566220
Endomorphic modelling for two-dimensional time-varying autoregressive model signals
Physical signals are often non-stationary. We assume that images are non-stationary and each pixel is the output of a different set of two-dimensional autoregressive (AR) model coefficients; therefore, texture cannot be characterised by applying AR modelling techniques to the entire image. A multistage modelling technique, which appears in the literature as "endomorphic modelling", is applied to this kind of signal. The signal is divided into sub-sets of samples and each sub-set is modelled using an AR model. A new image is formed using the same AR model coefficient estimated from different blocks, then the new image is re-modelled using AR models again. This process ends when the variance of the estimated parameters is sufficiently small. The simulation results show that the variances obtained from the estimated coefficients at the second stage are much smaller than the ones from the first stage
31361010
Mammogram Analysis Using Two-Dimensional Autoregressive Models: Sufficient or Not?
Two-dimensional (2–D) autoregressive (AR) models have been used as one of the methods to characterise the textures of tumours in mammograms. Previously, the 2–D AR model coefficients were estimated for the block containing the tumour and the blocks in its 3 × 3 neighbourhood. In this paper, the possibility of having the estimated set of AR model coefficients of the block containing the tumour as a unique set of AR model coefficients for the entire mammogram is looked into. Based on the information given from the MiniMammography database, the possible number of blocks of the same size of the block containing the tumour is obtained from the entire mammogram and for each block a set of AR model coefficients is estimated using a method that combines both the Yule-Walker system of equations and the Yule-Walker system of equations in the third-order statistical domain. These sets of AR model coefficients are then compared. The simulation results show that 98.6% of the time we can not find another set of AR model coefficients representing the blocks of pixels in the possible neighbourhood of the entire mammogram for the data (95 mammograms with 5 of them having two tumours) available in the MiniMammography database.
39604886
Drug risk assessment with determining the number of sub-populations under finite mixture normal models
Abstract In some biological experiments, it is quite common that laboratory subjects may be different in their patterns of susceptibility to a treatment. In these situations, finite mixture model analysis becomes a useful tool. Under a finite mixture normal model, drug risk assessment problems are studied under the assumption that the population at risk consists of multiple sub-types of different susceptibilities. The EM algorithm and its extension are utilized to obtain the maximum likelihood estimates of the model. Particular discussion is given to the model selection problem based on Bayes factor, which is approximated by the Schwarz criterion. Meantime, the practical significance of the proposed method is illustrated with an actual dose–response data set.
122800248
Image Morphing Using Deformation Techniques
This paper presents a new image morphing method using a two-dimensional deformation technique which provides an intuitive model for a warp. The deformation technique derives aC1-continuous and one-to-one warp from a set of point pairs overlaid on two images. The resulting in-between image precisely reflects the correspondence of features specified by an animator. We also control the transition behaviour in a metamorphosis sequence by taking another deformable surface model, which is simpler and thus more efficient than the deformation technique for a warp. The proposed method separates transition control from feature interpolation and is easier to use than the previous techniques. The multigrid relaxation method is employed to solve a linear system in deriving a warp or transition rates. This method makes our image morphing technique fast enough for an interactive environment.
650244
IC-Colorings and IC-Indices of graphs
Given a coloring f:V(G)->N of graph G and any subgraph H@?G we define f"s(H)=@?"v"@?"V"("H")f(v). In particular, we denote f"s(G) by S(f). The coloring f is called an IC-coloring if for any integer k@?[1,S(f)] there is a connected subgraph H@?G such that f"s(H)=k. Also, we define the IC-index of G to beM(G)=max{S(f):f is an IC-coloring of G}.In this paper we examine some well-known classes of graphs and determine their IC-indices. In addition, several conjectures are proposed.
16950025
Distribution of path durations in mobile ad-hoc networks - Palm's Theorem to the rescue
We first study the distribution of path duration in multi-hop wireless networks. We show that as the number of hops along a path increases, the path duration distribution can be accurately approximated by an exponential distribution under a set of mild conditions, even when the link duration distributions are not identical. Then, we develop an approximate model for computing the distribution of link duration under a Random Waypoint (RWP) mobility model, and demonstrate that the path duration distribution converges to an exponential distribution with increasing number of hops. Simulation results obtained using ns-2 simulator are provided to validate the analysis.
15238266
Wireless reliable messaging protocol for Web services (WS-WRM)
By employing Web services technology, the grid system is evolving to be more manageable service infrastructure, including lifetime management, discovery of characteristics, and notifications. Reliable messaging is one of the key issues addressed for quality of services in Web services. In this paper, we propose a reliable message scheme designed for mobile environments in the context of a Web services architecture; Web services-Wireless Reliable Messaging (WS-WRM). We also consider the federation issues with emerging specifications proposed by leading Web services standard groups. We eventually intend to extend the reliability to mobile end-nodes in a more efficient way. In this paper, we address the design issues and describe the detailed scheme of messaging architecture.