INSTITUT SAINS MATEMATIK UNIVERSITI MALAYA SIRI … · SIRI SEMINAR KUMPULAN PENYELIDIKAN ... While...

INSTITUT SAINS MATEMATIK

UNIVERSITI MALAYA

SIRI SEMINAR KUMPULAN PENYELIDIKAN

Bil:3/2014

Title : Towards a unifying approach for optimal inventory policies in finite planning horizon

Speaker : Lakdere Benkherouf (Kuwait University) Date : 15 January 2014 (Wednesday) Time : 3.00 pm – 4.00 pm Venue : MM3, Institute of Mathematical Sciences

Abstract

Benkherouf and Gilding (2009) (SIAM Journal of Control and Optimization) suggested a procedure for finding an optimal replenishment schedule for Economic Lot Size Models in Finite horizon. The procedure turns out to be applicable to a large class of inventory models far beyond its original motivation. This talk will go through a number of these applications and conclude with a simple tutorial on the procedure

Everyone is welcome


UNIVERSITI MALAYA


Bil:04/2014

Title : Rydberg transitions for positron–hydrogen collisions (scaling law for cross section)

Speaker : Dr. Arijit Ghoshal Department of Mathematics, Burdwan University, India Date : 14 March 2014 (Friday) Time : 10.00 am – 11.00 am Venue : MM3, Institute of Mathematical Sciences

Abstract

The collision dynamics of excitations of hydrogen atom in arbitrary nlm-states by positron impact has been investigated using a distorted-wave model in the momentum space. It has been possible to obtain the distorted-wave scattering amplitude in a closed analytical form. A detailed study has been made on the differential and total cross sections in the energy range 20–300 eV of incident positron. Furthermore, a simple law has been derived for obtaining asymptotic cross sections for excitation into different angular momentum states.

Everyone is welcome

Bil:05/2014


UNIVERSITI MALAYA


Title : An Augmentation Theorem for Vertex-disjoint Triangle Sets

Speaker : Prof. Zan-Bo Zhang Department of Computer Engineering, Guangdong Industry Technical College, Guangzhou, 510300, China

Date : 16 April 2014 (Wednesday) Time : 3:00 pm – 4:00 pm Venue : MM3, Institute of Mathematical Sciences

Abstract

Vertex-disjoint triangle sets (triangle sets for short) have been studied extensively. Many theoretical and computational results have been obtained. While the maximum triangle set problem can be viewed as the generalization of the maximum matching problem, there seems no parallel result to Berge’s augmenting path characterization on maximum matching [C. Berge. Two theorems in graph theory. Proc. Nat. Acad. Sci. U.S.A. 43 (1957), 842-844.]. In this talk, we describe a class of structures called triangle string, which is equivalent to the class of union of two triangle sets in a graph. Based on the concept of triangle strings, a sufficient and necessary condition that a triangle set can be augmented is given. We develop an algorithm to test whether a graph G with maximum degree 4 is a triangle string, and if G is a triangle string, compute a maximum triangle

set of it. Finally, a sufficient and necessary condition for a triangle string to have a triangle factor is showed.

Research Group: Discrete Mathematics Research Group

INSTITUTE OF MATHEMATICAL SCIENCES

UNIVERSITY OF MALAYA


Bil:06/2014

Title : Genetic Network Modelings and Differential Equations Speaker : Prof. Dr. P. BALASUBRAMANIAM Professor Department of Mathematics Gandhigram Rural Institute-Deemed University Gandhigram-624302 Tamilnadu, INDIA Date : 21 – 05 – 2014 (Wednesday) Time : 3.00 PM – 4.00 PM Venue : MM3, Institute of Mathematical Sciences

Abstract

In this presentation to describe Genetic Regularity Systems, in particular

ordinary, partial differential equations, stochastic equations and

qualitative differential equations fomalisms are going to be discussed.

Linear control theory for gene network modeling and Boolean control

networks for optimal control problem could be demonstrated for

applications.

