifications.

The world of systems and control guides more of our lives than most of us realize. Most of the products we rely on today are actually systems comprised of mechanical, electrical or electronic components. Engineering these complex systems is a challenge, as their ever growing complexity has made the analysis and the design of such systems an ambitious task. This urged the need to explore new methods to mitigate the complexity and to create simplified models. The answer to these new challenges? \textit{Abstractions}. An abstraction of the the continuous dynamics is a \textit{symbolic model}, where each ``symbol'' corresponds to an ``aggregate'' of states in the continuous model. Symbolic models enable the \textit{correct-by-design} synthesis of controllers and the synthesis of controllers for classes of specifications that traditionally have not been considered in the context of continuous control systems. These include \textit{qualitative} specifications formalized using temporal logics, such as \acf{LTL}. Besides addressing qualitative specifications, we are also interested in synthesizing controllers with \textit{quantitative} specifications, in order to solve optimal control problems. To date, the use of symbolic models for solving optimal control problems, is not well explored. This MSc Thesis presents a new approach towards solving problems of optimal control. Without loss of generality, such control problems are considered as path-planning problems on finite graphs, for which we provide two shortest path algorithms; one deterministic \acf{SDSP} algorithm and one non-deterministic \acs{SDSP} algorithm, in order to solve problems with quantitative specifications in both deterministic and non-deterministic systems. The fact that certain classes of qualitative specifications result in the synthesis of (maximally-permissive) controllers, enables us to use the \acs{SDSP} algorithms to also enforce quantitative specifications. This, however, is not the only path towards our goal of synthesizing controllers with mixed qualitative-quantitative specifications; it is possible to use the \acs{SDSP} algorithms directly to synthesize controllers for the same classes of specifications. Finally, we implement the algorithms as an extension to the \texttt{MATLAB} toolbox \texttt{Pessoa}, using Binary Decision Diagrams (BDDs) as our main data structure.Embedded SystemsDelft Center for Systems and ControlMechanical, Maritime and Materials Engineerin

Formation and chemical aging of secondary organic aerosol during the β-caryophyllene oxidation

The secondary organic aerosol (SOA) production during the oxidation of &beta;-caryophyllene by ozone (O₃) and hydroxyl radicals (OH) and the subsequent chemical aging of the products during reactions with OH were investigated. Experiments were conducted with ozone and with hydroxyl radicals at low NO_<i>x</i> (zero added NO_<i>x</i>) and at high NO_<i>x</i> (hundreds of parts per billion). The SOA mass yield at 10 μg m⁻³ of organic aerosol was 27% for the ozonolysis, 20% for the reaction with OH at low NO_<i>x</i>, and 38% at high NO_<i>x</i> under dry conditions, 20 °C, and ozone excess. Parameterizations of the fresh SOA yields have been developed. The average fresh SOA atomic O : C ratio varied from 0.24 to 0.34 depending on the oxidant and the NO_<i>x</i> level, while the H : C ratio was close to 1.5 for all systems examined. An average density of 1.06 ± 0.1 μg m⁻³ of the β-caryophyllene SOA was estimated. The exposure to UV light had no effect on the &beta;-caryophyllene SOA concentration and aerosol mass spectrometer (AMS) measurements. The chemical aging of the β-caryophyllene SOA produced was studied by exposing the fresh SOA to high concentrations (10⁷ molecules cm^&minus;3) of OH for several hours. These additional reactions increased the SOA concentration by 15–40% and O : C by approximately 25%. A limited number of experiments suggested that there was a significant impact of the relative humidity on the chemical aging of the SOA. The evaporation rates of β-caryophyllene SOA were quantified by using a thermodenuder allowing us to estimate the corresponding volatility distributions and effective vaporization enthalpies

Urban Oxidation Flow Reactor Measurements Reveal Significant Secondary Organic Aerosol Contributions from Volatile Emissions of Emerging Importance

Mobile sampling studies have revealed enhanced levels of secondary organic aerosol (SOA) in source-rich urban environments. While these enhancements can be from rapidly reacting vehicular emissions, it was recently hypothesized that nontraditional emissions (volatile chemical products and upstream emissions) are emerging as important sources of urban SOA. We tested this hypothesis by using gas and aerosol mass spectrometry coupled with an oxidation flow reactor (OFR) to characterize pollution levels and SOA potentials in environments influenced by traditional emissions (vehicular, biogenic), and nontraditional emissions (e.g., paint fumes). We used two SOA models to assess contributions of vehicular and biogenic emissions to our observed SOA. The largest gap between observed and modeled SOA potential occurs in the morning-time urban street canyon environment, for which our model can only explain half of our observation. Contributions from VCP emissions (e.g., personal care products) are highest in this environment, suggesting that VCPs are an important missing source of precursors that would close the gap between modeled and observed SOA potential. Targeted OFR oxidation of nontraditional emissions shows that these emissions have SOA potentials that are similar, if not larger, compared to vehicular emissions. Laboratory experiments reveal large differences in SOA potentials of VCPs, implying the need for further characterization of these nontraditional emissions