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New algorithm to find a shape of a finite set of points

- Sukhorukova, Nadezda, Ugon, Julien

Queueing programming models in telecommunication network maintenance

- Ugon, Julien, Jia, Long, Ouveysi, Iradj

A feature selection approach for unsupervised classification based on clustering

- Rubinov, Alex, Soukhoroukova, Nadejda, Ugon, Julien

  • Authors: Rubinov, Alex , Soukhoroukova, Nadejda , Ugon, Julien
  • Date: 2004
  • Type: Text , Conference paper
  • Relation: Paper presented at Sixth International Conference on Optimization: Techniques and Applications (ICOTA) , University of Ballarat, Ballarat, Victoria : 9th-11th December 2004
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  • Description: Data have been collected for many years in different scientific (industrial, medical) research groups. Very often these groups kept all the the they could collect. It is possible that the data contains a lot of noisy features which do not bring any information, but make the problem more complicated. The additional study of eliminating non-informative and selecting informative features is very important in the area of Data Mining. There are several feature selection methods which were developed for supervised classification. The area of feature selection for unsupervised classification is not so developed. In this paper we present a new feature selection approach for unsupervised classification, based on clustering and nonsmooth optimisation techniques.
  • Description: 2003004085

Optimization in wireless local area network

- Kouhbor, Shahnaz, Ugon, Julien, Kruger, Alexander, Rubinov, Alex, Branch, Philip

Solving Euclidian travelling salesman problem using discrete-gradient based clustering and kohonen neural network

- Ghosh, Moumita, Ugon, Julien, Ghosh, Ranadhir, Bagirov, Adil

A new algorithm for the placement of WLAN access point based on nonsmooth optimization technique

- Kouhbor, Shahnaz, Ugon, Julien, Kruger, Alexander, Rubinov, Alex, Branch, Philip

  • Authors: Kouhbor, Shahnaz , Ugon, Julien , Kruger, Alexander , Rubinov, Alex , Branch, Philip
  • Date: 2005
  • Type: Text , Conference paper
  • Relation: Paper presented at the 7th International Conference on Advanced Communication Technology, Phoenix Park, Korea : 21st February, 2005
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  • Description: In wireless local area network (WLAN), signal coverage is obtained by proper placement of access points (APs). The impact of incorrect placement of APs is significant. If they are placed too far apart, they generate a coverage gap but if they are too close to each other, this leads to excessive co-channel interferences. In this paper, we describe a mathematical model we have developed to find the optimal number and location of APs. To solve the problem, we use an optimization algorithm developed at the University of Ballarat called discrete gradient algorithm. Results indicate that our model is able to solve optimal coverage problems for different numbers of users.
  • Description: E1
  • Description: 2003001376

An algorithm for minimizing clustering functions

- Bagirov, Adil, Ugon, Julien

  • Authors: Bagirov, Adil , Ugon, Julien
  • Date: 2005
  • Type: Text , Journal article
  • Relation: Optimization Vol. 54, no. 4-5 (Aug-Oct 2005), p. 351-368
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  • Description: The problem of cluster analysis is formulated as a problem of nonsmooth, nonconvex optimization. An algorithm for solving the latter optimization problem is developed which allows one to significantly reduce the computational efforts. This algorithm is based on the so-called discrete gradient method. Results of numerical experiments are presented which demonstrate the effectiveness of the proposed algorithm.
  • Description: C1
  • Description: 2003001266

Application of nonsmooth optimisation to data analysis

- Ugon, Julien

  • Authors: Ugon, Julien
  • Date: 2005
  • Type: Text , Thesis , PhD
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  • Description: The research presented in this thesis is two-fold: on the one hand, major data mining problems are reformulated as mathematical programming problems. These problems should be carefully designed, since from their formulation depends the efficiency, perhaps the existence, of the solvers. On the other hand, optimisation methods are adapted to solve these problems, most of which are nonsmooth and nonconvex. This part is delicate, as the solution is often required to be good and obtained fast. Numerical experiments on real-world datasets are presented and analysed.
  • Description: Doctor of Philosophy

