Search results for "imulation"
showing 10 items of 7271 documents
Interference Estimation in IEEE 802.11 Networks
2010
This article describes a technique for distinguishing and quantifying medium access control (MAC) and physical layer (PHY) interference in error-prone 802.11 networks. This technique, is fully distributed, allowing each station to estimate interference individually. The estimator is based on an extended Kalman filter coupled to a mechanism for revealing abrupt changes in state. The network state is a vector of two components, representing PHY interference, expressed in terms of channel-error rate, and MAC interference. Two distinct state models are considered. When PHY interference can be assumed to be constant for all stations, network congestion is expressed by the number of competing ter…
An Integrated Framework for Meta Modeling
2006
Meta modeling is an essential means to systematize, formalize, standardize, integrate, analyze and compare models, techniques, methods and tools. Numerous fields, such as databases, software engineering, software architectures, semantic web, computer-aided tools and method engineering, have benefited from it. The importance of meta modeling is ever increasing along with the emergence of novel approaches, architectures, techniques and languages based on UML and MDA. This paper presents a framework to integrate and compare divergent conceptions of meta modeling in databases, software engineering, and information systems development. The framework is applied to analyze and compare conceptions …
Hybrid descriptive-inferential method for key feature selection in prostate cancer radiomics
2021
In healthcare industry 4.0, a big role is played by radiomics. Radiomics concerns the extraction and analysis of quantitative information not visible to the naked eye, even by expert operators, from biomedical images. Radiomics involves the management of digital images as data matrices, with the aim of extracting a number of morphological and predictive variables, named features, using automatic or semi-automatic methods. Multidisciplinary methods as machine learning and deep learning are fully involved in this field. However, the large number of features requires efficient and effective core methods for their selection, in order to avoid bias or misinterpretations problems. In this work, t…
A measurement-based trajectory model for drifted motions towards a target zone
2016
Trajectory models have numerous applications in the area of wiewlwss communications. The aim of this paper is to develop an empirical trajectory model for drifted motions. Recently, a highly flexible trajectory model based on the primitives of Brownian fields (TramBrown) was proposed by A. Borhani and M. Patzold. This paper provides an empirical proof for TramBrown using global positioning system (GPS) data collected from real life user traces drifting to a particular target point or a zone. The recorded location coordinates of the mobile user are processed to compute the total travelling length and the angle-of-motion (AOM) along the drifted trajectory. It is shown that the probability den…
The dynamics over the next few years of the Spanish mobile telecommunications market share: a mathematical modelling approach
2013
Taking into account available data from 2002 to 2009 about the market share percentages of the Spanish mobile telecommunications service providers, a dynamic diffusion model to study the evolution of the clients’ change between the different companies during the period 2010–2016 is proposed. The constructed model provides a tool for forecasting short-term trends about the customers’ preferences with respect to mobile network operators taking into account both, autonomous decisions due to direct marketing and advertising strategies, and also decisions adopted through interaction via social influence. The model can provide insights to companies for designing strategies in order to gain market…
Probabilistic models for the fatigue resistance of welded steel joints subjected to constant amplitude loading
2022
Abstract S-N curves found in various rules and regulations are the basic tool for the practicing engineer when carrying out life predictions for welded details in dynamically loaded structures. The present work is investigating the expected fatigue life and associated scatter for welded steel joints subjected to Constant Amplitude (CA) loading. The objective is to obtain more reliable life predictions based on advancements in the probabilistic model fitted to collected life data. A Random Fatigue Limit Model (RFLM) is proposed to obtain fatigue resistance curves at given probability levels of survival. As a distinction to more conventional statistical methods, the model is treating both the…
The Effect of Medium-Intensity Electromagnetic Stimulation on Pelvic Floor Muscle Activity in a Young Woman—A Case Report
2021
Aims In recent years, devices for deep electromagnetic stimulation have been implemented in clinical practice. These devices generate pulses with a frequency of 1 to 50 Hz and magnetic induction of up to 2.5 T. Due to the possibility of producing or an effective deep-penetrating mechanical vibration, electromagnetic stimulation is increasingly used in the physiotherapy of urogynecological disorders. This study aimed to analyse of the effect of deep electromagnetic stimulation on the bioelectrical activity of pelvic floor muscles in a young woman. Case report The case of a 24-year-old woman with no diagnosed stress urinary incontinence is presented. The subject underwent electromagnetic stim…
A Bayesian Learning Automata-Based Distributed Channel Selection Scheme for Cognitive Radio Networks
2014
We consider a scenario where multiple Secondary Users SUs operate within a Cognitive Radio Network CRN which involves a set of channels, where each channel is associated with a Primary User PU. We investigate two channel access strategies for SU transmissions. In the first strategy, the SUs will send a packet directly without operating Carrier Sensing Medium Access/Collision Avoidance CSMA/CA whenever a PU is absent in the selected channel. In the second strategy, the SUs implement CSMA/CA to further reduce the probability of collisions among co-channel SUs. For each strategy, the channel selection problem is formulated and demonstrated to be a so-called "Potential" game, and a Bayesian Lea…
A Rule-Based Method to Model Myocardial Fiber Orientation for Simulating Ventricular Outflow Tract Arrhythmias
2017
Comunicació presentada a: FIMH 2017 9th International Conference, celebrada a Toronto, Canadà, de l'11 al 13 de juny de 2017. Myocardial fiber orientation determines the propagation of electrical waves in the heart and the contraction of cardiac tissue. One common approach for assigning fiber orientation to cardiac anatomi- cal models are Rule-Based Methods (RBM). However, RBM have been developed to assimilate data mostly from the Left Ventricle. In conse- quence, fiber information from RBM does not match with histological data in other areas of the heart, having a negative impact in cardiac simulations beyond the LV. In this work, we present a RBM where fiber orientation is separately mode…
P–446 Controlled ovarian stimulation protocols for oocyte vitrification induce differential gene expression profiles in primary tumours of breast can…
2021
Abstract Study question Could controlled ovarian stimulation (COS) protocols used in fertility preservation (FP) impact on malignant cell proliferation and tumour molecular profiling of breast cancer (BC) patients? Summary answer Letrozole supplementation during ovarian stimulation for oocyte vitrification could be considered as a safe procedure in estrogen-dependent BC patients undergoing FP. What is known already High estradiol levels associated to COS could promote changes in gene expression in estrogen-positive BC tumors. Estradiol levels reached during the ovarian stimulation could aggressively promote malignant cell proliferation and cell migration to adjacent organs. Aromatase inhibi…