Everyone is welcome




Bil:07/2014

Title: The Optimal Manufacturing Batch Size with Rework under Time-Varying Demand Process for a Finite Time Horizon.

Speaker: Sarah Bt Hj Musa ( SGP 100005) Date: 28 – 05 – 2014 (Wednesday) Time: 3.00 PM – 4.00 PM Venue: MM3, Institute of Mathematical Sciences

Abstract

Rework is one of the main issues in reverse logistic and green supply chain, since it can reduce

production cost and environmental problem. Many researchers focus on developing rework model,

but to the knowledge of the author, none of them developed model for time-varying demand rate. In

this study, we extend previous work and develop multiple batch production system for time-varying

demand rate with rework. In this model, at the first stage, all items of a batch are manufactured and

produced good quality items until the manufacturing facility may deteriorate and became out of

control. Thus, it begins to produce defective items. These defective items will be reworked under

two different rework processes with several policies. Numerical illustration and analysis are shown

to see the effectiveness of the proposed models.

Everyone is welcome




Bil:08/2014

Title : Modeling the occurrence and amount of Malaysia rainfall Speaker : Dr. Rossita M. Yunus Institute of Mathematical Sciences, University of Malaya Date : 11 – 06 – 2014 (Wednesday) Time : 3.00 PM – 4.00 PM Venue : MM3, Institute of Mathematical Sciences

Abstract

Modeling the distribution of rainfall data is important to predict

characteristics of rainfall pattern. The Tweedie distribution models two

important features of rainfall: the occurrence and amount, complements

the studies that use two separate distributions to model the rainfall data.

In the study, the Tweedie distributions (e.g. Poisson gamma and gamma)

are used for modeling daily and monthly rainfall data with a set of

predictors, for four stations in Peninsular Malaysia from 1983 to 2012.

First, models with only sine and cosine terms (base model) are fitted to

model the harmonic pattern of rainfall, and then one climatologically

variable is added in addition to the base model. Climatologically variables

have shown significant impacts on the amount of rainfall of the studies

stations.

Everyone is welcome




Bil:09/2014

Title : Statistical Shape Models for some Dental Applications Speaker : Norli Anida Abdullah (SHB090010) Institute of Mathematical Sciences, University of Malaya Date : 25 – 06 – 2014 (Wednesday) Time : 3.00 PM – 4.00 PM Venue : MM3, Institute of Mathematical Sciences

Abstract

Two statistical shape models of the dental arch; the multivariate normal (MVN)

and multivariate complex normal (MVCN) shape models are used to guide in the

design of stock impression trays and predicting the natural teeth positions for

rehabilitating edentulous patients. A shape feature represented by distances and

angles of selected teeth on fully dentate arches was first proposed from the

digital images of the dental arch as shape feature and its properties, shape

category and probability distributions were explored. Three categories of MVN

shape models with variation from the means were established. Knowledge of this

shape models was used to design three prototype impression trays for dentate

patients with and without missing teeth. A more precise shape feature using the

Fourier descriptors and its probability distribution was further proposed to be

used with edentulous patients. Anatomical landmarks on edentulous arches

were linked to the MVCN shape models and a guide for predicting the natural

teeth positions was proposed and verified to assist clinicians in positioning

artificial teeth on complete dentures. In the 80% of the casts studied, the MVCN

shape models may be used with anatomical landmarks to predict the natural

teeth positions with an average error of 0.95 mm for each tooth.

Everyone is welcome




Bil:10/2014

Title : Stochastic and Nonlinear Models Speaker : Prof. Dr. Subir Das

Department of Mathematical Sciences, Indian Institute of Technology (Banaras Hindu University), INDIA Date : 30 – 06 – 2014 (Monday) Time : 10.00 AM – 11.00 AM Venue : MM3, Institute of Mathematical Sciences

Abstract

In the first part of the lecture the details of homotopy analysis method will be discussed to obtain approximate analytic solutions of the time-fractional diffusion-wave equation with given initial conditions. The effect of reaction term with long term correlation to the diffusion-wave solutions for various values of anomalous exponent to constitute a good mathematical model will be discussed in detail for various engineering and scientific systems. Effects of parameters on the solution profile will be presented through graphs for different particular cases. Sub-diffusion and super-diffusion phenomena for birth and death processes will also be shown trough figures.

