| Inverse Problems, Control and Modeling in the Presence of Uncertainty |
30 OCT 2007 |
41 pages |
| Authors:
H. T. Banks; K. Ito; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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 | We report progress on the development of methods in a number of specific areas of application including static, non-cooperative games related to counter- and counter-counter-electromagnetic interrogation of targets, modeling of complex viscoelastic polymeric materials, stochastic and deterministic models for complex networks and development of inverse problem methodologies (generalized sensitivity functions; asymptotic standard errors) for estimation of infinite dimensional functional parameters including probability measures and temporal/spatial dependent functions in complex nonlinear ... |
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| Determination of Interrogating Frequencies to Maximize Electromagnetic Backscatter from Objects with Material Coatings |
27 AUG 2005 |
28 pages |
| Authors:
H. T. Banks; K. Ito; J. Toivanen; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| The electromagnetic backscattering of a crosscut of a cruise missile coated by a thin homogeneous layer made of radar absorbent material is modeled using a finite element method. Based on the radar cross section and a reflection coefficient, optimization problems are formulated for evaders and interrogators leading to optimal material parameters for the coating and optimal monostatic radar operating frequencies, respectively. Optimal coating materials are constructed for several radar frequencies. ... |
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| Material Surface Design to Counter Electromagnetic Interrogation of Targets |
08 DEC 2004 |
32 pages |
| Authors:
H. T. Banks; K. Ito; G. M. Kepler; J. A. Toivanen; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| Utilization of controllable ferroelectric and ferromagnetic layers coating a conducting object to provide an attenuation capability against electromagnetic interrogation is discussed. The problem is formulated as a differential game and/or a robust optimization. The scattered field due to interrogation can be attenuated with the assumption of an uncertainty in the interrogation wave numbers. The controllable layer composed of ferromagnetic and ferroelectric materials [9, 10] is incorporated in a mathematical formulation ... |
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| Interaction of Electron Vortices under the Influence of Background Vorticity Distribution |
24 JUN 2002 |
10 pages |
| Authors:
Y. Kiwamoto; K. Ito; A. Sanpei; Y. Soga; T. Yuyama; KYOTO UNIV (JAPAN)
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| We report experimental studies on vortex dynamics carried out recently in Kyoto University by using electron plasmas that are trapped in the Malmberg configuration with variety of initial configurations. This report includes (I) relaxation of many-clump dynamic states to "crystallization", (2) single clump dynamics in a background vorticity distribution. (3) two-clump interaction in a low-level background vorticity distribution, and (4) accelerated crystallization" of three clumps in a background vorticity distribution. ... |
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| Electron Vortex Dynamics and Two-Dimensional Field Analysis |
24 JUN 2002 |
6 pages |
| Authors:
K. Ito; A. Sanpei; Y. Kiwamoto; KYOTO UNIV (JAPAN)
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| In recent paper (K. Ito, el al., Jpn. J. Appl. Phys. 40, 2558 (2001), we present a fast and sufficiently accurate procedure to construct the potential and the electric field distribution from the observed electron density distribution in two-dimensional plane. Using this procedure, we obtain quantitative agreement between the observed velocity of the clump motion and the calculated velocity of that determined by the field analysis. in addition, the strong ... |
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| A Computational Model for Sound Field Absorption by Acoustic Arrays (revision 6) |
24 JUL 2001 |
20 pages |
| Authors:
H. T. Banks; D. G. Cole; K. M. Furati; K. Ito; G. A. Pinter; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| In this paper, the authors discuss the sound absorption property of arrays of micro-acoustic actuators at a control surface. They use the wave equation over the half plane for the velocity potential with a boundary dissipation by a proportional pressure feedback law along the half plane boundary. The feedback gain over the array is described by a distributed shape function. They develop a computational method based on the Fourier transform ... |
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| Real-Time Process Monitoring by P-Polarized Reflectance Spectroscopy and Closed-Loop Control of Vapor Phase Epitaxy |
2000 |
21 pages |
| Authors:
H. T. Banks; N. Dietz; K. Ito; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| Controlling and optimizing growth processes require improved methods of characterization and understanding of decomposition pathways and surface reaction kinetics. They also require the development of advanced nonlinear filtering and feedback control concepts. This contribution describes results on real-time optical monitoring of thin film growth processes by ppolarized reflectance (PR) utilizing a pulsed chemical beam epitaxy (PCBE) approach, where the growth surface is sequentially exposed to organometallic precursors. Under these conditions ... |
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| Dynamic Simulation of the Temporal Response of Microstructure Formation in Magnetorheological Fluids |
23 AUG 1999 |
11 pages |
| Authors:
H. V. Ly; K. Ito; H. T. Banks; M. R. Jolly; F. Reitich; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| Efficient numerical simulations of microstructure development in magnetorheological (MR) fluids are conducted. The simulations, which are based upon a fast multipole algorithm, treat the magnetic inclusions as two-dimensional continuum magnetic entities. The development of microstructure is quantified by computing and recording the time evolution of the effective permeability of composite fluid. Such a principle has been previously exploited for the experimental measurements of microstructure development (Jolly, Bender and Mathers, ERMR'97, ... |
