3,208 research outputs found
Multi-Objective Flight Control for Ride Quality Improvement for Flexible Aircraft
This paper describes a multi-objective flight control system design for ride quality improvement for flexible aircraft using multi-functional distributed flight control surfaces. A multi-objective optimal control design is developed to provide an acceleration suppression capability in conjunction with a gust load alleviation in order to provide ride quality improvement. A gust estimation is developed to estimate the gust load using a recursive least-squares algorithm. A ride quality assessment study is conducted using a flexible wing generic transport model. Six different flight control designs are implemented. The study shows that ride quality can be significantly improved with the acceleration suppression control
Development of an Aeroservoelastic Model for Gust Load Alleviation of the NASA Common Research Model Wind Tunnel Experiment
As aircraft move to using composite materials as their primary structure they become lighter and more flexible as well. This presents some significant challenges in association with gust load alleviation. In this paper we develop an aeroservoelastic model for use in developing controllers that utilize distributed control surfaces for active gust load alleviation in a set of wind tunnel experiments. The model is based on an preexisting aeroelastic wing tunnel model and compares the baseline functionality to it. We also provide simple full state feedback simulations for the model
Efficient Lock-free Binary Search Trees
In this paper we present a novel algorithm for concurrent lock-free internal
binary search trees (BST) and implement a Set abstract data type (ADT) based on
that. We show that in the presented lock-free BST algorithm the amortized step
complexity of each set operation - {\sc Add}, {\sc Remove} and {\sc Contains} -
is , where, is the height of BST with number of nodes
and is the contention during the execution. Our algorithm adapts to
contention measures according to read-write load. If the situation is
read-heavy, the operations avoid helping pending concurrent {\sc Remove}
operations during traversal, and, adapt to interval contention. However, for
write-heavy situations we let an operation help pending {\sc Remove}, even
though it is not obstructed, and so adapt to tighter point contention. It uses
single-word compare-and-swap (\texttt{CAS}) operations. We show that our
algorithm has improved disjoint-access-parallelism compared to similar existing
algorithms. We prove that the presented algorithm is linearizable. To the best
of our knowledge this is the first algorithm for any concurrent tree data
structure in which the modify operations are performed with an additive term of
contention measure.Comment: 15 pages, 3 figures, submitted to POD
A geometric proof of the existence of definable Whitney stratifications
We give a geometric proof of existence of Whitney stratifications of
definable sets in o-minimal structures.Comment: 9 pages, 1 figur
ECONOMIC Potential of Renewable Energy in Vietnam's Power Sector
A bottom-up Integrated Resource Planning model is used to examine the economic potential of renewable energy in Vietnam’s power sector. In a baseline scenario without renewables, coal provides 44% of electricity generated from 2010 to 2030. The use of renewables could reduce that figure to 39%, as well as decrease the sector’s cumulative emission of CO2 by 8%, SO2 by 3%, and NOx by 4%. In addition,renewables could avoid installing 4.4GW in fossil fuel generating capacity, conserve domestic coal,decrease coal and gases imports, improving energy independence and security. Wind could become cost-competitive assuming high but plausible on fossil fuel prices, if the cost of the technology falls to 900 US$/kW
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