In the second part of the lecture the function projective synchronization between different fractional order chaotic systems with uncertain parameters using modified adaptive control method will be shown. The adaptive function projective synchronization controller and identification parameter laws are developed on the basis of Lyapunov stability theory. The method is successfully applied for the function projective synchronization between some fractional order chaotic systems. The analysis of the synchronization time with variations of fractional order derivatives is the key feature of the content. The numerical simulation results clearly show that the modified method is very much efficient and reliable for synchronizing the two different fractional order chaotic systems

Everyone is welcome

Bil:11/2014




Title : Pseudo parallel CR submanifolds in non-flat complex spaces forms

Speaker : Loo Tee How Institute of Mathematical Sciences, University of Malaya

Date : 02- 07- 2014 (Wednesday) Time : 3:00 pm – 4:00 pm Venue : MM3, Institute of Mathematical Sciences

Abstract

We classify pseudo parallel proper CR submanifolds in non-flat complex space

forms with CR dimension greater than one. With this result, the non-existence of recurrent

as well as semi parallel proper CR submanifolds in non-flat complex space forms with CR

dimension greater than one can also be obtained.

Everyone is welcome

Bil:12/2014




Title : Hierarchical Production Planning and Scheduling: A Fuzzy Programming Approach

Speaker : Muzalna Mohd Jusoh (SHB100015) Institute of Mathematical Sciences, University of Malaya

Date : 16- 07- 2014 (Wednesday) Time : 3:00 pm – 4:00 pm Venue : MM3, Institute of Mathematical Sciences

Abstract

Production planning and scheduling is a complicated task which involve multiple functional units in an

organization to develop an efficient decision plan for upcoming period, in which the parameters like market

demand, available resources and related operating costs are not known precisely, that is to say uncertain or

fuzzy. This research considers the hierarchical concept to solve a production planning problem in the process

industry in a fuzzy environment. The basic idea of applying the hierarchical approach is to reduce the

problem’s complexity by the decomposition of the planning process into isolated sub-problems which may

then be solved using appropriate models. In this study, the proposed fuzzy hierarchical production planning

model consists of decision making at two levels. A fuzzy aggregate production planning (FAPP) model is

developed in the first level, and then a fuzzy disaggregate production planning (FDPP) model is developed at

the second level. In order to validate the quality of the proposed model, the fuzzy mathematical programming

approach that combines the concept of fuzzy and possibilistic programming was employed to solve both FAPP

and FDPP models. The model’s performances were evaluated by comparing its results with a previously

reported approach. In addition, the author conducted a robustness testing methodology at varying demand

forecast errors for both models. The findings concluded that the fuzzy programming approach could improve

the solution of production planning problems under fuzzy environment. The most important point to highlight is

the fact that a significant cost savings has been achieved when using the fuzzy mixed integer linear

programming to solve the fuzzy hierarchical production planning problem compared with the deterministic

model.

Everyone is welcome

Bil:13/2014




Title : Numerical procedures for outlier detection in circular time series models

Speaker : Ibrahim bin Mohamed Institute of Mathematical Sciences, University of Malaya

Date : 23 - 07- 2014 (Wednesday) Time : 3:00 pm – 4:00 pm Venue : MM3, Institute of Mathematical Sciences

Abstract

It is known that the occurrence of outliers in linear or non-linear time series models

may have adverse effects on the modeling of the data. Consequently, extensive research

has been conducted on developing outlier detection procedures so that outliers can be

properly managed. However, no work has been done on the problem of outliers in circular

time series data. We intend to develop a numerical procedure for detecting these outliers

in circular time series data. A number of circular time series models have been proposed

including the circular autoregressive model. We extend the iterative outlier detection

procedure which has been successfully used in linear time series models to the circular

autoregressive model. The proposed procedure shows a good performance when

investigated via simulation for the circular autoregressive model of order one. For

illustration, we apply the procedures to a particular set of wind direction data. These

procedures could be very useful in improving the modelling and inferential processes for

circular time series data.

