26,063 research outputs found
Joint preload properties of structural threaded fasteners
Proper installation techniques are described and reliable torque-tension values are presented on joint preload /or clamp load/ properties of structural threaded fasteners
Suspended Load Path Tracking Control Using a Tilt-rotor UAV Based on Zonotopic State Estimation
This work addresses the problem of path tracking control of a suspended load
using a tilt-rotor UAV. The main challenge in controlling this kind of system
arises from the dynamic behavior imposed by the load, which is usually coupled
to the UAV by means of a rope, adding unactuated degrees of freedom to the
whole system. Furthermore, to perform the load transportation it is often
needed the knowledge of the load position to accomplish the task. Since
available sensors are commonly embedded in the mobile platform, information on
the load position may not be directly available. To solve this problem in this
work, initially, the kinematics of the multi-body mechanical system are
formulated from the load's perspective, from which a detailed dynamic model is
derived using the Euler-Lagrange approach, yielding a highly coupled, nonlinear
state-space representation of the system, affine in the inputs, with the load's
position and orientation directly represented by state variables. A zonotopic
state estimator is proposed to solve the problem of estimating the load
position and orientation, which is formulated based on sensors located at the
aircraft, with different sampling times, and unknown-but-bounded measurement
noise. To solve the path tracking problem, a discrete-time mixed
controller with pole-placement constraints
is designed with guaranteed time-response properties and robust to unmodeled
dynamics, parametric uncertainties, and external disturbances. Results from
numerical experiments, performed in a platform based on the Gazebo simulator
and on a Computer Aided Design (CAD) model of the system, are presented to
corroborate the performance of the zonotopic state estimator along with the
designed controller
Imagining a New Nation: Patriotism and National Identity in the Writing of Late-18th Century American Women
Benedict Anderson defined the nation as “an imagined political community” that is “imagined as both inherently limited and sovereign.” The research for this paper began with a desire to know how American women in the time leading up to, during, and immediately after the American Revolution and War of Independence did or did not imagine themselves as members of the newly emerging political community eventually known as the United States of America. As tensions between the Colonies and Great Britain increased, as tea was dumped in Boston harbor, and as independence was declared in 1776, how did women make sense of these events and their significance for their own identities? As many colonists began to reject their previous identity as British subjects and colonial residents in favor of a new civic identity as members of a separate, sovereign nation, they needed to define what it meant to be American. Who was an American citizen? What did it mean to be an American citizen? What was it that bound the disparate thirteen colonies and their diverse populations together into one cohesive nation? Where were the limits to this newly imagined community, and did these limits include or exclude women
Epistemic Harm in Empathy
This paper delves into the intricacies of the concept of epistemic harm. Particularly, epistemic harm is used as a case study to gain insights into the efficacy and distinctiveness of the concept of harm vis-à-vis related constructs such as violence and trauma within the domain of social psychology. The paper underscores the pertinence of the concept of epistemic harm in the context of empathetic testimonial exchange using autism studies as a sample case. Subsequently, empathy is characterised as innately engendering epistemic harm, manifesting both at the inter-subjective and intra-subjective levels. The paper concludes with a contemplation on the significance of the idea of epistemic harm within the broader field of harm research
Identity as a Determinant of the Overreporting of Church Attendance in Canada
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91358/1/j.1468-5906.2012.01640.x.pd
Set-based state estimation and fault diagnosis using constrained zonotopes and applications
This doctoral thesis develops new methods for set-based state estimation and
active fault diagnosis (AFD) of (i) nonlinear discrete-time systems, (ii)
discrete-time nonlinear systems whose trajectories satisfy nonlinear equality
constraints (called invariants), (iii) linear descriptor systems, and (iv)
joint state and parameter estimation of nonlinear descriptor systems. Set-based
estimation aims to compute tight enclosures of the possible system states in
each time step subject to unknown-but-bounded uncertainties. To address this
issue, the present doctoral thesis proposes new methods for efficiently
propagating constrained zonotopes (CZs) through nonlinear mappings. Besides,
this thesis improves the standard prediction-update framework for systems with
invariants using new algorithms for refining CZs based on nonlinear
constraints. In addition, this thesis introduces a new approach for set-based
AFD of a class of nonlinear discrete-time systems. An affine parametrization of
the reachable sets is obtained for the design of an optimal input for set-based
AFD. In addition, this thesis presents new methods based on CZs for set-valued
state estimation and AFD of linear descriptor systems. Linear static
constraints on the state variables can be directly incorporated into CZs.
Moreover, this thesis proposes a new representation for unbounded sets based on
zonotopes, which allows to develop methods for state estimation and AFD also of
unstable linear descriptor systems, without the knowledge of an enclosure of
all the trajectories of the system. This thesis also develops a new method for
set-based joint state and parameter estimation of nonlinear descriptor systems
using CZs in a unified framework. Lastly, this manuscript applies the proposed
set-based state estimation and AFD methods using CZs to unmanned aerial
vehicles, water distribution networks, and a lithium-ion cell.Comment: My PhD Thesis from Federal University of Minas Gerais, Brazil. Most
of the research work has already been published in DOIs
10.1109/CDC.2018.8618678, 10.23919/ECC.2018.8550353,
10.1016/j.automatica.2019.108614, 10.1016/j.ifacol.2020.12.2484,
10.1016/j.ifacol.2021.08.308, 10.1016/j.automatica.2021.109638,
10.1109/TCST.2021.3130534, 10.1016/j.automatica.2022.11042
Private-Public Sector Cooperation in Combating Cybercrime: in Search of a Model
Turnover taxes are generally considered to be risk-free from the tax competition point of view, forthey are levied exclusively at the place of consumption. The Value-Added Tax (VAT) imposed by all EuropeanUnion (EU) member states, though, has become a source of distortion in the trans-Atlantic trade: non-EUsuppliers of electronic services were not required to collect the VAT, while their EU competitors were. The levelplaying field in EU’s foreign trade in electronic services was restored in 2002 by the so-called e-VAT Directivethat obliged non-EU providers of electronic services to charge the VAT at the rate of the member state theirconsumer resides in. This paper argues that besides being largely unenforceable, the Directive has createdanother misbalance in the infra-EU electronic commerce. It is being demonstrated that since the Directive is notapplicable to EU vendors, non-EU businesses can and do circumvent it by establishing daughter companies inEU jurisdictions with the lowest VAT rates and thus spur the infra-EU tax competition
Self Trapping of a Single Bacterium in its Own Chemoattractant
Bacteria (e.g. E. Coli) are very sensitive to certain chemoattractants (e.g.
asparate) which they themselves produce. This leads to chemical instabilities
in a uniform population. We discuss here the different case of a single
bacterium, following the general scheme of Brenner, Levitov and Budrene. We
show that in one and two dimensions (in a capillary or in a thin film) the
bacterium can become self-trapped in its cloud of attractant. This should occur
if a certain coupling constant is larger than unity. We then estimate the
reduced diffusion D_eff of the bacterium in the strong coupling limit, and find
D_eff ~ 1/g.Comment: 4 pages, absolutely no figure
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