7 research outputs found
Stability of FFLS-based diffusion adaptive filter under a cooperative excitation condition
In this paper, we consider the distributed filtering problem over sensor
networks such that all sensors cooperatively track unknown time-varying
parameters by using local information. A distributed forgetting factor least
squares (FFLS) algorithm is proposed by minimizing a local cost function
formulated as a linear combination of accumulative estimation error. Stability
analysis of the algorithm is provided under a cooperative excitation condition
which contains spatial union information to reflect the cooperative effect of
all sensors. Furthermore, we generalize theoretical results to the case of
Markovian switching directed graphs. The main difficulties of theoretical
analysis lie in how to analyze properties of the product of non-independent and
non-stationary random matrices. Some techniques such as stability theory,
algebraic graph theory and Markov chain theory are employed to deal with the
above issue. Our theoretical results are obtained without relying on the
independency or stationarity assumptions of regression vectors which are
commonly used in existing literature.Comment: 12 page
Investigation of solution techniques for large sparse band width matrix equations of linear systems
Includes bibliographical references (leaves 107-108
Some remarks on load modeling in nonlinear structural analysis–Statics with large deformations–Consistent treatment of follower load effects and load control
Load modeling in nonlinear statics, particularly incorporating large deformations differs significantly from the treatment in linear analysis. As in structural dynamics masses in a gravity field generate the loading, their location, and their modifications within the deformation process must be considered in a nonlinear simulation. A specific view besides loading by masses is on gas and fluid interaction with structures. In addition, load control using specifically designed algorithms is evaluated with respect to realistic applications. Within the load modeling an unavoidable, however side aspect, is the general discussion about the so-called follower forces and non-conservative loading. As an example of real-world applications, the specifics of inflated rubber dams are presented
Design and Analysis of Air-Stiffened Vacuum Lighter-Than-Air Structures
Lighter-than-air (LTA) systems have been developed for numerous applications and have taken several forms. Airships, aerostats, blimps, and balloons are all part of this family of systems, which uses Archimedes principle to achieve neutral and positive buoyancy in air by replacing an air volume with LTA gases. These lifting gases stiffen the otherwise compliant envelope structures, allowing them to sustain the pressure difference brought by the displaced air. The compliance of these structures is a byproduct of the weight requirement, materials and geometrical arrangement of which these structures are built from, typically resulting in dimensionalities that exhibit low or virtually non-existent in-plane bending stiffness. The former has constrained the development of LTA structures that utilize an internal partial vacuum, rather than a lifting gas, to achieve positive buoyancy, where the structure would be subjected to a pressure differential near atmospheric pressure. Given the above limitation, this research presents the development trajectory and structural characterization of air stiffened designs, which utilize air to shape and serve as the core of a set of enclosing envelopes. The development trajectory established a simulation framework that enables the structural characterization of air-stiffened designs under a variety of geometric and loading conditions. Such framework allowed for the development of finite element solutions that included geometric, fluid-structure and contact nonlinearities, with capacity for further generalization. Given the developed framework, the structural characterization of the Helical Sphere and Icoron air-stiffened designs demonstrated a reduction of material modulus and strength requirements compared to membrane-over-frame designs, and showed the capability of air-stiffened designs to be tailored for specific material strength limits
Theorems of structural and geometric variation for linear and nonlinear finite element analysis
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