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AIAA Guidance, Navigation, and Control Conference 2005

作者： Belcastro, Celeste M. Chowdhury, Fahmida Cheng, Qi Michels, James H. Varshney, Pramod K. NASA Langley Research Center Hampton VA 23681 University of Louisiana Lafayette LA 70504 Syracuse University Syracuse NY 13244 Safety-Critical Avionics Systems Mail Stop 130 1 S. Wright St AIAA Dept. of Electrical and Computer Engineering Madison Hall R248 131 Rex Street Electrical Engineering and Computer Science 335 Link Hall

ISBN: (纸本)1563477378

Timely and reliable detection of controller malfunction is a crucial task in all control systems. In flight control, it is even more crucial, since the cost of controller malfunction is potentially very high. Aircraft Flight Control computers (FCCs) are typically implemented with redundant processing elements in order to mask random independent component failures. However, redundancy alone does not mask the effects of common-cause disturbances, such as lightning and High-Intensity Radiated Fields (HIRF), that can affect the functional integrity of all processing channels. This paper presents a distributed detection scheme with data fusion for monitoring the function of redundant processing channels of a flight critical controller during operation. Malfunctions in the system are non-Gaussian and can be detected and isolated to the control command calculation in the specific faulty channel. Three approaches for detecting errors in the control law calculations of each processor (i.e. the local detector) are presented: (1) Kalman Filter estimates are used to generate residuals which are then tested against a 3-a threshold;(2) Kalman Filter estimates are used to generate residuals which are then processed using an AR-predictive smoothing filter, and the sample variance of the raw residuals is also calculated;and (3) local detector design is based on state estimation by particle filtering. The implementation of the detection scheme using each of these approaches for the local detector in the context of distributed detection with data fusion is demonstrated using data collected during closed-loop HIRF system effects experiments on a quad-redundant FCC executing Autoland control laws under flight conditions with heavy clear air turbulence. The performance of the monitoring system using each of these local detector approaches is assessed.

关键词： Control system analysis

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Evaluation of the field-effect carrier mobility in single-grain (and polycrystalline) organic semconductors

Evaluation of the field-effect carrier mobility in single-gr...

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Complex Mediums VI: Light and Complexity

作者： Kwok, H.L. Center for Advanced Materials and Related Technology University of Victoria Victoria BC Canada Dept. of Electrical and Computer Engineering University of Victoria P.O. Box 3055 Victoria BC V8W 3P6 Canada

Mobility in single-grain and polycrystalline organic field-effect transistors (OFETs) is of interest because it affects the performance of these devices. While reasonable values of the hole mobility has been measured in pentacene OFETs, relatively speaking, our understanding of the detailed transport mechanisms is somewhat weak and there is a lack of precise knowledge on the effects of the materials parameters such as the site spacing, the localization length, the rms width of the density of states (DOS), the escape frequency, etc. This work attempts to analyze the materials parameters of pentacene OFETs extracted from data reported in the literature. In this work, we developed a model for the mobility parameter from first principle and extracted the relevant materials parameters. According to our analyses, the transport mechanisms in the OFETs are fairly complex and the electrical properties are dominated by the properties of the trap states. As observed, the single-grain OFETs having smaller values of the rms widths of the DOS (in comparison with the polycrystalline OFETs) also had higher hole mobilities. Our results showed that increasing the gate bias could have a similar but smaller effect. Potentially, increasing the escape frequency is a more effective way to raise the hole mobility and this parameter appears to be affected by changes in the molecular structure and in the degree of "disorder".

关键词： Semiconducting organic compounds

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Resonant cavity imaging biosensor

Resonant cavity imaging biosensor

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18th Annual Meeting of the IEEE Lasers and Electro-Optics Society, LEOS 2005

作者： Bergstein, David A. Irani, Rostem J. Ruane, Michael F. DeLisi, Charles Unlu, M. Selim Boston University Electrical and Computer Engineering Dept. 8 St. Mary's St. Boston MA 02215 United States Boston University Center for Advanced Genomic Technology 44 Cummington St. Boston MA United States

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ISBN: (纸本)0780392175

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String matching-based universal source codes for source networks with asymptotically zero feedback

String matching-based universal source codes for source netw...

