Capacity analysis of reservation-based random access for broadband wireless access networks

Abstract—In this paper we propose a novel model for the capacity analysis on the reservation-based random multiple access system, which can be applied to the medium access control protocol of the emerging WiMAX technology. In such a wireless broadband access system, in order to support QoS, the channel time is divided into consecutive frames, where each frame consists of some consequent mini-slots for the transmission of requests, used for the bandwidth reservation, and consequent slots for the actual data packet transmission. Three main outcomes are obtained: first, the upper and lower bounds of the capacity are derived for the considered system. Second, we found through the mathematical analysis that the transmission rate of reservationbased multiple access protocol is maximized, when the ratio between the number of mini-slots and that of the slots per frame is equal to the reciprocal of the random multiple access algorithm’s transmission rate. Third, in the case of WiMAX networks with a large number of subscribers, our analysis takes into account both the capacity and the mean packet delay criteria and suggests to keep such a ratio constant and independent of application-level data traffic arrival rate

Network Theoretical Approach to Describe Epileptic Processes

Epilepsy is characterized by recurrent unprovoked seizures. Recent studies suggest that seizure generation may be caused by the abnormal activity of the entire network. This new paradigm requires new tools and methods for its study. In this sense, synchronization by linear as well as nonlinear measures are used to determine network structure and functional connectivity of neurophysiological data. Electroencephalography (EEG) data can be analyzed using each electrode’s activity as a node of the underlying cortical network. The information provided by the synchronization matrix is the basic brick upon which several lines of analysis can be performed thereafter. Detection of community structures, identification of centrality nodes, transformation of the underlying network into a simpler one, and the identification of the basic network architecture are only some of the many lines of basic works that can be done in order to characterize the epilepsy as a network disease. This chapter describes new approaches in network epilepsy, provides mathematical concepts in order to understand the complex network analyses, and reviews the advances in network analyses and its application to epilepsy research

Context-aware routing system in an indoor scenario

The main aim of this report is to develop, design and analyse a system to simulate a context-aware routing algorithm in an indoor scenario. The context-aware purpose of this project is to take advantage of the interaction of the routing system with an entity when it is relevant. From all the context entities, the spatial environment is one of the most important, and the one which more information can be taken advantage of. Benefits can be obtained from using context-awareness in many ways, which have a special interest in the Information Technologies area. The intention of this report is to create a new application using context information related to the space, to be more precise, the position of the entities within a concrete location, and its preferences. The primary target is to design a supermarket in which benefits can be obtained from the position of the customers, their preferences (concretely the shopping list) and also the location of the products, to create an intelligent and efficient supermarket for the customer (but also for the supermarket in itself) point of view. Knowing the position of the customers and the location of the products in the supermarket can be useful to draw up efficient routes that can guide the customers through the corridors to buy their products quickly, which is the main reason why the system uses a shortest path routing algorithm to find the best route from the customer to the wished product. This algorithm considers the shortest distance and also the position of the rest of the customers so the system is able to guide the customers through another path in cases where they reach congested zones in the supermarket. Bluetooth wireless technology is used to accomplish the localization and system communication task. In addition the routing algorithm is adapted to fit the requirements of the intelligent supermarket. The design and implementation of a GUI simulator written in Java that represents the designed system is the main goal of this project. This simulator serves as a tool to test the system operation offering the possibility to modify parameters such as the rate and distribution type of the arrival of customers, the number of customers, subjective criteria of congestion and speed of the simulation among other parameters. Different types of statistics and the possibility to generate files with the information of the simulation are the main outcomes of this project, besides the GUI. In addition, this information can be translated into a Matlab script using a parser designed for this purpose. Finally the results and conclusions of the system are presented, and the future lines to follow the development of this innovative project

Optimization of vehicle routing and scheduling with travel time variability - application in winter road maintenance

This study developed a mathematical model for optimizing vehicle routing and scheduling, which can be used to collect travel time information, and also to perform winter road maintenance operations (e.g., salting, plowing). The objective of this research was to minimize the total vehicle travel time to complete a given set of service tasks, subject to resource constraints (e.g., truck capacity, fleet size) and operational constraints (e.g., service time windows, service time limit). The nature of the problem is to design vehicle routes and schedules to perform the required service on predetermined road segments, which can be interpreted as an arc routing problem (ARP). By using a network transformation technique, an ARP can be transformed into a well-studied node routing problem (NRP). A set-partitioning (SP) approach was introduced to formulate the problem into an integer programming problem (I PP). To solve this problem, firstly, a number of feasible routes were generated, subject to resources and operational constraints. A genetic algorithm based heuristic was developed to improve the efficiency of generating feasible routes. Secondly, the corresponding travel time of each route was computed. Finally, the feasible routes were entered into the linear programming solver (CPL EX) to obtain final optimized results. The impact of travel time variability on vehicle routing and scheduling for transportation planning was also considered in this study. Usually in the concern of vehicle and pedestrian\u27s safety, federal, state governments and local agencies are more leaning towards using a conservative approach with constant travel time for the planning of winter roadway maintenance than an aggressive approach, which means that they would rather have a redundancy of plow trucks than a shortage. The proposed model and solution algorithm were validated with an empirical case study of 41 snow sections in the northwest area of New Jersey. Comprehensive analysis based on a deterministic travel time setting and a time-dependent travel time setting were both performed. The results show that a model that includes time dependent travel time produces better results than travel time being underestimated and being overestimated in transportation planning. In addition, a scenario-based analysis suggests that the current NJDOT operation based on given snow sector design, service routes and fleet size can be improved by the proposed model that considers time dependent travel time and the geometry of the road network to optimize vehicle routing and scheduling. In general, the benefit of better routing and scheduling design for snow plowing could be reflected in smaller minimum required fleet size and shorter total vehicle travel time. The depot location and number of service routes also have an impact on the final optimized results. This suggests that managers should consider the depot location, vehicle fleet sizing and the routing design problem simultaneously at the planning stage to minimize the total cost for snow plowing operations

