10,194 research outputs found
Design criteria for flight evaluation. Monograph 4 - Control system evaluation
Methods and analyses for flight evaluation of control systems for multistage launch vehicle
Longitudinal control effectiveness and entry dynamics of a single-stage-to-orbit vehicle
The classical theory of flight dynamics for airplane longitudinal stability and control analysis was extended to the case of a hypervelocity reentry vehicle. This includes the elements inherent in supersonic and hypersonic flight such as the influence of the Mach number on aerodynamic characteristics, and the effect of the reaction control system and aerodynamic controls on the trim condition through a wide range of speed. Phugoid motion and angle of attack oscillation for typical cases of cruising flight, ballistic entry, and glide entry are investigated. In each case, closed form solutions for the variations in altitude, flight path angle, speed and angle of attack are obtained. The solutions explicitly display the influence of different regions design parameters and trajectory variables on the stability of the motion
Qualitative analysis of dynamic equations on time scales
In this article, we establish the Picard-Lindelof theorem and approximating
results for dynamic equations on time scale. We present a simple proof for the
existence and uniqueness of the solution. The proof is produced by using
convergence and Weierstrass M-test. Furthermore, we show that the Lispchitz
condition is not necessary for uniqueness. The existence of epsilon-approximate
solution is established under suitable assumptions. Moreover, we study the
approximate solution of the dynamic equation with delay by studying the
solution of the corresponding dynamic equation with piecewise constant
argument. We show that the exponential stability is preserved in such
approximations.Comment: 13 page
Optimal Battery Energy Storage Placement for Transient Voltage Stability Enhancement
A placement problem for multiple Battery Energy Storage System (BESS) units
is formulated towards power system transient voltage stability enhancement in
this paper. The problem is solved by the Cross-Entropy (CE) optimization
method. A simulation-based approach is adopted to incorporate higher-order
dynamics and nonlinearities of generators and loads. The objective is to
maximize the voltage stability index, which is set up based on certain
grid-codes. Formulations of the optimization problem are then discussed.
Finally, the proposed approach is implemented in MATLAB/DIgSILENT and tested on
the New England 39-Bus system. Results indicate that installing BESS units at
the optimized location can alleviate transient voltage instability issue
compared with the original system with no BESS. The CE placement algorithm is
also compared with the classic PSO (Particle Swarm Optimization) method, and
its superiority is demonstrated in terms of fewer iterations for convergence
with better solution qualities.Comment: This paper has been accepted by the 2019 IEEE PES General Meeting at
Atlanta, GA in August 201
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