Journal Articles, Hindawi Press

Permanent URI for this collection

https://hdl.handle.net/10919/78797

Browse

Now showing 1 - 20 of 302

k-space function spaces
McCoy, Robert A. (Hindawi, 1980-01-01)
A study is made of the properties on X which characterize when Cπ(X) is a k-space, where Cπ(X) is the space of real-valued continuous functions on X having the topology of pointwise convergence. Other properties related to the k-space property are also considered.
Peano compactifications and property metric spaces
Dickman, R. F. (Hindawi, 1980-01-01)
Let (X,d) denote a locally connected, connected separable metric space. We say the X is S-metrizable provided there is a topologically equivalent metric ρ on X such that (X,ρ) has Property S, i.e. for any ϵ>0, X is the union of finitely many connected sets of ρ-diameter less than ϵ. It is well-known that S-metrizable spaces are locally connected and that if ρ is a Property S metric for X, then the usual metric completion (X˜,ρ˜) of (X,ρ) is a compact, locally connected, connected metric space, i.e. (X˜,ρ˜) is a Peano compactification of (X,ρ). There are easily constructed examples of locally connected connected metric spaces which fail to be S-metrizable, however the author does not know of a non-S-metrizable space (X,d) which has a Peano compactification. In this paper we conjecture that: If (P,ρ) a Peano compactification of (X,ρ|X), X must be S-metrizable. Several (new) necessary and sufficient for a space to be S-metrizable are given, together with an example of non-S-metrizable space which fails to have a Peano compactification.
Influence of wall waviness on friction and pressure drop in channels
Vajravelu, K.; Nayfeh, Ali H. (Hindawi, 1981-01-01)
An attention has been given to investigate the flow behavior of anincompressible viscous fluid confined in horizontal wavy channels and set in motion due to the movement of the upper wall and the pressure differences. The governing equations have been solved analytically as well as numerically subject to the relevant boundary conditions by assuming that the solution consists of two parts: a mean part and a disturbance or perturbed part. For small and moderate Reynolds numbers, the analytical solution for the perturbed part has been found to be in good agreement with the numerical one. The effects of Reynolds number, the pressure gradient parameter, and the undulation wavenumber on friction and pressure drop are found to be quite significant. In addition to the flow behavior for both long and short waves and for large Reynolds numbers, the effect of the wall waviness on friction and pressure drop has been examined forany arbitrary amplitude of the wavy wall.
Note on a role for entire functions of the classes and
Prather, Carl L. (Hindawi, 1981-01-01)
We use the B and B* operators of Levin on the Classes P and P* and a comparison principle to prove a Gauss-Lucas Theorem for differential operators. The connection with the determination of final sets for differential operators is then clarified.
Complete function spaces
McCoy, Robert A. (Hindawi, 1983-01-01)
A study is made of certain completeness properties of the space of allcontinuous real-valued functions on a space, where this function space has the compact-open topology.
Editorial: ‘To err is human, it takes a computer to really foul things up!’*
Stewart, Kent K. (Hindawi, 1985-01-01)
Fine topology on function spaces
McCoy, Robert A. (Hindawi, 1986-01-01)
This paper studies the topological properties of two kinds of fine topologies on the space C(X,Y) of all continuous functions from X into Y.
A note on best approximation and invertibility of operators on uniformly convex Banach spaces
Holub, James R. (Hindawi Publishing Corp, 1991-01-01)
It is shown that if X is a uniformly convex Banach space and S a bounded linear operator onX for which ?I-S?=1, then S is invertible if and only if ?I-12S? <1. From this it follows thatif S is invertible on X then either (i) dist(I,[S])<1, or (ii) 0 is the unique best approximation toI from [S], a natural (partial) converse to the well-known sufficient condition for invertibility thatdist(I,[S])<1.
Commutative rings with homomorphic power functions
Dobbs, David E.; Kiltinen, John O.; Orndorff, Bobby J. (Hindawi, 1992-01-01)
A (commutative) ring R (with identity) is called m-linear (for an integer m≥2) if (a+b)m=am+bm for all a and b in R. The m-linear reduced rings are characterized, with special attention to the finite case. A structure theorem reduces the study of m-linearity to the case of prime characteristic, for which the following result establishes an analogy with finite fields. For each prime p and integer m≥2 which is not a power of p, there exists an integer s≥m such that, for each ring R of characteristic p, R is m-linear if and only if rm=rps for each r in R. Additional results and examples are given.
