Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network

Open Access. Powered by Scholars. Published by Universities.®

Articles 31 - 52 of 52

Full-Text Articles in Entire DC Network

On The Existence Of Multiple Positive Solutions For A Semilinear Problem In Exterior Domains, Yinbin Deng, Yi Li May 2002

On The Existence Of Multiple Positive Solutions For A Semilinear Problem In Exterior Domains, Yinbin Deng, Yi Li

Yi Li

In this paper, we study the existence and nonexistence of multiple positive solutions for problem where Ω=N\ω is an exterior domain in N, ωN is a bounded domain with smooth boundary, and N>2. μ⩾0, p>1 are some given constants. K(x) satisfies: K(x)∈Cαloc(Ω) and ∃C, ϵ, M>0 such that |K(x)|⩽C |x|l for any |x|⩾M, with l⩽ −2−ϵ. Some existence and …


Separation Property Of Solutions For A Semilinear Elliptic Equation, Yi Liu, Yi Li, Yinbin Deng Jan 2000

Separation Property Of Solutions For A Semilinear Elliptic Equation, Yi Liu, Yi Li, Yinbin Deng

Yi Li

In this paper, we study the following elliptic problem[formula]where K(x) is a given function in Cα(n\0) for some fixed α∈(0, 1), p>1 is a constant. Some existence, monotonicity and asymptotic expansion at infinity of solutions of (*) are discussed.


Hopf Bifurcation In Models For Pertussis Epidemiology, Herbert W. Hethcote, Yi Li, Zhujun Jing Dec 1999

Hopf Bifurcation In Models For Pertussis Epidemiology, Herbert W. Hethcote, Yi Li, Zhujun Jing

Yi Li

Pertussis (whooping cough) incidence in the United States has oscillated with a period of about four years since data was first collected in 1922. An infection with pertussis confers immunity for several years, but then the immunity wanes, so that reinfection is possible. A pertussis reinfection is mild after partial loss of immunity, but the reinfection can be severe after complete loss of immunity. Three pertussis transmission models with waning of immunity are examined for periodic solutions. Equilibria and their stability are determined. Hopf bifurcation of periodic solutions around the endemic equilibrium can occur for some parameter values in two …


Generalized Averages For Solutions Of Two-Point Dirichlet Problems, Philip Korman, Yi Li Nov 1999

Generalized Averages For Solutions Of Two-Point Dirichlet Problems, Philip Korman, Yi Li

Yi Li

For very general two-point boundary value problems we show that any positive solution satisfies a certain integral relation. As a consequence we obtain some new uniqueness and multiplicity results.


Axiomatic Approach For Quantification Of Image Resolution, Ge Wang, Yi Li Oct 1999

Axiomatic Approach For Quantification Of Image Resolution, Ge Wang, Yi Li

Yi Li

Image resolution is the primary parameter for performance characterization of any imaging system. In this work, we present an axiomatic approach for quantification of image resolution, and demonstrate that a good image resolution measure should be proportional to the standard deviation of the point spread function of an imaging system.


Positive Solutions To Semilinear Problems With Coefficient That Changes Sign, Nguyen Phuong Cac, Juan A. Gatica, Yi Li Aug 1999

Positive Solutions To Semilinear Problems With Coefficient That Changes Sign, Nguyen Phuong Cac, Juan A. Gatica, Yi Li

Yi Li

No abstract provided.


Eigenfunction And Harmonic Function Estimates In Domains With Horns And Cusps, Michael Cranston, Yi Li Jan 1997

Eigenfunction And Harmonic Function Estimates In Domains With Horns And Cusps, Michael Cranston, Yi Li

Yi Li

No abstract provided.


