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Browsing MATH Research Publications by Issue Date

Browsing MATH Research Publications by Issue Date

Now showing items 1-20 of 42

Pole placement by linear quadratic modification for continuous time systems

Rousan, N. S.; Sawan, M. Edwin (IEEE, 1991-06-26)

This paper bridges the gap between linear quadratic solution and pole placement providing a simple criterion sucht that the resulting optimal gain places the closed loop eigenvalues at desired locations. The method has the ...
Constrained pole placement by linear quadratic modification

Rousan, N. S.; Sawan, M. Edwin (IEEE, 1991-06-26)

A noniterative method is introduced that will enable the designer to find an optmal one step state feedback controller. The controller will place the eigenvalues of the closed loop system in a specified disk.
The stabilization of a linearized self-excited wave equation by an energy absorbing boundary

Sarhangi, G.R.; Najafi, M.; Wang, H. (IEEE, 1992-06-24)

We study the linrized self-excited wave quation tt - A £ -P(s) tg=0, where P(s)>0, P(r)eL(f), in a bounded domain 0cRI with smooth bounar r whee boun y dampig is prst. coniering the prtii Fr 1r.).of he bouM~ ron which ...
Numerical comparison of negative damping bounds in a specified domain when the wave speed varies

Najafi, M.; Sarhangi, G.R.; Sawan, M. Edwin (IEEE, 1992-06-24)

The energy decay of a self-excited wave equation utt - c2 Â¿ u - P(x)ut = 0 is studied where the wave speed c is greater than one, P(x) Â¿ 0, and P(x) LÂ¿(Â¿), Â¿ Â¿ Â¿ Rn. Moreover, the relationship between two bounds for ...
Stability of coupled strings vibration system due to different boundary conditions

Sarhangi, G.R.; Najafi, M.; Wang, H. (IEEE, 1993-06-02)

We study the rate of convergence of a coupled wave systems under two different boundary conditions, energy absorbing in two ends for one and free or fixed boundary controls in two ends for the other one. We will observe ...
On the existence of convex classical solutions to a generalized Prandtl-Batchelor free boundary problem

Acker, Andrew (Birkhäuser Verlag, Basel, 2004)

Under reasonably general assumptions, we prove the existence of convex classical solutions for the Prandtl-Batchelor free boundary problem in fluid dynamics, in which a flow of constant vorticity density is embedded in ...
Consistent estimation of distributions with type II bias with applications in competing

El Barmi, Hammou; Mukerjee, Hari (Institute of Mathematical Statistics, 2004-02)

A random variable X is symmetric about 0 if X and -X have the same distribution. There is a large literature on the estimation of a distribution function (DF) under the symmetry restriction and tests for checking this ...
The multi-layer free boundary problem for the p-Laplacian in convex domains

Acker, Andrew; Henrot, Antoine; Poghosyan, Mikayel; Shahgholian, Henrik (European Mathematical Society, 2004-08-21)

The main result of this paper concerns existence of classical solutions to the multi-layer Bernoulli free boundary problem with nonlinear joining conditions and the p-Laplacian as gov- erning operator. The present treatment ...
Geometry of nonlinear connections

Parker, Phillip E.; Del Riego, L. (Elsevier Science B.V., Amsterdam, 2004-08-28)

We show that locally diffeomorphic exponential maps can be defined for any second-order differential equation, and give a (possibly nonlinear) covariant derivative for any (possibly nonlinear) connection. We introduce ...
Equilibrium configurations for a floating drop

Elcrat, Alan; Neel, Robert; Siegel, David (Birkhäuser-Verlag, Basel, 2004-12-01)

If a drop of fluid of density ρ1 rests on the surface of a fluid of density ρ2 below a fluid of density ρ0, ρ0 < ρ1 < ρ2, the surface of the drop is made up of a sessile drop and an inverted sessile drop which match an ...
Conjugate loci of pseudo-Riemannian 2-step nilpotent Lie groups with nondegenerate center

Jang, Changrim; Parker, Phillip E. (Springer, 2005)

We determine the complete conjugate locus along all geodesics parallel or perpendicular to the center (Theorem 2.3). When the center is one-dimensional we obtain formulas in all cases (Theorem 2.5), and when a certain ...
Inferences under a stochastic ordering constraint: The k-sample case

El Barmi, Hammou; Mukerjee, Hari (American Statistical Association, 2005-03)

If X1 and X2 are random variables with distribution functions F1 and F2, then X1 is said to be stochastically larger than X2 if F1 ≤ F2. Statistical inferences under stochastic ordering for the two-sample case has a long ...
On the non-starlikeness of solutions to the starlike interior wake problem

Acker, Andrew (American Mathematical Society, 2005-07-18)

We study examples of the starlike interior “wake problem” for which no starlike solution exists relative to the natural star center of the problem. These examples show that the main result of D.E. Tepper in “A mathematical ...
Conjectures in inverse boundary value problems for quasilinear elliptic equations

Sun, Ziqi (Department of Mathematics of the Universidad de la Frontera Temuco-Chile and the Department of Mathematics of the Universidade Federal de Pernambuco, Recife-Brazil, 2005-12)

Inverse boundary value problems originated in early 80’s, from the contribution of A.P. Calderon on the inverse conductivity problem [C], in which one attempts to recover the electrical conductivity of a body by means ...
Restricted estimation of the cumulative incidence functions corresponding to competing risks

El Barmi, Hammou; Mukerjee, Hari (Institute of Mathematical Statistics, 2006)

In the competing risks problem, an important role is played by the cumulative incidence function (CIF), whose value at time t is the probability of failure by time t from a particular type of failure in the presence of ...
Matched-pairs tests of homogeneity with applications to homologous nucleotide sequences

Ababneh, Faisal; Jermiin, Lars S.; Ma, Chunsheng; Robinson, John (Oxford University Press, 2006-05-15)

Motivation: Most phylogenetic methods assume that the sequences of nucleotides or amino acids have evolved under stationary, reversible and homogeneous conditions. When these assumptions are violated by the data, there ...
Vertical blow ups of capillary surfaces in R3, part one: convex corners

Jeffres, Thalia; Lancaster, Kirk (Texas State University - San Marcos, 2007-11)

One technique which is useful in the calculus of variations is that of “blowing up”. This technique can contribute to the understanding of the boundary behavior of solutions of boundary value problems, especially when they ...
Recent developments on the construction of spatio-temporal covariance models

Ma, Chunsheng (Springer-Verlag, 2008)

This paper briefly surveys some recent advances on how to construct spatio-temporal covariance functions, with the emphasis on the methods which can be used to derive covariance functions but not on a summary list of ...
Order restricted inference for comparing the cumulative incidence of a competing risk over several populations

El Barmi, Hammou; Kochar, Subhash; Mukerjee, Hari (Institute of Mathematical Statistics, 2008)

There is a substantial literature on testing for the equality of the cumulative incidence functions associated with one specific cause in a competing risks setting across several populations against specific or all ...
Rational covariance functions for nonstationary random fields

Ma, Chunsheng (IEEE, 2008-02)

This correspondence propose rational-type covariance functions for nonstationary Gaussian stochastic processes or random fields, which are rational functions of given variograms, typically have long range dependence, ...