Necessary and sufficient conditions for the vibrations of a bounded string with directional derivatives in the boundary conditions

2014 ◽  
Vol 50 (1) ◽  
pp. 128-131 ◽  
Author(s):  
F. E. Lomovtsev ◽  
E. N. Novikov
Keyword(s):  
Boundary Conditions ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Directional Derivatives ◽  
Necessary And Sufficient

scholarly journals Invexity of supremum and infimum functions

2002 ◽  
Vol 65 (2) ◽  
pp. 289-306 ◽  
Author(s):  
Nguyen Xuan Ha ◽  
Do Van Luu
Keyword(s):  
Sufficient Conditions ◽  
Infinite Family ◽  
Lipschitz Functions ◽  
Necessary And Sufficient Conditions ◽  
Directional Derivatives ◽  
Mathematical Programs ◽  
Sufficient Conditions For Optimality ◽  
Invex Function ◽  
Necessary And Sufficient

Under suitable assumptions we establish the formulas for calculating generalised gradients and generalised directional derivatives in the Clarke sense of the supremum and the infimum of an infinite family of Lipschitz functions. From these results we derive the results ensuring such a supremum or infimum are an invex function when all functions of the invex. Applying these results to a class of mathematical programs, we obtain necessary and sufficient conditions for optimality.

Analysis and Design of Fixed–Fixed Bistable Arch-Profiles Using a Bilateral Relationship

2019 ◽  
Vol 11 (3) ◽  
Author(s):  
Safvan Palathingal ◽  
G. K. Ananthasuresh
Keyword(s):  
Boundary Conditions ◽  
Closed Form ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Single Variable ◽  
Fixed Boundary ◽  
Analysis And Design ◽  
Bilateral Relationship ◽  
Variable Equation ◽  
Necessary And Sufficient

Arch-profiles of bistable arches, in their two force-free equilibrium states, are related to each other. This bilateral relationship is derived for arches with fixed–fixed boundary conditions in two forms: a nonlinear single-variable equation for analysis and a closed-form analytical expression for design. Some symmetrical features of shape as well as necessary and sufficient conditions for bistability are presented as corollaries. Analysis and design of arch-profiles using the bilateral relationship are illustrated through examples.

The displacement problem for elastic crystals

1989 ◽  
Vol 113 (1-2) ◽  
pp. 159-180 ◽  
Author(s):  
I. Fonseca ◽  
L. Tartar
Keyword(s):  
Boundary Conditions ◽  
Convex Function ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Displacement Boundary ◽  
Displacement Problem ◽  
Body Forces ◽  
Image Position ◽  
Necessary And Sufficient ◽  
Elastic Crystals

SynopsisIn this paper we obtain necessary and sufficient conditions for the existence of Lipschitz minimisers of a functional of the typewhere h is a convex function converging to infinity at zero and u is subjected to displacement boundary conditions. We provide examples of body forces f for which the infimum of J(.) is not attained.

scholarly journals Inverse problems for the Sturm–Liouville equation with a spectral parameter in the boundary condition

2017 ◽  
Author(s):  
Namig J. Guliyev
Keyword(s):  
Boundary Condition ◽  
Inverse Problems ◽  
Boundary Conditions ◽  
Spectral Parameter ◽  
Liouville Equation ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Eigenvalue Parameter ◽  
Sturm Liouville ◽  
Necessary And Sufficient

Inverse problems of recovering the coefficients of Sturm--Liouville problems with the eigenvalue parameter linearly contained in one of the boundary conditions are studied: (1) from the sequences of eigenvalues and norming constants; (2) from two spectra. Necessary and sufficient conditions for the solvability of these inverse problems are obtained.

scholarly journals Necessary and sufficient conditions for the strong local minimality of C1 extremals on a class of non-smooth domains

2020 ◽  
Vol 26 ◽  
pp. 49
Author(s):  
Judith Campos Cordero ◽  
Konstantinos Koumatos
Keyword(s):  
Boundary Conditions ◽  
Calculus Of Variations ◽  
Materials Science ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Local Minimality ◽  
Sufficiency Theorem ◽  
Necessary And Sufficient ◽  
Quasiconvexity At The Boundary

Motivated by applications in materials science, a set of quasiconvexity at the boundary conditions is introduced for domains that are locally diffeomorphic to cones. These conditions are shown to be necessary for strong local minimisers in the vectorial Calculus of Variations and a quasiconvexity-based sufficiency theorem is established for C1 extremals defined on this class of non-smooth domains. The sufficiency result presented here thus extends the seminal theorem by Grabovsky and Mengesha (2009), where smoothness assumptions are made on the boundary.

The extinction time of a general birth and death process with catastrophes

1986 ◽  
Vol 23 (04) ◽  
pp. 851-858 ◽  
Author(s):  
P. J. Brockwell
Keyword(s):  
Laplace Transform ◽  
Size Distribution ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Death Process ◽  
Extinction Time ◽  
Birth And Death Process ◽  
Different Types ◽  
The Laplace Transform ◽  
Necessary And Sufficient

The Laplace transform of the extinction time is determined for a general birth and death process with arbitrary catastrophe rate and catastrophe size distribution. It is assumed only that the birth rates satisfyλ0= 0,λj> 0 for eachj> 0, and. Necessary and sufficient conditions for certain extinction of the population are derived. The results are applied to the linear birth and death process (λj=jλ, µj=jμ) with catastrophes of several different types.

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