Statistical characterization of cultured neural networks activity recorded via MEA

In questa tesi si sono analizzate le attività di neuroni in coltura accoppiati con un Multi-Electrode Array (MEA) a 60 canali. Le reti neurali in vitro sono influenzate da diversi fattori, come la densità di coltura, l'età e l'animale di provenienza dei neuroni. Lo scopo di questa tesi è quello di caratterizzare questa variabilità attraverso varie analisi statistiche. Utilizzando un software sviluppato in Python si sono estratte 40 misure per descrivere un ampio spettro delle attività delle cellule, come lo spiking e i network bursts. Sono state caratterizzate le distribuzioni statistiche di queste feature, ed una analisi PCA per vedere la segregazione dei dati nelle classi considerate. Sono poi state implementate una analisi con K-Means Clustering e una classificazione mediante Random Forest, per caratterizzare la separazione spontanea e mediante label dei vari tipi di misurazioni. É stato studiato anche l'effetto del sottocampionamento temporale sulle misure, determinando che anche con un quarto della serie temporale disponibile si sono potute estrarre misure significative. Un altro tipo di sottocampionamento preso in considerazione è stato quello spaziale. Anche qui le misure si sono dimostrate robuste riducendo il numero di elettrodi da cui estrarre il segnale, fino ad un minimo di 10 elettrodi. Questa analisi della robustezza alla variabilità e al sottocampionamento delle misure di attività spontanea di reti di neuroni in vitro mediante setup MEA é utile per studiare gli effetti di sostanze chimiche, stimoli elettrici o malattie sulle colture nervose

Decoder design and decoding models for joint source-network coding

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores. Universidade do Porto. Faculdade de Engenharia. 201

On the Nature of Students\u27 Digital Mathematical Performances

In this study I investigate the nature of digital mathematical performances (DMPs) produced by elementary school students (Grades 4-6). A DMP is a multimodal text/narrative (e.g., a video) in which one uses the performance arts to communicate mathematical ideas. I analyze twenty-two DMPs available at the Math + Science Performance Festival in 2008. Assuming a sociocultural/postmodern perspective with emphasis on multimodality, my focus is on the role of the arts and technology in shaping students’ mathematical communication and thinking. Methodologically, I employ qualitative case studies, along with video analysis. I conduct a descriptive analysis of each DMP using Boorstin’s (1990) categories of what makes good films, focusing on surprises, sense-making, emotions, and visceral sensations. I also conduct a cross-case analysis using Boorstin’s categories and the mathematical processes and strands of the Ontario Curriculum. The multimodal nature of DMP is one of its most significant pedagogic attributes. Mathematics is traditionally communicated through print-based texts, but the production of DMPs is an alternative that engages students in conceiving multimodal narratives. The playfulness offers scenarios for students’ collaboration, creativity, and imagination. By making DMPs available online, students share their ideas in a public and social environment, beyond the classrooms. Most of the DMPs only explore Geometry and offer opportunities to experience some surprises, sense-making, emotions, and visceral sensations. The lack of focus on other strands (e.g., Algebra) may be seen as a reflection on what (and how) students are (or not) learning in their classes. The production of conceptual DMPs is a rare event, although I acknowledge that I analyzed only DMPs of the first year of the Festival, that is, students did not have examples or references to produce their DMPs. Some DMPs potentially explore conceptual mathematical surprises, but they appear to have gaps in terms of sense-making. The use of the arts and technologies does not guarantee the mathematical conceptuality of DMPs. This study contributes to mathematics education with an exploratory discussion about how mathematical ideas can be (a) communicated and represented as multimodal texts at the elementary school level and (b) seen through a performance arts lens. The study also points out directions about the pedagogic components for conceiving conceptual DMPs in terms of the performance arts and the components of the Ontario Curriculum

Англійська загальнонаукова лексика і фразеологія

У навчальному посібнику подано лексичний мінімум, вправи та тексти, націлені на пасивне і активне засвоєння лексики і фразеології. Означена система вправ і завдання до текстів носять комунікативний характер, мають дидактичне обґрунтування і базується на останніх досягненнях методики викладання іноземних мов. Призначено для аспірантів та здобувачів усіх факультетів та фахів.Lexical and phraseological minimum, exercises and texts aimed at mastering the vocabulary both passively and actively are presented in the work. The given exercise system and comprehension tasks to the texts are made up with the focus on communication, they have didactic ground and are based on up-to-date achievements of foreign language teaching techniques. It has been developed for post-graduates and applicants of all specialities