On-demand Aerodynamics in Integrally Actuated Membranes with Feedback Control

This paper is a numerical investigation on model reduction and control system design of integrally actuated membrane wings. A high-fidelity electro-aeromechanical model is used for the simulation of the dynamic fluid-structure interaction between a low-Reynolds-number flow and a dielectric elastomeric wing. Two reduced-order models with different levels of complexity are then derived. They are based on the projection of the fullorder discretisation of fluid and structure on modal shapes obtained from eigenvalue analysis and Proper Orthogonal Decomposition. The low-order systems are then used for the design of Proportional-Integral-Derivative and Linear Quadratic Gaussian feedback schemes to control wing lift. When implemented in the full-order model, closed-loop dynamics are in very good agreement with the reduced-order model for both tracking and gust rejection, demonstrating the suitability of the approach. The control laws selected in this work were found to be effective only for low-frequency disturbances due to the large phase delay introduced by the fluid convective time-scales, but results demonstrate the potential for the aerodynamic control of membrane wings in outdoor flight using dielectric elastomers

The macroeconomics of price reform in socialist countries : a dynamic framework

This paper emphasizes the fiscal underpinnings of the inflationary process and those particular dynamics when a dual price system is present. In particular, it explores the links between price controls and decontrols and the government budget, mainly through the flow of subsidies to either consumers or producers. A clear conclusion is that without consistency in macroeconomic policy, price liberalization may simply exacerbate imbalances and ultimately provide a mechanism for sustaining inflation, hencecompromising a basic objective of macroeconomic policy.Access to Markets,Economic Theory&Research,Environmental Economics&Policies,Insurance&Risk Mitigation,Markets and Market Access

The Flexible Exchange Rate System: Experience and Alternatives

We review ten aspects of how floating exchange rates have worked in practice, contrasted with ten characteristics that the system was supposed to have in theory. We conclude that the foreign exchange market is characterized by high transactions-volume, short-term horizons, and an absence of stabilizing speculation. As a result, the exchange rate at times strays from the equilibrium level dictated by fundamentals, contrary to theory. We then look at ten proposed alternatives to the current system. Four entail decentralized policy rules: new classical macroeconomics, a gold standard, monetarism, and nominal income targeting. Four foresee enhanced international coordination: G-7 "objective indicators," Williamson target zones, McKinnon "world monetarism," and a "Hosomi Fund." Two propose enhanced independence: a "Tobin tax" on transactions, and a dual exchange rate. We conclude that one might build a case for intervention from the observed failure of international financial markets to behave as in the theoretical ideal, but that government intervention in practice is just as likely to fall short of the theoretical ideal

Application of Unified Power Flow Controller to Improve the Performance of Wind Energy Conversion System

This research introduces the unified power flow controller (UPFC) as a means to improve the overall performance of wind energy conversion system (WECS) through the development of an appropriate control algorithm. Also, application of the proposed UPFC control algorithm has been extended in this research to overcome some problems associated with the internal faults associated with WECS- voltage source converter (VSC), such as miss-fire, fire-through and dc-link faults

An improved equivalent force control algorithm for hybrid seismic testing of nonlinear systems

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Exchange rate dynamics and monetary policy - Evidence from a non-linear DSGE-VAR approach

In this paper, we reconsider the question how monetary policy influences exchange rate dynamics. To this end, a vector autoregressive (VAR) model is combined with a two-country dynamic stochastic general equilibrium (DSGE) model. Instead of focusing exclusively on how monetary policy shocks affect the level of exchange rates, we also analyze how they impact exchange rate volatility. Since exchange rate volatility is not observed, we estimate it alongside the remaining quantities in the model. Our findings can be summarized as follows. Contractionary monetary policy shocks lead to an appreciation of the home currency, with exchange rate responses in the short-run typically undershooting their long-run level of appreciation. They also lead to an increase in exchange rate volatility. Historical and forecast error variance decompositions indicate that monetary policy shocks explain an appreciable amount of exchange rate movements and the corresponding volatility.Series: Department of Economics Working Paper Serie

Adaptive and Robust Cross-Voltage-Level Power Flow Control of Active Distribution Networks

The large-scale integration of Distributed Energy Resources (DERs) into the electric power system offers new opportunities to ensure stability. For example, Active Distribution Networks (ADNs) can be used in (sub-)transmission systems in the emergency state, as far as high robustness and performance of the ADN control are guaranteed. This paper presents an adaptive control system for ADN's cross-voltage-level power flow control. For this purpose, the gain scheduling approach is used. Furthermore, this work introduces a method for control parameter tuning. In order to validate the control parameter tuning, the adaptive control system is analyzed regarding robustness and performance using an exemplary medium voltage grid. In addition, the influence of uncertainties is examined. Finally, the operation of the adaptive control system is demonstrated by performing time-domain simulations.Comment: In proceedings of the 11th Bulk Power Systems Dynamics and Control Symposium (IREP 2022), July 25-30, 2022, Banff, Canad

Fuzzy logic for thermal process

The main purpose of this project is to compare the performance of current proportional-integral-derivative (PID) method that widely used in industry with the Fuzzy Logic Control as an alternative