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A SUCCESSIVE QUADRATIC programMING ALGORITHM FOR SDP RELAXATION OF MAX-BISECTION

appl.ed math.matics(A Journal of Chinese Universities) 2007年第4期22卷 434-440页

作者： Mu Xuewen Zhang Yaling Liu Sanyang Dept. of Appl. Math. Xidian Univ. Xi＇an 710071 China. Dept. of Comput. Sci. Xi＇an Univ. of Science and Technology Xi＇an 710054 China.

A successive quadratic programming algorithm for solving SDP relaxation of Max- Bisection is provided and its convergence result is given. The step-size in the algorithm is obtained by solving n easy quadratic equations without using the linear search technique. The numerical experiments show that this algorithm is rather faster than the interior-point method.

关键词： semidefinite programming Max-Bisection successive quadratic programming.

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ESTIMATING THE ENERGY-SOURCE AND REFLECTIVITY BY SEISMIC INVERSION

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INVERSE PROBLEMS 1995年第2期11卷 383-395页

作者： MINKOFF, SE SYMES, WW Dept. of Comput. & Appl. Math. Rice Univ. Houston TX USA

Data produced by a reproducible source contains redundant information which allows seismic inversion to simultaneously determine the high-frequency fluctuation in the P-wave velocity (or reflectivity) as well as the input energy source, The seismogram model is the plane-wave convolutional model derived from the constant density, variable sound velocity acoustic wave equation. The first step is to analyse this linearized model when the background velocity is constant. Then perturbations in the seismic data stably determine corresponding perturbations in the source and reflectivity. The stability of this determination improves as the slowness aperture over which the data is defined increases. Further, the normal operator for the convolutional seismogram model is continuous with respect to velocity. Thus the stability result for constant background velocities may be extended to more realistic background velocity models which vary slowly and smoothly with depth. The theory above is illustrated with four synthetic numerical examples derived from marine data. The examples indicate that for a wide slowness aperture, inversion is very effective in establishing the true shape of the reflectivity and the shape and location of the compactly supported energy source. As this aperture window narrows, the corresponding inversion-estimated model still describes the data quite accurately, but the inversion is not able to recover the original two distinct parameters.

关键词： Environmental and Earth science

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THE DUAL REGULARIZATION APPROACH TO SEISMIC VELOCITY INVERSION

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INVERSE PROBLEMS 1995年第3期11卷 501-531页

作者： GOCKENBACH, MS SYMES, WW TAPIA, RA Dept. of Comput. & Appl. Math. Rice Univ. Houston TX USA

Differential semblance optimization (DSO) is a novel way of approaching a class of inverse problems arising in exploration seismology. The promising feature of the DSO method is that it replaces a non-smooth highly non-convex cost function (the output least-squares (OLS) objective function) with a smooth cost function that is amenable to standard (local) optimization algorithms. The OLS problem can be written abstractly as a partially linear least-squares problem with linear constraints. The DSO objective function is derived from the associated quadratic penalty function. One way to view the DSO objective function is as a regularization of a function that is dual (in a certain sense) to the OLS objective function. Under suitable assumptions, the DSO method defines a parametrized path of minimizers converging to the desired solution and that, for certain values of the parameter, standard optimization techniques can be used to find a point on the path. The results of the theory are illustrated in the plane wave detection problem, a simple model problem for veracity inversion.

关键词： Instrumentation and measurement Environmental and Earth science

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Deterministic control of uncertain systems

Deterministic control of uncertain systems

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IEE Colloquium on Real Control Problems - No Solutions Yet?

作者： A. Zinober Dept. of Appl. & Comput. Math. Sheffield Univ. UK

In direct contrast to adaptive controllers the deterministic control of uncertain time-varying systems control is achieved using fixed nonlinear feedback control functions, which operate effectively over a specified magnitude range of a class of system parameter variations. There is no requirement for online identification of the values of the system parameters. Furthermore no statistical information of the system variations is required to yield the desired robust dynamic behaviour. If the parameter variations satisfy certain matching conditions, complete insensitivity to system variations can be achieved. The two main approaches, variable structure control (VSC) and Lyapunov control, are described.< >

关键词： Feedback Lyapunov methods Nonlinear systems Time-varying systems Variable structure systems

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Suppression of dispersion in NRZ communication systems using dispersion management

Suppression of dispersion in NRZ communication systems using...

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Conference on Lasers and Electro-Optics (CLEO)

作者： J.N. Kutz J.C. Bronski Princeton University Princeton NJ US Program in Appl. & Comput. Math. Princeton Univ. NJ USA

ISBN: (纸本)1557524432

Summary form only given. In recent years, much attention has been given to wavelength-division multiplexed (WDM) systems due to their ability to maximize lightwave communications. In practice, the combined effects of linear dispersion and nonlinear self phase modulation impose severe limitations on the long-haul performance of non-return-to-zero (NRZ) systems. The aim of this presentation is to provide an analytic description of the nonlinear pulse evolution in a NRZ communications system under a dispersion-management scheme.

关键词： Optical signal processing Dispersion Optical pulses math.matics Optical propagation Nonlinear equations Wavelength division multiplexing Phase modulation Scalability Solitons

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Object-orientation in software engineering education. Integrating concepts, methodology development models, and CASE in the curriculum

Object-orientation in software engineering education. Integr...