Everyone is welcome

Bil:14/2014




Title : Geometric means for positive definite matrices and its generalization Speaker : Professor Dr. Tin-Yau Tam Chair and Lloyd and Sandra Nix Professor in Mathematics Department of Mathematics and Statistics Auburn University, USA. Date : 1 August 2014 (Friday) Time : 10:00 am – 11:00 am Venue : DKM4, Institute of Mathematical Sciences

Abstract

We discuss some results of Ando, Bhatia, Hiai and others that involve

geometric means of two positive definite matrices A and B. The geometric means

lies on the geodesic joining A and B. We then consider their extensions in the

context of symmetric space of the noncompact type. Some partial order relation is

given.

Everyone is welcome

Bil:15/2014




Title : Preservers of Upper Ideals of Matrices: Tournaments; Primitivity Speaker : Professor Dr. LeRoy B. Beasley Department of Mathematics and Statistics Utah State University, USA. Date : 1 August 2014 (Friday) Time : 11:00 am – 12:00 pm Venue : DKM4, Institute of Mathematical Sciences

Abstract

Let M denote the set of matrices over some semiring. An upper ideal of

matrices in M is a set U such that if A U and B is any matrix in ,M then

.U BA We investigate linear operators T that strongly preserve certain upper

ideals (that is, linear operators on M with the property that UX if and only if

U)(XT ). We then characterize linear operators that strongly preserve sets of

tournament matrices and sets of primitive matrices. Specifically, we show that if T strongly preserves the set of regular tournaments when n is odd or nearly regular

tournaments when n is even, then for some permutation matrix, ,P XPPXT t)(

for all matrices X with zero main diagonal, or PXPXT tt)( for all matrices X

with zero main diagonal. Similar results are shown for linear operators that

strongly preserve the set of primitive matrices whose exponent is k for some

values of k , and for those that strongly preserve the set of nearly reducible

primitive matrices.

Everyone is welcome




Bil:17/2014

Title : Closeness of Hidden Truncation and Additive Component based Skewed Distributions- an Empirical Assessment Speaker : Professor Subrata Chakraborty

Department of Statistics, Dibrugarh University, Dibrugarh - 786004, India

Date : 6 August 2014 (Wednesday) Time : 3.00 PM – 4.00 PM Venue : MM3, Institute of Mathematical Sciences

Abstract

Hidden truncation (HT) and additive component (AC) are two well known

paradigms of generating skewed distributions from known symmetric distribution. In Case

of normal distribution it has been known that both the above paradigms lead directly to

Azzalini’s (1985) skew normal distribution. While the HT directly gives the Azzalini’s (1985)

skew normal distribution, the one generated by AC also leads to the same distribution

under a re-parameterization proposed by Arnold and Gomez (2009). Arnold and Gomez

(2009) used the same re-parameterization with Logistic and Laplace distribution and have

graphically shown that the pdfs generated by the HT and the AC method do show some

closeness, but they do not coincide as in the case of normal distribution. In this paper, an

attempt has been made to investigate numerically as well as statistically the closeness of

skew distributions generated by HT and AC methods under the same re-parameterization

of Arnold and Gomez (2009) in the case of logistic and Laplace distributions.

Keywords and Phrases: Skew logistic distribution, Skew Laplace distribution, Kullback–

Leibler (KL) distance, Simulation, KS test, Monte Carlo integration.

Everyone is welcome




Bil:18/2014

Title : Recent Developments in Recursive Estimation for Time Series Models Speaker : Professor A. Thavaneswaran Date : 20 August 2014 (Wednesday) Time : 3.00 PM – 4.00 PM Venue : MM3, Institute of Mathematical Sciences

Abstract

Recently there has been a growing interest in joint estimation of the location and scale

parameters using combined estimation functions, for models with finite variance and with

infinite variance (Thavaneswaran et al. (2013(a))). Martingale estimating function method

provides a convenient framework for studying inference for nonlinear time series models

Thavaneswaran and Abraham (1988). Moreover, when the first two conditional moments

are functions the same parameter and the information about the higher order conditional

moments of the observed process become available combined estimating functions are

more informative than the component estimating functions (see Thavaneswaran et al.