Topologies between compact and uniform convergence on function spaces
Kundu, S.; McCoy, Robert A. (Hindawi, 1993-01-01)
This paper studies two topologies on the set of all continuous real-valued functionson a Tychonoff space which lie between the topologies of compact convergence and uniformconvergence.
Derivation of Equations for Flexible Multibody Systems in Terms of Quasi-Coordinates from the Extended Hamilton’s Principle
Meirovitch, L. (Hindawi, 1993-01-01)
Early derivations of the equations of motion for single rigid bodies, single flexible bodies, and flexible multibody systems in terms of quasi-coordinates have been carried out in two stages. The first consists of the use of the extended Hamilton’s principle to derive standard Lagrange’s equations in terms of generalized coordinates and the second represents a transformation of the Lagrange’s equations to equations in terms of quasi-coordinates. In this article, hybrid (ordinary and partial) differential equations for flexible multibody systems are derived in terms of quasi-coordinates directly from the extended Hamilton's principle. The approach has beneficial implications in an eventual spatial discretization of the problem.
Block-Level Logic Extraction from CMOS VLSILayouts
Bhasin, Inderpreet; Tront, Joseph G. (Hindawi, 1994-01-01)
This paper describes a Prolog based Block Extraction System (ProBES) which converts a transistor level descriptionof a CMOS circuit into a logic block level description. The operation of ProBES is conceptually similar to thatof a circuit extractor. However, whereas a circuit extractor is used to identify circuit primitives such as transistors,resistors and capacitors from the geometrical information in a mask level layout description, ProBES can be usedto identify predefined gates and logic blocks in a CMOS transistor network. ProBES operates according to thecircuit hierarchy. Basic gates such as inverters, transmission-gates, nands, nors, etc. are identified first. Logicblocks composed of these gates are then identified. More complex blocks which contain blocks already identifiedare recognized next and so on. ProBES is meant to be used as an aid in the verification of logic design. It canprovide a connectivity check for a circuit.
An Efficient Automatic Test Pattern Generator forStuck-Open Faults in CMOS Combinational Circuits
Lee, Hyung K.; Ha, Dong S. (Hindawi, 1994-01-01)
In this paper, we describe a highly efficient automatic test pattern generator for stuck-open (SOP) faults, calledSOPRANO, in CMOS combinational circuits. The key idea of SOPRANO is to convert a CMOS circuit into anequivalent gate level circuit and SOP faults into the equivalent stuck-at faults. Then SOPRANO derives testpatterns for SOP faults using a gate level test pattern generator. Several techniques to reduce the test set sizeare introduced in SOPRANO. Experimental results performed on eight benchmark circuits show that SOPRANOachieves high SOP fault coverage and short processing time.
Parametrically Excited Nonlinear Two-Degree-of-Freedom Systems with Repeated Natural Frequencies
Nayfeh, Ali H.; Chin, C.; Mook, Dean T. (Hindawi, 1995-01-01)
The method of normal forms is used to study the nonlinear response of two-degree-of-freedom systems with repeated natural frequencies and cubic nonlinearity to a principal parametric excitation. The linear part of the system has a nonsemisimple one-to-one resonance. The character of the stability and various types of bifurcation including the formation of a homoclinic orbit are analyzed. The results are applied to the flutter of a simply supported panel in a supersonic airstream.
Mapping Nonsquare and Unevenly Spaced 2-D SLDV Data of an Aircraft Fuselage by Using Spatial DFT-IDFT Techniques
Li, William Xinzuo; Mitchell, Larry D.; Lu, Min-Fu; Neumann, Michael L. (Hindawi, 1996-01-01)
The scanning laser Doppler vibrometry (SLDV) technique provides velocities of a structure at 2-dimensional (2-D) angularly evenly spaced (in the laser scanning sense) data points. This causes an unevenly spaced data point distribution on the surface of the test structure. In many cases evenly spaced data point distribution with square or rectangular grids is highly desirable. In this study the SLDV velocity data of a partial surface area of an aircraft fuselage were mapped to truly spatial evenly spaced coordinates by using the spatial DFT-IDFT technique with minimum distortion. This 2-D data mapping technique certainly is not limited to the fuselage, hut can he very useful for many other 3-D structures.
Effects of anti-inflammatory drugs on fever and neutrophilia induced by Clostridium difficile toxin B
Cardoso, R. A.; Melo Fihlo, A. A.; Melo, M. C. C.; Lyerly, D. M.; Wilkins, Tracy D.; Lima, A. A. M.; Ribeiro, R. A.; Souza, G. E. P. (Hindawi Publishing Corporation, 1996-06)
