Search results for "Markov model"
showing 10 items of 113 documents
The unobserved pattern of material hardship and health among older Americans
2019
This paper investigates the relationship between self-reported health and material hardship among older Americans. Differently from income-based measures, material hardship provides a more specific description of the concrete adversities faced by the elderly. We have used the last six waves of the Health and Retirement Study to explore the relative contributions of state dependence, unobserved heterogeneity and time-specific shocks on reporting poor health, experiencing food insecurity and medication cutbacks. We have used a Latent Markov model to estimate a multivariate non-linear system of equations for panel data allowing time-varying unobserved heterogeneity. Our results reveal a high s…
Uncontrolled diabetes and health care utilisation:A bivariate latent Markov model approach
2018
Although uncontrolled diabetes (UD) or poor glycaemic control is a widespread condition with potentially life-threatening consequences, there is sparse evidence of its effects on health care utilisation. We jointly model the propensities to consume health care and UD by employing an innovative bivariate latent Markov model that allows for dynamic unobserved heterogeneity, movements between latent states and the endogeneity of UD. We estimate the effects of UD on primary and secondary health care consumption using a panel dataset of rich administrative records from Spain and measure UD using a biomarker. We find that, conditional on time-varying unobservables, UD does not have a statisticall…
Designing a multi-layer edge-computing platform for energy-efficient and delay-aware offloading in vehicular networks
2021
Abstract Vehicular networks are expected to support many time-critical services requiring huge amounts of computation resources with very low delay. However, such requirements may not be fully met by vehicle on-board devices due to their limited processing and storage capabilities. The solution provided by 5G is the application of the Multi-Access Edge Computing (MEC) paradigm, which represents a low-latency alternative to remote clouds. Accordingly, we envision a multi-layer job-offloading scheme based on three levels, i.e., the Vehicular Domain, the MEC Domain and Backhaul Network Domain. In such a view, jobs can be offloaded from the Vehicular Domain to the MEC Domain, and even further o…
Model reduction techniques for the computation of extended Markov parameterizations for generalized Langevin equations
2021
Abstract The generalized Langevin equation is a model for the motion of coarse-grained particles where dissipative forces are represented by a memory term. The numerical realization of such a model requires the implementation of a stochastic delay-differential equation and the estimation of a corresponding memory kernel. Here we develop a new approach for computing a data-driven Markov model for the motion of the particles, given equidistant samples of their velocity autocorrelation function. Our method bypasses the determination of the underlying memory kernel by representing it via up to about twenty auxiliary variables. The algorithm is based on a sophisticated variant of the Prony metho…
Frame Based Equipment Medium Access in LTE-U: Mechanism Enhancements and DTMC Modeling
2017
To address the challenge of ever-growing data rate demand and benefit from the popularity of WiFi capability in mobile phones, 3GPP is studying techniques which enable the coexistence of WiFi and LTE in the unlicensed band, known as LTEU. Two flavors of the listen before talk (LBT) principle, referred to as load based equipment (LBE) and frame based equipment (FBE), are recommended by 3GPP. In this paper, we investigate two enhanced FBE mechanisms, i.e., 1) enhanced FBE (E-FBE); and 2) backoff and idle time reduction FBE (BITR-FBE) for the purpose of improving FBE. After presenting the idea of E-FBE, we propose BITR-FBE which can further improve throughput, shorten delay and reduce energy c…
A Novel Method to Characterize User Sessions of Educational Software
2013
Abstract Software applications destined for the educational environment have a long history and have evolved side by side with the progress of technology from simple computer assisted instruction programs to sophisticated eLearning platforms. A study that we have conducted on a sample of 395 children aged 6 through 12, coming from both the rural and the urban environments, shows that an increasing number of children use computer related technologies. Given their exposure to these technologies it is imperative that the educational applications be designed in a way that takes into account the children's abilities, interests and the demands for their development. We have proposed a 5-dimension…
ℓ1-Penalized Methods in High-Dimensional Gaussian Markov Random Fields
2016
In the last 20 years, we have witnessed the dramatic development of new data acquisition technologies allowing to collect massive amount of data with relatively low cost. is new feature leads Donoho to define the twenty-first century as the century of data. A major characteristic of this modern data set is that the number of measured variables is larger than the sample size; the word high-dimensional data analysis is referred to the statistical methods developed to make inference with this new kind of data. This chapter is devoted to the study of some of the most recent ℓ1-penalized methods proposed in the literature to make sparse inference in a Gaussian Markov random field (GMRF) defined …
A Quasi-likelihood Markov model for the hardenability of steel
1992
To evaluate the hardenability of steel the Jominy test can be used. A steel bar of fixed dimensions is heated up to about 850 °C and then quenched from one end by water spray. Its hardness y is then measured at increasing distances d from this quenched end giving observations (d, y(d)), which form the Jominy curve. For each Jominy curve these observations can be fitted by descending curve μ = μ(d; η) with shape parameters η = (η 1,..., η p ) T which are assumed to vary along the alloying elements (C, Mn, Cr etc.).
Performance modeling of epidemic routing
2006
In this paper, we develop a rigorous, unified framework based on ordinary differential equations (ODEs) to study epidemic routing and its variations. These ODEs can be derived as limits of Markovian models under a natural scaling as the number of nodes increases. While an analytical study of Markovian models is quite complex and numerical solution impractical for large networks, the corresponding ODE models yield closed-form expressions for several performance metrics of interest, and a numerical solution complexity that does not increase with the number of nodes. Using this ODE approach, we investigate how resources such as buffer space and the number of copies made for a packet can be tra…
Greedy versus Dynamic Channel Aggregation Strategy in CRNs: Markov Models and Performance Evaluation
2011
Part 1: - PE-CRN 2011 Workshop; International audience; In cognitive radio networks, channel aggregation techniques which aggregate several channels together as one channel have been proposed in many MAC protocols. In this paper, we consider elastic data traffic and spectrum adaptation for channel aggregation, and propose two new strategies named as Greedy and Dynamic respectively. The performance of channel aggregation represented by these strategies is evaluated using continuous time Markov chain models. Moreover, simulation results based on various traffic distributions are utilized in order to evaluate the validity and preciseness of the mathematical models.