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ANALYZING THE STABILITY BEHAVIOUR OF SOLUTIONS AND THEIR APPROXIMATIONS IN CASE OF INDEX-2 DIFFERENTIAL-ALGEBRAIC SYSTEMS - Roswitha März; Antonio R. Rodríguez-Santiesteban
When integrating regular ordinary differential equations numerically, one tries to match carefully the dynamics of the numerical algorithm with the dynamical behaviour of the true solution. The present paper deals with linear index-2 differential-algebraic systems. It is shown how knowledge pertaining to (numerical) regular ordinary differential equations applies provided a certain subspace which is closely related to the tangent space of the constraint manifold remains invariant.
Ore Subresultants in Solutions - Hoon Hong
... Recently theyhavebeenextendedtoOrepolynomials. They are defined by an expression in the coefficients of Ore polynomials. In this paper, we provide another expression for them. This expression is written in terms of the "solutions" of Ore polynomials (in "generic" case). It is a generalization of our previous paperwherewegavetheexpression fortheprincipal (formal leading) coefficients of subresultants. In this paper, we give the expressions for all the other coefficients.
Motion detection using Approximate Entropy - Phillip M. Ngan
The detection of motion from image sequences is usually performed using a time differential method or calculating the difference from a background reference image. These algorithms often perform poorly in the presence of temporal clutter. This paper describes a technique that measures the irregularity of an intensity sequence to detect motion. We demonstrate that static background, interesting motion events, and temporal clutter, can be distinguished from each other using a technique called Approximate Entropy.
Reducing False Detections in Extracting 3D Anatomical Point Landmarks - Sönke Frantz; Karl Rohr; H. Siegfried Stiehl
Applying 3D differential operators to extract point landmarks from medical images generally suffers from false detections. A considerable number of these false detections is caused by neighboring structures that are included in the region-of-interest (ROI) specified by the observer. The main contributions of this paper are two different approaches to reducing false detections resulting from neighboring structures. First, we present a statistical differential approach to selecting a suitable ROI size automatically. Second, we propose a differential approach to incorporating prior knowledge of the intensity structure at a landmark. Also, to cope with anisotropic voxel sizes in estimating partial derivatives, we...
Closed Form Solutions of Hybrid Systems - Martin V. Mohrenschildt
In this paper we present a new symbolic approach to hybrid systems. Hybrid systems are systems containing both, continuous and discrete changing quantities. We model hybrid systems using hybrid automata: Hybrid automata extend the classical notion of finite state machines by combining differential equations to model the dynamic behavior of systems with a finite control. In contrast to other approaches we consider a hybrid automata as a generalization of differential equations and develop the notion of a symbolic "closed form" solution of a hybrid automata. A closed form solution is an expression which gives the value of the quantities in...
The Nonhomomorphicity of S-boxes - Yuliang Zheng; Xian-mo Zhang
In this paper, we introduce the concept of kth-order nonhomomorphicity of mappings or S-boxes as an alternative indicator that forecasts nonlinearity characteristics of an S-box, where k 4 is even. Main results of this paper include: (1) we show that nonhomomorphicity, especially the 4th order nonhomomorphicity, can be precisely expressed by using other important nonlinear indicators of an S-box. (2) we establish tight lower and upper bounds on the nonhomomorphicity of S-boxes, (3) we identify the mean of nonhomomorphicity over all the S-boxes with the same size and the relative nonhomomorphicity of an S-box, both of which are useful in...
Documentation of the GEOS/DAS Observation Data Stream (ODS) - Arlindo Da Silva; Christopher Redder
This document describes the Observation Data Stream (ODS) format used for pre- and post-analysis station data (non-gridded). These HDF compliant files are intended to serve as input as well as output for the Goddard EOS Data Assimilation System (GEOS/DAS). This office note describes the concept of an ODS file and documents high level FORTRAN access software. It is geared to the producers and users of such data sets. On-line versions of this document are available from ftp://dao.gsfc.nasa.gov/pub/officenotes/on9501.ps.Z (postscript) ftp://niteroi.gsfc.nasa.gov/www/on9501/ods.html (HTML)
THE GENERAL TOTALLY POSITIVE MATRIX COMPLETION PROBLEM WITH FEW UNSPECIFIED ENTRIES - Shaun M. Fallat; Charles R. Johnson; Ronald L. Smith
For m-by-n partial totally positive matrices with exactly one unspecified entry, the set of positions for that entry that guarantee completability to a totally positive matrix are characterized. They are the positions (i � j), i + j 4 and the positions (i � j), i + j m + n; 2. In each case, the set of completing entries is an open (and infinite in case i = j =1ori = m, j = n) interval. In the process some new structural results about totally positive matrices are developed. In addition, the pairs of positions that guarantee completability in...
The Dynamics of Climate Agreements - Bård Harstad
I provide a novel dynamic model with private provision of public bads and investments in technologies. The analysis is tractable and the MPE unique. By adding incomplete contracts, I derive implications of and for international climate treaties. While the non-cooperative equilibrium is bad, short-term agreements are worse due to hold-up problems. A long-term agreement should be more ambitious if it is relatively short-lasting and the technological externality large. The length itself should increase in this externality. With renegotiation, the outcome is …rst best. The technological externalities are related to trade agreements, making them strategic substitutes to climate treaties.
Resource lambda-calculus: the differential viewpoint - Thomas Ehrhard
Milner’s π calculus features a clear dichotomy between replicable and non-replicable resources, very much in the spirit of Linear Logic (LL). Analyzing Milner’s encoding of the lazy λ-calculus in the π-calculus, Boudol introduced the λ-calculus with resources [1, 2] where functions can be applied to bags made of replicable and non-replicable arguments. This refinement of the syntax required to stick to a lazy reduction strategy implemented with explicit substitutions, used to postpone linear substitutions of non replicable resources. Motivated by the discovery of denotational models of LL such as  where all morphisms of the associated cartesian closed category can...
VARIATION BOUNDARY INTEGRAL EQUATION FOR FLAW SHAPE IDENTIFICATION - Rafael Gallego; Javier Suárez
In this communication a Variation Boundary Integral Equation (BIE) for the solution of identification inverse problems is presented. This equation relates the variation of the fields along the boundary with the variation of the geometry of a flaw, whose position and shape are unknown beforehand. The Variation BIE is obtained linearizing the difference between the standard BIE for the actual configuration (actual flaw) and the standard BIE for the assumed configuration. The resulting Variation BIE has not been completely derived before, to the authors knowledge. The solution of the ensuing Variation BIE is tackled by a procedure that avoids altogether...
On the non-existence of ε-uniform finite difference methods on uniform meshes for semilinear two-point boundary value problems - Paul A. Farrell; John J. H. Miller; Eugene O'Riordan; Grigori I. Shishkin
In this paper fitted finite difference methods on a uniform mesh with internodal spacing h, are considered for a singularly perturbed semilinear two point boundary value problem. It is proved that a scheme of this type with a frozen fitting factor cannot converge "-uniformly in the maximum norm to the solution of the differential equation as the mesh spacing h goes to zero. Numerical experiments are presented which show that the same result is true for a number of schemes with variable fitting factors.