A common type of integral to solve numerically in computational room acoustics and other applications is the diffraction integral. Various formulations are encountered but they are usually of the Fourier-type, which means an oscillating integrand which becomes increasingly expensive to compute for increasing frequencies. Classical asympotic solution methods, such as the stationary-phase method,...

this paper proposes a new smart antenna beamforming scheme based on electronically steerable parasitic array radiator (espar). the proposed method is capable of providing better capacity compared to the conventional espar. the termination of each antenna element in this structure comprises a pin diode in addition to a varactor. using pin diode besides the varactor provides more degrees of freed...

Steepest descent is central in variational mathematics. We present a new transparent existence proof for curves of near-maximal slope — an influential notion of steepest descent in a nonsmooth setting. We moreover show that for semi-algebraic functions — prototypical nonpathological functions in nonsmooth optimization — such curves are precisely the solutions of subgradient dynamical systems.

An efficient method to evaluate the surface fields excited on an electrically large dielectric-coated circular cylinder is presented. The efficiency of the method results from the circumferentially propagating representation of the Green’s function as well as its efficient numerical evaluation along a steepest descent path. The circumferentially propagating series representation of the appropri...

The block preconditioned steepest descent iteration is an iterative eigensolver for subspace eigenvalue and eigenvector computations. An important area of application of the method is the approximate solution of mesh eigenproblems for self-adjoint and elliptic partial differential operators. The subspace iteration allows to compute some of the smallest eigenvalues together with the associated i...

By extending the classical analysis techniques due to Samokish, Faddeev and Faddeeva, and Longsine and McCormick among others, we prove the convergence of preconditioned steepest descent with implicit deflation (PSD-id) method for solving Hermitian-definite generalized eigenvalue problems. Furthermore, we derive a nonasymptotic estimate of the rate of convergence of the PSD-id method. We show t...

A special class of four-point correlation functions in the maximally supersymmetric Yang-Mills theory is given by square Fredholm determinant a generalized Bessel kernel. In this note, we re-express its logarithmic derivatives terms two-dimensional Riemann-Hilbert problem. We solve latter null limit making use Deift-Zhou steepest descent. reproduce exact octagonal anomalous dimension 't Hooft c...