Existence And Bifurcation Of The Positive Solutions For A Semilinear Equation With Critical Exponent, Yinbin Deng, Yi Li Sep 1996

Existence And Bifurcation Of The Positive Solutions For A Semilinear Equation With Critical Exponent, Yinbin Deng, Yi Li

Yi Li

In this paper, we consider the semilinear elliptic equation[formula]Forp=2N/(N−2), we show that there exists a positive constantμ*>0 such that (∗)μpossesses at least one solution ifμ∈(0, μ*) and no solutions ifμ>μ*. Furthermore, (∗)μpossesses a unique solution whenμ=μ*, and at least two solutions whenμ∈(0, μ*) and 2<NN⩾6, under some monotonicity conditions onf((1.6)) we show that there exist two constants 0<μ**μ**<μ* such that problem (∗)μ …


High-Resolution Ultraviolet Spectroscopy Of Jupiter's Aurora With The Hubble Space Telescope, Y. H. Kim, John J. Caldwell, Jane L. Fox Jul 1995

High-Resolution Ultraviolet Spectroscopy Of Jupiter's Aurora With The Hubble Space Telescope, Y. H. Kim, John J. Caldwell, Jane L. Fox

Jane L. Fox

In 1993 June and July, we obtained 18 spectra of Jupiter's aurora in the wavelength range 1586-1620 Å using the Goddard High Resolution Spectrograph on board the Hubble Space Telescope (HST). The field of view for each observation was 2" × 2". There were 14 spectra of the northern and four spectra of the southern auroral ovals. The spectra are dominated by vibrational-rotational lines of the H2 Lyman band system, from which we have determined H2 rotational temperatures which correspond to the altitude region where most of the auroral emission originates. Intense emission was observed in …


Electron Energy Loss In Oxygen Plasmas, G. A. Victor, John C. Raymond, Jane L. Fox Nov 1994

Electron Energy Loss In Oxygen Plasmas, G. A. Victor, John C. Raymond, Jane L. Fox

Jane L. Fox

The results of calculations of the energy deposition of energetic electrons in oxygen plasmas are given. In a pure oxygen plasma even with large fractional ionization, much of the electron energy results in the production of additional ionization and excited electronic states. Results are given for separate calculations using theoretical and experimental cross sections for the important O I excitations of 1S and 1D because the theoretical and experimental data are not in agreement. These results are useful for understanding the spectra of oxygen-rich supernova remnants.


Uniqueness Of Radial Solutions Of Semilinear Elliptic Equations, Man Kam Kwong, Yi Li Jan 1993

Uniqueness Of Radial Solutions Of Semilinear Elliptic Equations, Man Kam Kwong, Yi Li

Yi Li

E. Yanagida recently proved that the classical Matukuma equation with a given exponent has only one finite mass solution. We show how similar ideas can be exploited to obtain uniqueness results for other classes of equations as well as Matukuma equations with more general coefficients.


Radial Symmetry Of Positive Solutions Of Nonlinear Elliptic Equations In Rn, Yi Li, Wei-Ming Ni Jan 1993

Radial Symmetry Of Positive Solutions Of Nonlinear Elliptic Equations In Rn, Yi Li, Wei-Ming Ni

Yi Li

No abstract provided.


On The Positive Solutions Of The Matukuma Equation, Yi Li Jan 1993

On The Positive Solutions Of The Matukuma Equation, Yi Li

Yi Li

No abstract provided.


On The Asymptotic Behavior And Radial Symmetry Of Positive Solutions Of Semilinear Elliptic Equations In R N Ii. Radial Symmetry, Yi Li, Wei-Ming Ni Jan 1992

On The Asymptotic Behavior And Radial Symmetry Of Positive Solutions Of Semilinear Elliptic Equations In R N Ii. Radial Symmetry, Yi Li, Wei-Ming Ni

Yi Li

The main purpose of this paper is to prove Theorems 1 and 2 of the preceding paper, Part I, together with their extensions and related symmetry results. To make this part essentially self-contained, we shall apply the method developed in Section 2 to equations with radial symmetry. Combining the asymptotic behavior and the "moving plane" technique, we are then able to obtain the desired results.


