72,428 research outputs found
Robotic manipulation of a rotating chain
This paper considers the problem of manipulating a uniformly rotating chain:
the chain is rotated at a constant angular speed around a fixed axis using a
robotic manipulator. Manipulation is quasi-static in the sense that transitions
are slow enough for the chain to be always in "rotational" equilibrium. The
curve traced by the chain in a rotating plane -- its shape function -- can be
determined by a simple force analysis, yet it possesses complex multi-solutions
behavior typical of non-linear systems. We prove that the configuration space
of the uniformly rotating chain is homeomorphic to a two-dimensional surface
embedded in . Using that representation, we devise a manipulation
strategy for transiting between different rotation modes in a stable and
controlled manner. We demonstrate the strategy on a physical robotic arm
manipulating a rotating chain. Finally, we discuss how the ideas developed here
might find fruitful applications in the study of other flexible objects, such
as elastic rods or concentric tubes.Comment: 12 pages, 9 figure
Design of Ad Hoc Wireless Mesh Networks Formed by Unmanned Aerial Vehicles with Advanced Mechanical Automation
Ad hoc wireless mesh networks formed by unmanned aerial vehicles (UAVs)
equipped with wireless transceivers (access points (APs)) are increasingly
being touted as being able to provide a flexible "on-the-fly" communications
infrastructure that can collect and transmit sensor data from sensors in
remote, wilderness, or disaster-hit areas. Recent advances in the mechanical
automation of UAVs have resulted in separable APs and replaceable batteries
that can be carried by UAVs and placed at arbitrary locations in the field.
These advanced mechanized UAV mesh networks pose interesting questions in terms
of the design of the network architecture and the optimal UAV scheduling
algorithms. This paper studies a range of network architectures that depend on
the mechanized automation (AP separation and battery replacement) capabilities
of UAVs and proposes heuristic UAV scheduling algorithms for each network
architecture, which are benchmarked against optimal designs.Comment: 12 page
Shape manipulation using physically based wire deformations
This paper develops an efficient, physically based shape manipulation technique. It defines a 3D model with profile curves, and uses spine curves generated from the profile curves to control the motion and global shape of 3D models. Profile and spine curves are changed into profile and spine wires by specifying proper material and geometric properties together with external forces. The underlying physics is introduced to deform profile and spine wires through the closed form solution to ordinary differential equations for axial and bending deformations. With the proposed approach, global shape changes are achieved through manipulating spine wires, and local surface details are created by deforming profile wires. A number of examples are presented to demonstrate the applications of our proposed approach in shape manipulation
An hierarchical approach to hull form design
As ship design tools become more integrated and more advanced analysis tools are introduced, the ability to rapidly develop and modify hull forms becomes essential. Modern hull design applications give an experienced user the ability to create almost any shape of hull. However, the direct manipulation of hull surface representations is laborious and may limit the exploration of design concept to the fullest extent. Transformation of parent forms and parametric hull generation tools can provide a quick solution, but neither method is conducive for innovative design. A hull design tool is required that can integrate the separate techniques creating a fair hull form surface that can be modified easily throughout the design process. This paper explores the concept of separating the hull surface into global and local features by establishing a hierarchical definition structure and introduces some of the benefits of this approach
An Empirical Study of the Manipulability of Single Transferable Voting
Voting is a simple mechanism to combine together the preferences of multiple
agents. Agents may try to manipulate the result of voting by mis-reporting
their preferences. One barrier that might exist to such manipulation is
computational complexity. In particular, it has been shown that it is NP-hard
to compute how to manipulate a number of different voting rules. However,
NP-hardness only bounds the worst-case complexity. Recent theoretical results
suggest that manipulation may often be easy in practice. In this paper, we
study empirically the manipulability of single transferable voting (STV) to
determine if computational complexity is really a barrier to manipulation. STV
was one of the first voting rules shown to be NP-hard. It also appears one of
the harder voting rules to manipulate. We sample a number of distributions of
votes including uniform and real world elections. In almost every election in
our experiments, it was easy to compute how a single agent could manipulate the
election or to prove that manipulation by a single agent was impossible.Comment: To appear in Proceedings of the 19th European Conference on
Artificial Intelligence (ECAI 2010
Tension Dynamics and Linear Viscoelastic Behavior of a Single Semiflexible Polymer Chain
We study the dynamical response of a single semiflexible polymer chain based
on the theory developed by Hallatschek et al. for the wormlike-chain model. The
linear viscoelastic response under oscillatory forces acting at the two chain
ends is derived analytically as a function of the oscillation frequency . We
shall show that the real part of the complex compliance in the low frequency
limit is consistent with the static result of Marko and Siggia whereas the
imaginary part exhibits the power-law dependence +1/2. On the other hand, these
compliances decrease as the power law -7/8 for the high frequency limit. These
are different from those of the Rouse dynamics. A scaling argument is developed
to understand these novel results.Comment: 23 pages, 6 figure
Credit risk management in banks: Hard information, soft Information and manipulation
The role of informationās processing in bank intermediation is a crucial input. The bank has access to different types of information in order to manage risk through capital allocation for Value at Risk coverage. Hard information, contained in balance sheet data and produced with credit scoring, is quantitative and verifiable. Soft information, produced within a bank relationship, is qualitative and non verifiable, therefore manipulable, but produces more precise estimation of the debtorās quality. In this article, we investigate the impact of the informationās type on credit risk management in a principalagent framework with moral hazard with hidden information. The results show that access to soft information allows the banker to decrease the capital allocation for VaR coverage. We also show the existence of an incentive of the credit officer to manipulate the signal based on soft information that he produces. Therefore, we propose to implement an adequate incentive salary package which unables this manipulation. The comparison of the results from the two frameworks (information hard versus combination of hard and soft information) using simulations confirms that soft information gives an advantage to the banker but requires particular organizational modifications within the bank, as it allows to reduce capital allocation for VaR coverage.Hard information; Soft information; risk management; Value at Risk; moral hazard; hidden information; manipulation
Strategic trading and manipulation with spot market power
When a spot market monopolist has a position in a corresponding futures market, he has an incentive to deviate from the spot market optimum to make this position more profitable. Rational futures market makers take this into account when setting prices. We show that the monopolist, by randomizing his futures market position, can strategically exploit his market power at the expense of other futures market participants. Furthermore, traders without market power can manipulate futures prices by hiding their orders behind the monopolist's strategic trades. The moral hazard problem stemming from spot market power thus provides a venue for strategic trading and manipulation that parallels the adverse selection problem stemming from inside information. Klassifikation: D82, G1
- ā¦