8,400 research outputs found
Proportional-Integral-Plus Control Strategy of an Intelligent Excavator
This article considers the application of Proportional-Integral-Plus (PIP) control to the Lancaster University Computerised Intelligent Excavator (LUCIE), which is being developed to dig foundation trenches on a building site. Previous work using LUCIE was based on the ubiquitous PI/PID control algorithm, tuned on-line, and implemented in a rather ad hoc manner. By contrast, the present research utilizes new hardware and advanced model-based control system design methods to improve the joint control and so provide smoother, more accurate movement of the excavator arm. In this article, a novel nonlinear simulation model of the system is developed for MATLAB/SIMULINK, allowing for straightforward refinement of the control algorithm and initial evaluation. The PIP controller is compared with a conventionally tuned PID algorithm, with the final designs implemented on-line for the control of dipper angle. The simulated responses and preliminary implementation results demonstrate the feasibility of the approach
Regulatory Focus and Interdependent Economic Decision-Making
Traditional theories of self-interest cannot predict when individuals pursue relative and absolute economic outcomes in interdependent decision-making, but we argue that regulatory focus (Higgins, 1997) can. We propose that a concern with security (prevention focus) motivates concerns with social status, leading to the regulation of relative economic outcomes, but a concern with growth (promotion focus) motivates the maximization of opportunities, leading to a focus on absolute outcomes. Two studies supported our predictions; regardless of prosocial or proself motivations, a promotion focus yielded greater concern with absolute outcomes, but a prevention focus yielded greater concern with relative outcomes. Also, Study 3 revealed that a prevention focus led to a greater rejection of a negative relative but positive absolute outcome in an ultimatum game because of concerns with status. This research reveals that apparently opposing orientations to interdependence – equality and relative gain – serve the same self-regulatory purpose: the establishment of security
Fractality of profit landscapes and validation of time series models for stock prices
We apply a simple trading strategy for various time series of real and
artificial stock prices to understand the origin of fractality observed in the
resulting profit landscapes. The strategy contains only two parameters and
, and the sell (buy) decision is made when the log return is larger
(smaller) than (). We discretize the unit square into the square grid and the profit is
calculated at the center of each cell. We confirm the previous finding that
local maxima in profit landscapes are scattered in a fractal-like fashion: The
number M of local maxima follows the power-law form , but the
scaling exponent is found to differ for different time series. From
comparisons of real and artificial stock prices, we find that the fat-tailed
return distribution is closely related to the exponent observed
for real stock markets. We suggest that the fractality of profit landscape
characterized by can be a useful measure to validate time
series model for stock prices.Comment: 10pages, 6figure
Comment on "Phase transition in a one-dimensional Ising ferromagnet at zero temperature using Glauber dynamics with a synchronous updating mode"
Sznajd-Weron in [Phys. Rev. E {\bf 82}, 031120 (2010)] suggested that the
one-dimensional Ising model subject to the zero temperature synchronous Glauber
dynamics exhibits a discontinuous phase transition. We show here instead that
the phase transition is of a continuous nature and identify critical exponents:
, , and , via a systematic
finite-size scaling analysis.Comment: 2 pages 2 figure
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