On The Asymptotic Behavior And Radial Symmetry Of Positive Solutions Of Semilinear Elliptic Equations In Rn. I. Asymptotic Behavior, Yi Li, Wei-Ming Ni Jan 1992

On The Asymptotic Behavior And Radial Symmetry Of Positive Solutions Of Semilinear Elliptic Equations In Rn. I. Asymptotic Behavior, Yi Li, Wei-Ming Ni

Yi Li

No abstract provided.


Boundary C1, Α Regularity For Variational Inequalities, Fang-Hua Lin, Yi Li Aug 1991

Boundary C1, Α Regularity For Variational Inequalities, Fang-Hua Lin, Yi Li

Yi Li

No abstract provided.


On The Existence And Symmetry Properties Of Finite Total Mass Solutions Of The Matukuma Equation, The Eddington Equation And Their Generalizations, Yi Li, Wei-Ming Ni Jan 1989

On The Existence And Symmetry Properties Of Finite Total Mass Solutions Of The Matukuma Equation, The Eddington Equation And Their Generalizations, Yi Li, Wei-Ming Ni

Yi Li

No abstract provided.


Remarks On A Semilinear Elliptic Equation On Rn, Yi Li Jul 1988

Remarks On A Semilinear Elliptic Equation On Rn, Yi Li

Yi Li

No abstract provided.


On Conformal Scalar Curvature Equations In Rn, Yi Li, Wei-Ming Ni Jan 1988

On Conformal Scalar Curvature Equations In Rn, Yi Li, Wei-Ming Ni

Yi Li

No abstract provided.


Cooling By Immersion In Liquid Nitrogen, Thomas W. Listerman, Thomas A. Boshinski, Lynn F. Knese Jun 1986

Cooling By Immersion In Liquid Nitrogen, Thomas W. Listerman, Thomas A. Boshinski, Lynn F. Knese

Thomas Listerman

When an object is cooled by immersion in a liquid, there is an unexpected increase in the violence of boiling just before the boiling stops. Most people seem fascinated by this phenomenon yet few are acquainted with its explanation in terms of a change in the heat‐transfer mechanism from film boiling to nucleate boiling. We have developed two variations of an intermediate level undergraduate laboratory experiment to measure the heat‐transfer rate after a sample is immersed in liquid nitrogen. The temperature of the sample, as measured by a thermocouple, is recorded as a function of time using either a potentiometer …


Determining The Temperature-Dependent Characteristic Temperature Of Beryllium From Electrical Resistance Measurements, Thomas W. Listerman, Xiao-Li Zhou May 1985

Determining The Temperature-Dependent Characteristic Temperature Of Beryllium From Electrical Resistance Measurements, Thomas W. Listerman, Xiao-Li Zhou

Thomas Listerman

We have developed an intermediate-level laboratory experiment to determine the temperature- dependent characteristic temperature of beryllium. The apparatus used to measure the resistance of a beryllium wire sample between liquid nitrogen and room temperatures was simple. The characteristic temperatures obtained from these data using the Block-Grüneisen model are in reasonable agreement with literature values obtained from resistivity and heat capacity experiments. The experiment introduced students to cryogenic and computer data analysis techniques and forced them to extend their knowledge of the theory of electrical resistance and of characteristic temperatures.


Young's Modulus And Internal Damping In A Vibrating Rod, H. M. Simpson, Paul J. Wolfe Jun 1975

Young's Modulus And Internal Damping In A Vibrating Rod, H. M. Simpson, Paul J. Wolfe

Paul J. Wolfe

A high‐Q mechanical oscillator in the form of a metallic rod with an eddy current driver is described. With this oscillator and a simple crystal transducer the characteristics of a mechanical oscillator can be easily studied and Young’s modulus for the metal can be found. With an inexpensive FM transducer system the internal damping of the metal can also be measured.