Concept of spinsonde for multi-cycle measurement of vertical wind profile of tropical cyclones

Tropical cyclones and cyclogenesis are active areas of research. Chute-operated dropsondes jointly developed by NASA and NCAR are capable of acquiring high resolution vertical wind profile of tropical cyclones. This paper proposes a chute-free vertical retardation technique (termed as spinsonde) that can accurately measure vertical wind profile. Unlike the expendable dropsondes, the spinsonde allows multi-cycle measurement to be performed within a single flight. Proof of principle is demonstrated using a simulation software and results indicate that the GPS ground speed correlates with the wind speeds to within +/-5 km/h. This technique reduces flying weight and increases payload capacity by eliminating bulky chutes. Maximum cruising speed (Vh) achieved by the spinsonde UAV is 372 km/h.Comment: arXiv admin note: substantial text overlap with arXiv:1407.845

An Efficient Approach for Computing Optimal Low-Rank Regularized Inverse Matrices

Standard regularization methods that are used to compute solutions to ill-posed inverse problems require knowledge of the forward model. In many real-life applications, the forward model is not known, but training data is readily available. In this paper, we develop a new framework that uses training data, as a substitute for knowledge of the forward model, to compute an optimal low-rank regularized inverse matrix directly, allowing for very fast computation of a regularized solution. We consider a statistical framework based on Bayes and empirical Bayes risk minimization to analyze theoretical properties of the problem. We propose an efficient rank update approach for computing an optimal low-rank regularized inverse matrix for various error measures. Numerical experiments demonstrate the benefits and potential applications of our approach to problems in signal and image processing.Comment: 24 pages, 11 figure

Is Harry Frankfurt’s ‘Doctrine of Sufficiency’ Sufficient?

In his article, “Equality as a Moral Ideal”, Harry Frankfurt argues against economic egalitarianism and presents what he calls the “doctrine of sufficiency.” According to the doctrine of sufficiency, what is morally important is not relative economic equality, but rather, whether somebody has enough, where “having enough” is a non-comparative standard of reasonable contentment that may differ from person to person given his/her aims and circumstances. The purpose of this paper is to show that Frankfurt’s original arguments in support for his doctrine of sufficiency have critical problems that Frankfurt himself does not properly recognize. In the end, I will argue that in order to solve these problems the doctrine of sufficiency cannot help but to incorporate certain prioritarian commitments – commitments which many would view as implying economic egalitarianism. This is embarrassing for a doctrine whose raison d’être was mainly to defeat economic egalitarianism

Competing Orders and Superconductivity in the Doped Mott Insulator on the Shastry-Sutherland Lattice

Quantum antiferromagnets on geometrically frustrated lattices often allow a number of unusual paramagnetic ground states. The fate of these Mott insulators upon doping is an important issue that may shed some light on the high $T_c$ cuprate problem. We consider the doped Mott insulator on the Shastry-Sutherland lattice via the t-J model. The U(1) slave-boson mean field theory reveals the strong competition between different broken symmetry states. It is found that, in some ranges of doping, there exist superconducting phases with or without coexisting translational-symmetry- breaking orders such as the staggered flux or dimerization. Our results will be directly relevant to SrCu$_2$(BO$_3$)$_2$ when this material is doped in future.Comment: 4 pages, 3 figure