This study investigated the ability of Clostridium difficile toxin B, isolated from the VPI 10463 strain, to induce fever and neutrophilia in rats. Intravenous injection of toxin B (0.005-0.5 mu g/kg) evoked a dose-dependent increase in body temperature. The febrile response to 0.5 mu g/kg of the toxin started in 2.5 h, peaked at 5 h, and subsided fully within 24 h. Toxin B also induced a dose-dependent neutrophilia. Pretreatment with indomethacin (2 mg/kg, i.p.) did not affect the neutrophilia induced by toxin B, but significantly reduced the febrile response measured 4 to 8 h after toxin B injection. Dexamethasone (0.5 mg/kg) also markedly diminished the febrile response induced by toxin B. These results show that Clostridium difficile toxin B induced a febrile response susceptible to inhibition by dexamethasone and indomethacin. Furthermore, they suggest that prostaglandins are not involved in the neutrophilia caused by this toxin.
Dynamic Response of Cantilevered Thin-Walled Beams to Blast and Sonic-Boom Loadings
Librescu, Liviu; Na, Sungsoo (Hindawi, 1998-01-01)
Nonlinear Response of Cantilever Beams to Combination and Subcombination Resonances
Nayfeh, Ali H.; Arafat, Haider N. (Hindawi, 1998-01-01)
The nonlinear planar response of cantilever metallic beams to combination parametric and external subcombination resonances is investigated, taking into account the effects of cubic geometric and inertia nonlinearities. The beams considered here are assumed to have large length-to-width aspect ratios and thin rectangular cross sections. Hence, the effects of shear deformations and rotatory inertia are neglected. For the case of combination parametric resonance, a two-mode Galerkin discretization along with Hamilton’s extended principle is used to obtain two second-order nonlinear ordinary-differential equations of motion and associated boundary conditions. Then, the method of multiple scales is applied to obtain a set of four first-order nonlinear ordinary-differential equations governing the modulation of the amplitudes and phases of the two excited modes. For the case of subcombination resonance, the method of multiple scales is applied directly to the Lagrangian and virtual-work term. Then using Hamilton’s extended principle, we obtain a set of four first-order nonlinear ordinary-differential equations governing the amplitudes and phases of the two excited modes. In both cases, the modulation equations are used to generate frequency- and force-response curves. We found that the trivial solution exhibits a jump as it undergoes a subcritical pitchfork bifurcation. Similarly, the nontrivial solutions also exhibit jumps as they undergo saddle-node bifurcations.
Investigation of Subcombination Internal Resonances in Cantilever Beams
Arafat, Haider N.; Nayfeh, Ali H. (Hindawi, 1998-01-01)
Activation of subcombination internal resonances in transversely excited cantilever beams is investigated. The effect of geometric and inertia nonlinearities, which are cubic in the governing equation of motion, is considered. The method of time-averaged Lagrangian and virtual work is used to determine six nonlinear ordinary-differential equations governing the amplitudes and phases of the three interacting modes. Frequency- and force-response curves are generated for the case ω ≈ ω4 ≈ 1/2(ω2 + ω5). There are two possible responses: single-mode and three-mode responses. The single-mode periodic response is found to undergo supercritical and subcritical pitchfork bifurcations, which result in three-mode interactions. In the case of three-mode responses, there are conditions where the low-frequency mode dominates the response, resulting in high-amplitude quasiperiodic oscillations.
Neural Network Identification and Control of a Parametrically Excited Structural Dynamic Model of an F-15 Tail Section
El-Badawy, Ayman A.; Nayfeh, Ali H.; VanLandingham, Hugh F. (Hindawi, 2000-01-01)
We investigated the design of a neural-network-based adaptive control system for a smart structural dynamic model of the twin tails of an F-15 tail section. A neural network controller was developed and tested in computer simulation for active vibration suppression of the model subjected to parametric excitation. First, an emulator neural network was trained to represent the structure to be controlled and thus used in predicting the future responses of the model. Second, a neurocontroller to determine the necessary control action on the structure was developed. The control was implemented through the application of a smart material actuator. A strain gauge sensor was assumed to be on each tail. Results from computer-simulation studies have shown great promise for control of the vibration of the twin tails under parametric excitation using artificial neural networks.

Browse

Browsing Journal Articles, Hindawi Press by Issue Date

Results Per Page

Sort Options