(2013(b))). In this paper, first a theorem on recursive estimation is extended to

multiparameter setup and it is shown that the unified approach can be used to estimate

the location parameter recursively for models with finite variance/infinite variance. The

method is applied for the joint recursive estimation of the location and scale parameters

for regression model with ARCH errors, RCA model with GARCH models and generalized

ACD models.

Everyone is welcome




Title : Middle-Censoring

Speaker : Prof. Sreenivasa Rao Jammalamadaka

Department of Statistics and Applied Probability,

University of California, Santa Barbara, USA

Date : 17 – 09 – 2014 (Wednesday)

Time : 3.00 PM – 4.00 PM

Venue : MM3, Institute of Mathematical Sciences

Abstract

In connection with survival analysis and related problem, there is considerable literature

which treats data that is censored from the left, the right or both. In this talk, we consider

situations where the data becomes unobservable if it falls inside a random interval in the

middle, which we call middle-censoring. This happens in clinical trials and lifetime studies

where a subject is temporarily absent or withdrawn from the study and the event of interest

occurs during this period, so that the exact time of occurrence cannot be observed. This is also

applicable in cases where some of the observations are so imprecise that they are stated as

intervals, as for example the situation where peoples’ willingness to pay for a natural

resource. In this talk, we present a “self-consistent estimator” and the Nonparametric MLE

for the survival function, study its large-sample properties, and demonstrate how well it works

even in the presence of heavy censoring. Presence of covariates can also be dealt with both in

a parametric and semi-parametric set-up.

Everyone is welcome




Title : Linear spaces and preservers of bounded rank two per-symmetric triangular matrices Speaker : Associate Prof. Dr. Chooi Wai Leong Institute of Mathematical Sciences University of Malaya

Date : 29 September 2014 (Monday) Time : 10:00 am – 11:00 am Venue : MM3, Institute of Mathematical Sciences

Abstract

Let be a field and nm, be integers .3 Let )(nSM and )(nST denote

respectively the linear space of nn per-symmetric matrices over and the linear

space of nn per-symmetric triangular matrices over . In this talk, the structure of

linear subspaces of bounded rank two matrices of )(nST will be given. Using this

structural result, a classification of bounded rank two linear preservers

),()(: mn SMST with of characteristic not two, is obtained.

Everyone is welcome




Title : Geometry of Per-alternate Triangular Matrices Speaker : Dr. Kwa Kiam Heong Institute of Mathematical Sciences University of Malaya

Date : 29 September 2014 (Monday) Time : 11:00 am – 12:00 pm Venue : MM3, Institute of Mathematical Sciences

Abstract

In this talk, we study bijective adjacency invariant maps on per-alternate upper

triangular matrices over an arbitrary field. Contrary to those on full matrices, it is

found that such maps not only carry rank-2 matrices to rank-2 matrices, but may also

fix all rank-2 matrices.

Everyone is welcome




Title : Synchronization of New Fractional Order Chaotic System Speaker : Prof. Dr. P. BALASUBRAMANIAM Registrar and Professor of Mathematics Gandhigram Rural Institute - Deemed University Gandhigram-624302 Tamilnadu, INDIA Date : 03 – 12 – 2014 (Wednesday) Time : 3.00 PM – 4.00 PM Venue : MM3, Institute of Mathematical Sciences

Abstract

In this presentation, synchronization of a class of fractional order systems is analyzed

since in recent days, chaos control and synchronization of fractional order systems have

attracted many researchers due to its potential applications in secure communication;

signal processing; encryption and decryption; electronic circuits and so on. To validate the

obtained theoretical result, numerical simulation is provided along with description of

construction novel key agreement protocol.

Everyone is welcome

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