Minimization of the sum of minima of convex functions and its application to clustering

- Rubinov, Alex, Soukhoroukova, Nadejda, Ugon, Julien

  • Authors: Rubinov, Alex , Soukhoroukova, Nadejda , Ugon, Julien
  • Date: 2005
  • Type: Text , Book chapter
  • Relation: Continuous Optimization Chapter p. 409-434
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  • Description: We study functions that can be represented as the sum of minima of convex functions. Minimization of such functions can be used for approximation of finite sets and their clustering. We suggest to use the local discrete gradient (DG) method [Bag99] and the hybrid method between the cutting angle method and the discrete gradient method (DG+CAM) [BRZ05b] for the minimization of these functions. We report and analyze the results of numerical experiments.
  • Description: 2003004082

Optimal placement of access point in WLAN based on a new algorithm

- Kouhbor, Shahnaz, Ugon, Julien, Kruger, Alexander, Rubinov, Alex

  • Authors: Kouhbor, Shahnaz , Ugon, Julien , Kruger, Alexander , Rubinov, Alex
  • Date: 2005
  • Type: Text , Conference paper
  • Relation: Paper presented at ICMB 2005, International Conference on Mobile Business, Sydney, Australia, 11-13 July 2005, Sydney : 11th - 13th July, 2005
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  • Description: When designing wireless communication systems, it is very important to know the optimum numbers and locations for the access points (APs). The impact of incorrect placement of APs is significant. If they are placed too far apart, they will generate a coverage gap, but if they are too close to each other, this will lead to excessive co-channel interferences. In this paper we describe a mathematical model developed to find the optimal number and location of APs. To solve the problem, we use the Discrete Gradient optimization algorithm developed at the University of Ballarat. Results indicate that our model is able to solve optimal coverage problems for different numbers of users.
  • Description: 2003001377

Optimisation solvers and problem formulations for solving a data clustering problem

- Ugon, Julien, Rubinov, Alex

Supervised data classification via max-min separability

- Ugon, Julien, Bagirov, Adil

Classes and clusters in data analysis

- Rubinov, Alex, Sukhorukova, Nadezda, Ugon, Julien

  • Authors: Rubinov, Alex , Sukhorukova, Nadezda , Ugon, Julien
  • Date: 2006
  • Type: Text , Journal article
  • Relation: European Journal of Operational Research Vol. 173, no. 3 (Sep 2006), p. 849-865
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  • Description: We discuss the relation between classes and clusters in datasets with given classes. We examine the distribution of classes within obtained clusters, using different clustering methods which are based on different techniques. We also study the structure of the obtained clusters. One of the main conclusions, obtained in this research is that the notion purity cannot be always used for evaluation of accuracy of clustering techniques. (c) 2005 Elsevier B.V. All rights reserved.
  • Description: C1
  • Description: 2003001593

Coverage in WLAN : Optimization model and algorithm

- Kouhbor, Shahnaz, Ugon, Julien, Mammadov, Musa, Rubinov, Alex, Kruger, Alexander

Coverage in WLAN with minimum number of access points

- Kouhbor, Shahnaz, Ugon, Julien, Rubinov, Alex, Kruger, Alexander, Mammadov, Musa

Piecewise partially separable functions and a derivative-free algorithm for large scale nonsmooth optimization

- Bagirov, Adil, Ugon, Julien

  • Authors: Bagirov, Adil , Ugon, Julien
  • Date: 2006
  • Type: Text , Journal article
  • Relation: Journal of Global Optimization Vol. 35, no. 2 (Jun 2006), p. 163-195
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  • Description: This paper introduces the notion of piecewise partially separable functions and studies their properties. We also consider some of many applications of these functions. Finally, we consider the problem of minimizing of piecewise partially separable functions and develop an algorithm for its solution. This algorithm exploits the structure of such functions. We present the results of preliminary numerical experiments.
  • Description: 2003001532

Facility location via continuous optimization with discontinuous objective functions

- Ugon, Julien, Kouhbor, Shahnaz, Mammadov, Musa, Rubinov, Alex, Kruger, Alexander

