Selection from Multivariate Normal Populations

Selection from multivariate normal population

Gaussian Process Model Predictive Control of An Unmanned Quadrotor

The Model Predictive Control (MPC) trajectory tracking problem of an unmanned quadrotor with input and output constraints is addressed. In this article, the dynamic models of the quadrotor are obtained purely from operational data in the form of probabilistic Gaussian Process (GP) models. This is different from conventional models obtained through Newtonian analysis. A hierarchical control scheme is used to handle the trajectory tracking problem with the translational subsystem in the outer loop and the rotational subsystem in the inner loop. Constrained GP based MPC are formulated separately for both subsystems. The resulting MPC problems are typically nonlinear and non-convex. We derived 15 a GP based local dynamical model that allows these optimization problems to be relaxed to convex ones which can be efficiently solved with a simple active-set algorithm. The performance of the proposed approach is compared with an existing unconstrained Nonlinear Model Predictive Control (NMPC). Simulation results show that the two approaches exhibit similar trajectory tracking performance. However, our approach has the advantage of incorporating constraints on the control inputs. In addition, our approach only requires 20% of the computational time for NMPC.Comment: arXiv admin note: text overlap with arXiv:1612.0121

On entropy, specific heat, susceptibility and Rushbrooke inequality in percolation

We investigate percolation, a probabilistic model for continuous phase transition (CPT), on square and weighted planar stochastic lattices. In its thermal counterpart, entropy is minimally low where order parameter (OP) is maximally high and vice versa. Besides, specific heat, OP and susceptibility exhibit power-law when approaching the critical point and the corresponding critical exponents $\alpha, \beta, \gamma$ respectably obey the Rushbrooke inequality (RI) $\alpha+2\beta+\gamma\geq 2$. Their analogues in percolation, however, remain elusive. We define entropy, specific heat and redefine susceptibility for percolation and show that they behave exactly in the same way as their thermal counterpart. We also show that RI holds for both the lattices albeit they belong to different universality classes.Comment: 5 pages, 3 captioned figures, to appear as a Rapid Communication in Physical Review E, 201

Comparative performance analysis of Vacuum Insulation Panels in thermal window shutters

Windows are a major area of heat loss in buildings and can lose up to 10 times more energy than other building elements. In a typical house, around 10% of heat is lost through the windows. Thermal shutters could considerably reduce heat losses through windows and improve the energy performance of buildings. Insulation plays a major role in overall performance of thermal shutters. Advance insulation material such as Vacuum Insulation Panel (VIP) can help in improving the performance of thermal window shutters. VIP with a thermal conductivity of 0.005-0.008 W/mK is a high thermal resistance and energy efficient alternative to conventional thermal insulation materials. In this paper, effect of VIP and conventional insulation has been investigated and compared for enhancing the thermal performance of window shutters using computer simulations. Results indicate significant reduction in heat loss through windows when VIP insulation was employed in internal thermal window shutters. Thermal bridging was found to be the significant factor that deteriorated the performance of the shutter. Reducing heat loss through the frame and surrounding walls could improve the VIP insulated shutter thermal performance by approximately nine times