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| Real-time Optical Control of Ga(1-x)In(x)P Film Growth |
AUG 1999 |
10 pages |
| Authors:
N. Dietz; V. Woods; K. Ito; I. Lauko; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF PHYSICS
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| This paper describes results on open- and closed-loop controlled growth of epitaxial GaP/Ga(1-x)In(x)P heterostructures on Si(001) substrates. The layers are grown in a low pressure pulsed chemical beam epitaxy (PCBE) reactor utilizing real time optical p-polarized reflectance (PRS) probing. The results of the implemented closed loop controlled growth favorably compare to the films grown using pre-designed source injection profiles based on an experimental data base. |
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| Real-Time Optical Control of Ga1-xInxP Film Growth by P-Polarized Reflectance |
1999 |
16 pages |
| Authors:
N. Dietz; V. Woods; K. Ito; I. Lauko; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| The engineering of advanced optoelectronic integrated circuits implies the stringent control of thickness and composition. These demands led to the development of surface-sensitive real-time optical sensors that are able to move the control point close to the point where the growth occurs- which in a chemical beam epitaxy process is the surface reaction layer (SRL) built up of physisorbed and chemisorbed precursor fragments between the ambient and film interface. In ... |
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| Adaptive Compensators for Perturbed Positive Real Infinite Dimensional Systems |
03 JUN 1998 |
22 pages |
| Authors:
R. F. Curtain; M. A. Demetriou; K. Ito; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| The aim of this investigation is to construct an adaptive observer and an adaptive compensator for a class of infinite dimensional plants having a known exogenous input and a structured perturbation with an unknown constant parameter such as the case of static output feedback with an unknown gain. The adaptive observer uses the nominal dynamics of the unperturbed plant and an adaptation law based on the Lyapunov redesign method. We ... |
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| Adaptive Observers for Structurally Perturbed Positive Real Delay Systems |
1998 |
8 pages |
| Authors:
M. A. Demetriou; R. F. Curtain; K. Ito; WORCESTER POLYTECHNIC INST MA DEPT OF MECHANICAL ENGINEERING
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| The aim of this investigation is to construct an adaptive observer for a class of muiltivariable delay systems having a known exogenous input and a structured perturbation with an unknown constant parameter such as the case of static output feedback with an unknown gain. The adaptive observer uses the nominal dynamics of the unperturbed plant and an adaptation law based on the Lyapunov redesign method. We obtain conditions on the ... |
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| Injection-Moldable Polyimides, |
10 OCT 1994 |
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| Authors:
K. Ito
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 | Aurum injection-molded bearings, bushings, seal rings and thrust washers can be found in demanding applications such as automotive transmissions, industrial machinery, semiconductor processig equipment, and power tools. Aurum is one of the most chemically resistant advanced engineering resins, unaffected by aliphatic and aromatic hydrocarbons, ketones, and most acids and bases. It is compatible with nearly all automotive fluids--including gear oil, engine oil, gasohol, sour oil, brake oil and synthetic fuel ... |
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| Grain Boundary Properties in SrTiO3 Ceramics. |
1993 |
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| Authors:
K. Ito; S. Shibagaki; H. Haneda; J. Tanaka; S. Shirasaki; NATIONAL INST FOR RESEARCH IN INORGANIC MATERIALS IBARAKI (JAPAN)
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| The elementary distribution and oxygen diffusion near grain boundary in SrTiO3 ceramics were evaluated by using TEM, micro AES, and SIMS. According to TEM and micro AES analyses, a secondary phase was formed at the grain boundaries; its composition was estimated to be approximately Bi:Ti:O=2:2:7 with a small amount of Sr. Additives, Bi, Ca, and Na ions, diffused preferentially along grain boundaries. Oxygen grain-boundary diffusion was not so rapid as ... |
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| Development of Elevated Temperature P/M Aluminum Alloy by Rapid Solidification Processing, |
OCT 1987 |
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| Authors:
S. Yamauchi; K. Shibue; H. Sano; K. Ito; S. Inumaru
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| Al-Fe system alloys were mainly investigated from the viewpoints of solid solubility, diffusion coefficient, temperature of liquidus and material cost. The mechanical properties at the room and elevated temperature were evaluated in the various Al-Fe system alloys. Al-8Fe-2V-2Mo-1Zr alloy was found to be superior to the conventional 2618 alloy in the room and elevated temperature-tensile strength, in the thermal stability of hardness, and in the fatigue and creep properties. The ... |
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| Influence of Superplastic Prestraining on Tensile Properties of 7475 Aluminum Alloy, |
SEP 1987 |
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| Authors:
K. Ito; H. Oikawa
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| Room temperature tensile yield and ultimate tensile strengths are illustrated for 7475 specimens prestrained at 755 or 795 K at an initial strain rate of 0.0007/s. Some of the measurements were made on samples that were prestrained and quenched, while some were additionally aged at 393 K for 172.8 ks. True stress-true strain curves are shown for both prestrain temperatures for the 0.0007/s initial strain rate. |
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