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2005 IEEE International Symposium on Information Theory, ISIT 05

作者： Yang, En-Hui He, Da-Ke Uyematsu, Tomohiko Yeung, Raymond W. Dept. of Electrical and Computer Engineering University of Waterloo Waterloo Ont. N2L 3G1 Canada IBM T. J. Watson Research Center Yorktown Heights NY 10598 United States Dept. of Communications and Integrated Systems Tokyo Institute of Technology Ookamaya 2-12-1 Meguro-ku Tokyo 152- 8552 Japan Dept. of Information Engineering Chinese University of Hong Kong N.T. Hong Kong

ISBN: (纸本)0780391519

Consider a source network in which a finite alphabet source X = {X i}i=0∞ is to be encoded and transmitted, and another finite alphabet source Y = {Yi}i=0∞ available only to the decoder as the side information correlated with X. Traditionally the channel between the encoder and decoder in the source network is assumed to be one-way. This, together with that the encoder does not have access to Y, necessitates that the encoder knows the achievable rates before encoding. In this paper we consider universal source coding for a feedback source network in which the channel between the encoder and decoder is two-way and asymmetric. Assuming that the encoder and decoder share a random database that is independent of both X and Y, we propose a string matching-based (variable-rate) block coding algorithm with a simple progressive encoder for the feedback source network. This algorithm does not need to know the achievable rates at the beginning of encoding. It is proven that for any (X, Y) in a large class of sources which includes the class of all memoryless sources, the class of all aperiodic Markov sources, and a large class of finite-state sources as special subclasses, the average number of bits per letter transmitted from the encoder to the decoder (compression rate) goes arbitrarily close to the conditional entropy H(X|Y) of X given Y asymptotically, and the average number of bits per letter transmitted from the decoder to the encoder (feedback rate) goes to 0 asymptotically.

关键词： Block codes

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Stability analysis of iterative learning control system with interval uncertainty

Stability analysis of iterative learning control system with...

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作者： Ahn, Hyo-Sung Moore, Kevin L. Chen, Yang Quan Center for Self-Organizing and Intelligent Systems Dept. of Electrical and Computer Engineering Utah State University 4160 Old Main Hill Logan UT 84322-4160 United States Research and Technology Development Center Johns Hopkins University Applied Physics Laboratory 11100 Johns Hopkins Road Laurel MD 20723-6099 United States

ISBN: (纸本)008045108X

This paper presents a stability analysis of the iterative learning control (ILC) problem when the plant Markov parameters are subject to interval uncertainty. Using the super-vector approach to ILC, vertex Markov matrices are employed to develop sufficient conditions for both asymptotic stability and monotonic convergence of the ILC process. It is shown that Kharitonov segments between vertex matrices are not required for checking the stability of interval super-vector ILC systems, but instead checking just the vertex Markov matrices is sufficient. Copyright © 2005 IFAC.

关键词： Asymptotic stability

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Range identification for perspective dynamic systems with 3D imaging surfaces

Range identification for perspective dynamic systems with 3D...

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2005 American Control Conference, ACC

作者： Ma, Lili Chen, YangQuan Moore, Kevin L. 4160 Old Main Hill Logan UT 84322-4160 United States Center for Self-Organizing and Intelligent Systems Dept. of Electrical and Computer Engineering Utah State University 4160 Old Main Hill Logan UT 84322-4160 Research and Technology Development Center Johns Hopkins University Applied Physics Laboratory 11100 Johns Hopkins Road Laurel MD 20723-6099

Range identification using image sequence via observations from a traditional camera-type vision system has been discussed in the literature. In this paper, the camera-type planar imaging surface is extended to several well-known 3D surfaces, such as an arbitrary plane, a sphere, an ellipsoid, and a paraboloid. For a general imaging surface, the resulting perspective dynamic system is not guaranteed to preserve an affine form. In this case, most existing nonlinear observers that are applicable to the perspective dynamic system observed via a camera can not be applied for the range identification problem directly. We show via simulations that our recently proposed linear approximation observer can perform the state estimation. © 2005 AACC.

关键词： Image segmentation

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STATE-PERIODIC ADAPTIVE FRICTION COMPENSATION

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IFAC Proceedings Volumes 2005年第1期38卷 7-12页

作者： Hyo-Sung Ahn YangQuan Chen Center for Self-Organizing & Intelligent Systems (CSOIS) Dept. of Electrical and Computer Engineering UMC 4160 College of Engineering 4160 Old Main Hill Utah State University Logan UT 84322-4160 USA

This paper focuses on the adaptive friction compensation, where the friction is considered as a position-dependent disturbance. We consider the case when the desired trajectory is state (e.g., position) periodical which is of course also time periodical. The key idea of our approach is to use one trajectory past information along the state axis to update the current adaptation since the friction is state-periodic. The new method consists of two main steps: Firstly, in the first repetitive trajectory, an adaptive compensator is designed to guarantee the l 2 - stability of the overall system; and secondly, from the second repetitive trajectory and onwards, a state-periodic adaptive compensator is designed based on stored past state-dependent information. Rigorous stability analysis is presented with a simulation example.