  • Authors: Ugon, Julien , Kouhbor, Shahnaz , Mammadov, Musa , Rubinov, Alex , Kruger, Alexander
  • Date: 2007
  • Type: Text , Journal article
  • Relation: ANZIAM Journal Vol. 48, no. 3 (2007), p. 315-325
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  • Description: Facility location problems are one of the most common applications of optimization methods. Continuous formulations are usually more accurate, but often result in complex problems that cannot be solved using traditional optimization methods. This paper examines the use of a global optimization method - AGOP - for solving location problems where the objective function is discontinuous. This approach is motivated by a real-world application in wireless networks design. © Australian Mathematical Society 2007.
  • Description: 2003004859

Implementation of novel methods of global and nonsmooth optimization : GANSO programming library

- Beliakov, Gleb, Ugon, Julien

  • Authors: Beliakov, Gleb , Ugon, Julien
  • Date: 2007
  • Type: Text , Journal article
  • Relation: Optimization Vol. 56, no. 5-6 (2007), p. 543-546
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  • Description: We discuss the implementation of a number of modern methods of global and nonsmooth continuous optimization, based on the ideas of Rubinov, in a programming library GANSO. GANSO implements the derivative-free bundle method, the extended cutting angle method, dynamical system-based optimization and their various combinations and heuristics. We outline the main ideas behind each method, and report on the interfacing with Matlab and Maple packages.
  • Description: C1
  • Description: 2003004865

Optimization solvers and problem formulations for solving data clustering problems

- Ugon, Julien

  • Authors: Ugon, Julien
  • Date: 2007
  • Type: Text , Journal article
  • Relation: Pacific Journal of Optimization Vol. 3, no. 2 (2007), p. 387-397
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  • Description: A popular apprach for solving complex optimization problems is through relaxation: some constraints are removed in order to have a convex problem approximating the original problem. On the other hand, direct approaches for solving such problems are becoming increasingly powerful. This paper examines two cases drawn from data analysis, in order to compare the two techniques.
  • Description: C1
  • Description: 2003004937

Optimisation of operations of a water distribution system for reduced power usage

- Bagirov, Adil, Ugon, Julien, Barton, Andrew, Briggs, Steven

  • Authors: Bagirov, Adil , Ugon, Julien , Barton, Andrew , Briggs, Steven
  • Date: 2008
  • Type: Text , Conference paper
  • Relation: Paper presented at 9th National Conference on Hydraulics in Water Engineering: Hydraulics 2008, Darwin, Northern Territory : 22nd-26th September 2008
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  • Description: There are many improvements to operation that can be made to a water distribution system once it has been constructed and placed in ground. Pipes and associated storages and pumps are typically designed to meet average peak daily demands, offer some capacity for growth, and also allow for some deterioration of performance over time. However, the 'as constructed' performance of the pipeline is invariably different to what was designed on paper, and this is particularly so for anything other than design flows, such as during times of water restrictions when there are significantly reduced flows. Because of this, there remain significant benefits to owners and operators for the adaptive and global optimisation of such systems. The present paper uses the Ouyen subsystem of the Northern Mallee Pipeline, in Victoria, as a case study for the development of an optimisation model. This has been done with the intent of using this model to reduce costs and provide better service to customers on this system. The Ouyen subsystem consists of 1600 km of trunk and distribution pipeline servicing an area of 456,000 Ha. The system includes 2 fixed speed pumps diverting water from the Murray River at Liparoo into two 150 ML balancing storages at Ouyen, 4 variable speed pumps feeding water from the balancing storages into the pipeline system, 2 variable speed pressure booster pumps and 5 town balancing storages. When considering all these components of the system, power consumption becomes an important part of the overall operation. The present paper considers a global optimisation model to minimise power consumption while maintaining reasonable performance of the system. The main components of the model are described including the network structure and the costs functions associated with the system. The final model presents the cost functions associated with the pump scheduling, including the penalties descriptions associated with maintaining appropriate storages levels and pressure bounds within the water distribution network.
  • Description: 2003006758