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International Conference on Software Engineering: Education and Practice

作者： G.R. Lowry Dept. of Appl. Comput. & Math. Tasmania Univ. Launceston Tas. Australia

Outlines a strategy for integrating object orientation in a curriculum which must also include structured methods (SM). Proceeding from familiar SM concepts, students rapidly grasp object orientation when OO concept evolution is traced to SM antecedents. Students are helped to distinguish OO approaches through the comparison of unique sequences of procedural steps which comprise methodology-derived development models (MDMs). When OO analysis, design and development are supported by CASE, the software must reify an MDM which is consistent with a familiar software life-cycle. comput.r-based tutorials are needed to support student work with CASE. A generic set of OO concepts, derived from an exhaustive study of OO methodologies, is identified. Summary definitions and page references are provided to help students to locate and compare the actual words of the methodologists, enriching their conceptual understanding. Comparative MDMs are illustrated. The paper concludes with recommendations for CASE tutorial development.

关键词： Software engineering comput.r aided software engineering Samarium Software development management Object oriented modeling math.matical model math.matics Engineering management Instruments Art

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Methodology for GPS Synchronization Evaluation with High Accuracy

Methodology for GPS Synchronization Evaluation with High Acc...

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IEEE Vehicular Technology Conference

作者： Zan Li Torsten Braun Desislava C. Dimitrova Inst. of Comput. Sci. & Appl. Math. Univ. of Bern Bern Switzerland

ISBN: (纸本)9781479980895

Clock synchronization in the order of nanoseconds is one of the critical factors for time-based localization. Currently used time synchronization methods are developed for the more relaxed needs of network operation. Their usability for positioning should be carefully evaluated. In this paper, we are particularly interested in GPS-based time synchronization. To judge its usability for localization we need a method that can evaluate the achieved time synchronization with nanosecond accuracy. Our method to evaluate the synchronization accuracy is inspired by signal processing algorithms and relies on fine-grain time information. The method is able to calculate the clock offset and skew between devices with nanosecond accuracy in real time. It was implemented using software defined radio technology. We demonstrate that GPS-based synchronization suffers from remaining clock offset in the range of a few hundred of nanoseconds but the clock skew is negligible. Finally, we determine a corresponding lower bound on the expected positioning error.

关键词： clock skew clock recovery Network operations Signal processing algorithms NANOSECOND Skew key factors

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Intrinsic noise induced state transition in coupled positive and negative feedback genetic circuit

Intrinsic noise induced state transition in coupled positive...

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5th IEEE International Conference on Systems Biology, ISB 2011

作者： Wang, Pei Lü, Jinhu Zhang, Yuhuan Ogorzalek, Maciej J. Sch. Math. Stat. Wuhan University Wuhan 430072 China Acad. Math. Syst. Sci. Chinese Academy of Sciences Beijing 100190 China Sch. Math. Sci. Capital Normal University Beijing 100048 China Fac. Phys. Astron. Appl. Comput. Sci. Jagiellonian University Krakow 30-059 Poland

ISBN: (纸本)9781457716669

It is well known that gene regulatory circuits can be modeled by the deterministic or stochastic approach. In this paper, a three-component coupled positive and negative feedback genetic circuit is firstly modeled deterministically by Hill kinetics. Then, a corresponding stochastic model is also investigated by using Gellispie's stochastic simulation. Some typical dynamical behaviors of the genetic circuit are further discussed based on the bifurcation analysis of deterministic system, including monostability, bistability, excitability, and oscillation. This paper aims to further investigate the effect of intrinsic noise inherently in stochastic models on steady states transition. It includes: i) For the parameters in deterministically bistable region, intrinsic noise may induce bistable switch for the not too large system volume, which can be observed by the generation of a new stable steady state;ii) For the parameters in deterministically excitable region, intrinsic noise may induce periodic switch for the very large system volume, which can be observed by the stabilization of another unstable steady state and the switching between two stable states;iii) When time delays are introduced in these two models, similar phenomena can be observed. The above results will certainly increase the understanding of the inner relationships between different modeling for the genetic circuit. It sheds some light on the real- world engineering appl.cations, such as the engineering design of synthetic circuits. © 2011 IEEE.

关键词： Feedback

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Activity level of a neural net and its learning environment

Activity level of a neural net and its learning environment

引用

International Joint Conference on Neural Networks (IJCNN)

作者： K. Liu J.E. Jones Y. Chen Dept. of Appl. Math. & Comput. Sci. Colorado Sch. of Mines Golden CO USA

Summary form only given, as follows. When a neural net is used to solve continuous problems, the learning environment, which may influence convergence and accuracy, differs from that for true-false problems. Based on the energy model for a neural net, different activity levels of the net are generalized to learn one selected continuous problem-polynomial function. The training results showed that there are some optimal activity levels that lead the net to obtain better accuracy than that from other levels. The concepts of maximum energy and minimum energy (or 'thermal noise') are proposed to explain why it is possible for a net to achieve a good learning environment to fit to the continuous problems.< >

关键词： Neural networks Artificial neural networks Learning Artificial intelligence Educational institutions Convergence Polynomials Working environment noise

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EEG source reconstruction performance as a function of skull conductance contrast

EEG source reconstruction performance as a function of skull...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： S. T. Hansen L. K. Hansen Dept. of Appl. Math. & Comput. Sci. Tech. Univ. of Denmark Lyngby Denmark

ISBN: (纸本)9781467369985

Through simulated EEG we investigate the effect of the forward model's appl.ed skull:scalp conductivity ratio on the source reconstruction performance. We show that having a higher conductivity ratio generally leads to improvement of the solution. Additionally we see a clear connection between higher conductivity ratios and lower coherence, thus a reduction of the ill-posedness of the EEG inverse problem. Finally we show on real EEG data the stability of the strongest source recovered across conductivity ratios.

关键词： EEG source reconstruction Forward models Inverse problem Sparsity Variational approximation

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