关键词： Friction compensation state-dependent disturbance adaptive control periodic update tracking control

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Enhancement of light extraction GaN light-emitting diodes by omni-directional reflectors with ITO nanorod low-refractive-index layer

Enhancement of light extraction GaN light-emitting diodes by...

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Fifth International Conference on Solid State Lighting

作者： Kim, Jong Kyu Xi, J.-Q. Luo, Hong Cho, Jaehee Sone, Cheolsoo Park, Yongjo Fred Schubert, E. Electrical Computer and Systems Engineering Dept. Rensselaer Polytechnic Institute 110 Eighth Street Troy NY 12180 United States Dept. of Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute 110 Eighth Street Troy NY 12180 United States Photonics Program Team Samsung Advanced Institute of Technology Suwon 440-600 Korea Republic of

Enhancement of light extraction in GaN light-emitting diodes (LEDs) employing omnidirectional reflectors (ODRs) is presented. The ODR consists of GaN, ITO nanorod low-refractive-index layer, and an Ag layer. An array of ITO nanorods is deposited by oblique-angle deposition using e-beam evaporation. The refractive index of the ITO nanorods is 1.34 at 461 nm, significantly lower that that of dense ITO, which is n = 2.06 at 461 nm. It is experimentally shown that the GaN LED with GaN/ITO nanorods/Ag ODR show much better electrical properties and higher light-extraction efficiency than LEDs with Ag contact. This is attributed to enhanced reflectivity of the ODR by using an ITO low-refractive-index layer with high transparency, high conductivity, and low refractive index.

关键词： Light emitting diodes

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Algebraic H∞ design of Higher-Order Iterative Learning Controllers

Algebraic H∞ design of Higher-Order Iterative Learning Cont...

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20th IEEE International Symposium on Intelligent Control, ISIC '05 and the13th Mediterranean Conference on Control and Automation, MED '05

作者： Moore, Kevin L. Chen, Yangquan Ahn, Hyo-Sung IEEE Research and Technology Development Center Johns Hopkins University Applied Physics Laboratory 11100 Johns Hopkins Road Laurel MD 20723-6099 Dept. of Electrical and Computer Engineering Utah State University 4160 Old Main Hill Logan UT 84322-4160 United States

ISBN: (纸本)0780389360

This paper presents an H∞-based design technique for synthesis of higher-order iterative learning controllers (ILC) for plants subject to iteration-domain input/output disturbances and plant model uncertainty. Using a formulation of the higher-order ILC problem into a high-dimensional MIMO discrete-time system, it is shown how the addition of input/output disturbances and plant model uncertainty to the ILC problem can be cast into a standard H∞ framework. An algebraic approach to solving the problem in this framework is presented, resulting in a sub-optimal controller that can achieve both stability and robust performance. The key observation is that H∞ synthesis can be used for higher-order ILC design to achieve reliable performance in the presence of iteration-varying external disturbances and model uncertainty. ©2005 IEEE.

关键词： Control system analysis

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Reduced-order model-based feedback controller design for subsonic cavity flows

Reduced-order model-based feedback controller design for sub...

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43rd AIAA Aerospace Sciences Meeting and Exhibit

作者： Yuan, X. Caraballo, E. Yan, P. Özbay, H. Serrani, A. DeBonis, J. Myatt, J.H. Samimy, M. Collaborative Center of Control Science Ohio State University United States Department of Electrical and Computer Engineering Department of Mechanical Engineering United States Bilkent Univ. Dept. of Electrical and Electronics Eng. Ankara Turkey NASA Glenn's Quiet Aircraft Technology Program United States Air Force Research Laboratory Air Vehicles Directorate WPAFB United States

This paper explores feedback controller design for cavity flows based on reduced-order models derived using Proper Orthogonal Decomposition (POD) along with Galerkin projection method. Our preliminary analysis shows that the equilibrium of the POD model is unstable and a static output feedback controller cannot stabilize it. We develop Linear Quadratic (LQ) optimal state feedback controllers and LQ optimal observers for the linearized models. The linear controllers and observers are applied to the nonlinear system using simulations. The controller robustness is numerically tested with respect to different POD models generated at different forcing frequencies. An estimation for the region of attraction of the linear controllers is also provided.

关键词： Subsonic flow

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