Mohd Saberi Mohamad  Sigeru Omatu  Safaai Deris  Michifumi Yoshioka 《IEEJ Transactions on Electrical and Electronic Engineering》2009,4(6):725-730

Gene expression data produced by microarray machines are useful for cancer classification. However, the process of gene selection for the classification faces a major problem because of the properties of the data such as the small number of samples compared with the huge number of genes (high-dimensional data), irrelevant genes, and noisy data. Hence, this paper proposes a three-stage method to select a small subset of informative genes which is most relevant for the cancer classification. It has three stages: (i) pre-selecting genes using a filter method to produce a subset of genes; (ii) optimizing the gene subset using a multi-objective hybrid method to yield near-optimal subsets of genes; (iii) analyzing the frequency of appearance of each gene in the different near-optimal gene subsets to produce a small (final) subset of informative genes. Five gene expression data sets are used to test the effectiveness of the proposed method. Experimental results show that the performance of the proposed method is superior to other experimental methods and related previous works. A list of informative genes in the final gene subset is also presented for biological usage. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.  相似文献   

    

Tao Yang  Anton A. Stoorvogel  Ali Saberi 《国际强度与非线性控制杂志
》2013,23(17):1899-1931

The main contribution of this paper is to completely characterize the dynamic behavior of the discrete‐time double integrator with a saturated locally stabilizing linear state feedback law. In continuous‐time setting, any linear state feedback control law that locally stabilizes the double integrator also globally stabilizes the system in the presence of actuator saturation. In discrete‐time setting, the equivalent of the double integrator does not have the same property. In this paper, we completely characterize the global behavior of saturated locally stabilizing linear state feedback laws for the discrete‐time double integrator. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

    

Sandip Roy  Yan Wan  Ali Saberi  Mengran Xue 《国际强度与非线性控制杂志
》2012,22(15):1691-1702

Motivated by both distributed computation and decentralized control applications, we studied the distributed linear iterative algorithms with memory. Specifically, we showed that the system of linear equations G x = b can be solved through a distributed linear iteration for arbitrary invertible G using only a single memory element at each processor. Further, we demonstrated that the memoried distributed algorithm can be designed to achieve much faster convergence than a memoryless distributed algorithm. Two small simulation examples were included to illustrate the results. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

    

Xu Wang  Ali Saberi  Anton A. Stoorvogel  Håvard Fjær Grip 《国际强度与非线性控制杂志
》2012,22(14):1562-1570

In this paper, we study control of a chain of integrators under actuator saturation and non‐additive disturbances. We shall show that boundedness of the states can be ensured if the disturbances are matched and integral‐bounded, misaligned and magnitude‐bounded, or a combination of the two, using either a static or a dynamic low‐gain state feedback. This result is an extension of our earlier work on double integrator. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

    

Xu Wang  Anton A. Stoorvogel  Ali Saberi  Peddapullaiah Sannuti 《国际强度与非线性控制杂志
》2012,22(7):743-762

  相似文献   

    

Sandip Roy  Ali Saberi  Yan Wan 《国际强度与非线性控制杂志
》2010,20(11):1299-1305

We develop a control methodology for linear time‐invariant plants that uses multiple delayed observations in feedback. Using the special coordinate basis, we show that multiple‐delay controllers can always be designed to stabilize minimum‐phase plants, and identify a class of non‐minimum‐phase plants that can be stabilized using these controllers. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

    

Xu Wang  Ali Saberi  Anton A. Stoorvogel  Sandip Roy  Peddapullaiah Sannuti 《国际强度与非线性控制杂志
》2010,20(11):1234-1254

This paper investigates time‐invariant linear systems subject to input and state constraints. We study discrete‐time systems with full or partial constraints on both input and state. It has been shown earlier that the solvability conditions of stabilization problems are closely related to important concepts such as the right invertibility or non‐right invertibility of the constraints, the location of constraint invariant zeros, and the order of constraint infinite zeros. In this paper, for general time‐invariant linear systems with non‐right invertible constraints, necessary and sufficient conditions are developed under which semi‐global stabilization in the admissible set can be achieved by state feedback. Sufficient conditions are also developed for such a stabilization in the case where measurement feedback is used. Such sufficient conditions are almost necessary. Controllers for both state feedback and measurement feedback are constructed as well. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

    

Rahul Dhal  Sandip Roy  Yan Wan  Ali Saberi 《International journal of control》2013,86(12):2604-2614

We develop majorisation results that characterise changes in eigenvector components of a graph's adjacency matrix when its topology is changed. Specifically, for general (weighted, directed) graphs, we characterise changes in dominant eigenvector components for single- and multi-row incrementations. We also show that topology changes can be tailored to set ratios between the components of the dominant eigenvector. For more limited graph classes (specifically, undirected, and reversibly-structured ones), majorisations for components of the subdominant and other eigenvectors upon graph modifications are also obtained.  相似文献   

    

Xu Wang  Ali Saberi  Anton A. Stoorvogel  Sandip Roy  Peddapullaiah Sannuti 《International journal of control》2013,86(10):1870-1881

This article considers discrete-time linear time-invariant systems subject to input and state constraints. It is shown that in the recoverable region (which is the largest domain of attraction that is theoretically achievable) system can be semi-globally stabilised by nonlinear feedbacks while satisfying the constraints. Moreover, the recoverable region for the given system is constructed by constructing the same, however, for a reduced-order subsystem of the given system. Such a reduction in the order or dimension of the system generally leads to a considerable simplification in the computational effort.  相似文献   

    

Nastaran Saberi  Richard Kelly  Margot Flemming  Qinghuan Li 《International journal of remote sensing》2013,34(3):996-1018

ABSTRACT

The physical properties of a snowpack strongly influence the emissions from the substratum, making snow property retrievals feasible by means of the surface brightness temperature observed by passive microwave sensors. Depending on the spatial resolution observed, time series records of daily snow coverage and critical snowpack properties such as snow depth (SD) and snow water equivalent (SWE) could be helpful in applications ranging from modelling snow variations for water resources management in a catchment to global climatologic studies. However, the challenge of including spaceborne SWE products in operational hydrological and hydroclimate modelling applications is very demanding with limited uptake by these systems, mostly attributed to insufficient SWE estimation accuracy. The root causes of this challenge include the coarse spatial resolution of passive microwave (PM) observations that observe highly aggregated snowpack properties at the spaceborne scale, and inadequacies during the retrieval process caused by uncertainties with the forward emission modelling of snow and challenges to find robust parameterizations of the models. While the spatial resolution problem is largely in the realm of engineering design and constrained by physical restrictions, a better understanding of developed and adopted retrieval methodologies can provide the clarity needed to enhance our knowledge in this field. In this paper, we review snow depth and SWE retrieval methods using PM observations, taking only dry snow retrieval processes into consideration. Snow properties using PM observations can be modelled by purely empirical relations based on underlying physical processes, and SD and SWE can be estimated by regression-based approaches. Snow property retrievals have been refined gradually throughout four decades use of PM observations in tandem with better understanding of physical processes, inclusion of better snowpack parameterizations, improved uncertainty analysis frameworks, and applying better inversion algorithms. Studying available methods, we conclude that snowpack parameterization is key to accurate retrieval. By improving retrieval algorithm architectures to better capture dynamic snowpack evolution processes, SWE estimates are likely to improve. We conclude that this challenge can be addressed by coupling emission models and land surface models or integrating weather-driven snowpack evolution into emission models and performing inversion in a Bayesian framework.  相似文献