Time Dynamic Model Research Articles

Real-time Pegasus propulsion system model V/STOL-piloted simulation evaluation

A real time propulsion system modeling technique suitable for use in man-in-the-loop simulator studies was developd. This technique provides the system accuracy, stability, and transient response required for integrated aircraft and propulsion control system studies. A Pegasus-Harrier propulsion system was selected as a baseline for developing mathematical modeling and simulation techniques for VSTOL. Initially, static and dynamic propulsion system characteristics were modeled in detail to form a nonlinear aerothermodynamic digital computer simulation of a Pegasus engine. From this high fidelity simulation, a real time propulsion model was formulated by applying a piece-wise linear state variable methodology. A hydromechanical and water injection control system was also simulated. The real time dynamic model includes the detail and flexibility required for the evaluation of critical control parameters and propulsion component limits over a limited flight envelope. The model was programmed for interfacing with a Harrier aircraft simulation. Typical propulsion system simulation results are presented.

Gaussian Estimation of Structural Parameters in Higher Order Continuous Time Dynamic Models

This paper is concerned with the efficient estimation of structural parameters in closed linear systems of higher order stochastic differential equations when the data are in discrete form and the model generally includes both stock and flow variables. A general existence and uniqueness theorem for the solution of such a system is proved and used in the rigorous derivation of exact discrete models satisfied by the various types of data. It is shown how these models can be used in the computation of various asymptotically efficient estimates obtained by the maximization of the Gaussian likelihood or approximations to it.

Qualitative Analysis and Econometric Estimation of Continuous Time Dynamic Models.

Journal Article Qualitative Analysis and Econometric Estimation of Continuous Time Dynamic Models Get access Qualitative Analysis and Econometric Estimation of Continuous Time Dynamic Models. By Giancarlo Gandolfo. (Amsterdam: North-Holland, 1981. Pp. xiv + 253. $39.00, Dfl 80.00.) Kumaraswamy Velupillai Kumaraswamy Velupillai European University Institute, Florence Search for other works by this author on: Oxford Academic Google Scholar The Economic Journal, Volume 92, Issue 368, 1 December 1982, Pages 981–983, https://doi.org/10.2307/2232687 Published: 01 December 1982

Beggar-my-neighbour devaluation: The case of Ireland, 1967

The purpose of this empirical study is to assess the effectiveness of a beggar-my-neighbour devaluation using the Irish devaluation against sterling in 1967 as a case study. A dynamic continuous time model of a small, open economy with a money, goods and labour market is estimated. The simulation results show that while the effects of devaluation were in the direction predicted, raising the stock of foreign reserves, the rate of inflation and lowering unemployment, the magnitude of the effects, especially on external balance was small.

Time scales and dynamic models of deep-sea sedimentation

Models of very long term geochemical cycling of material include oceanic sediments as a part of the much larger system of mantle differentiation, production of sea floor, subduction, and continental growth. Mass balance considerations show that the system cannot be in steady state if pelagic sediment has always had its present composition. An approximate steady state system is possible if pelagic sediments were exclusively red clay and siliceous ooze. The origin of the calcareous plankton 100 m.y. ago apparently initiated a process interior to the system which is driving the system toward a new steady state. On a time scale of tens of millions of years, sea level fluctuations associated with changes in the length of oceanic ridges and the rate of spreading cause differential partitioning of sediments between shelf areas and the oceanic realm. This process may alter the inputs to the ocean system and affect both the volume and the composition of oceanic sediment. For shorter time scales the sedimentary record reflects variations in internal processes of the ocean system.

The Specification of Adaptive Expectations in Continuous Time Dynamic Economic Models

The Specification of Adaptive Expectations in Continuous Time Dynamic Economic Models

Optimal Production, Investment, Advertising, and Price Controls for the Dynamic Monopoly Firm

In this paper, a dynamic continuous time model, encompassing operations, investments, output prices, informative advertising, and brand advertising, is formulated as an optimal control problem in an activity analysis context. In the model, the objective of the firm is to maximise, subject to various constraints, the discounted value of accumulated savings over the finite decision-making interval plus the discounted value of capacity at the end of the interval. The state variables are capacity, goodwill of type 1 reflecting informative advertising, goodwill of type 2 reflecting brand advertising, net debt, and the output price. The controls are the scale of operation, the purchase of new capacity, informative advertising, brand advertising, and the rate of change of the output price. Final capacity, goodwill of types 1 and 2, net debt, and price are control parameters. There are several inequality constraints. Using results in control theory, the optimal controls are completely characterized. These results are interpreted using the properties of the Value Equation. In addition, the control problem is transformed into an approximate programming problem.

Optimal Operations & Investments of the Firm

In this paper, a dynamic continuous time model of the firm, encompassing operations and investments, is formulated as an optimal control problem in an activity analysis context. In the model, the objective of the firm is to maximize, subject to various constraints, the discounted value of operating profits less the costs of new capacity and the interest on borrowed funds (or plus the interest on savings) over a fixed decision-making interval plus the discounted value of capacity at the end of the period. The state variables are capacity and debt, and the controls are scale of operation and rate of purchase of new capacity; the final capacity and debt are control parameters. There are several inequality constraints. Using results in control theory, the optimal controls are determined for the case the rate of production is linear in the scale variable, the growth of capacity is linear in the rate of purchase of new capacity and the attrition of capacity is linear in the amount of capacity. Extensions of the model are made to include multiple processes.