Temporal evolution of the "thermal" and "superthermal" income classes in the USA during 1983-2001

Personal income distribution in the USA has a well-defined two-class structure. The majority of population (97-99%) belongs to the lower class characterized by the exponential Boltzmann-Gibbs ("thermal") distribution, whereas the upper class (1-3% of population) has a Pareto power-law ("superthermal") distribution. By analyzing income data for 1983-2001, we show that the "thermal" part is stationary in time, save for a gradual increase of the effective temperature, whereas the "superthermal" tail swells and shrinks following the stock market. We discuss the concept of equilibrium inequality in a society, based on the principle of maximal entropy, and quantitatively show that it applies to the majority of population.Comment: v.3: 7 pages, 5 figures, EPL style, more references adde

Exponential distribution of financial returns at mesoscopic time lags: a new stylized fact

We study the probability distribution of stock returns at mesoscopic time lags (return horizons) ranging from about an hour to about a month. While at shorter microscopic time lags the distribution has power-law tails, for mesoscopic times the bulk of the distribution (more than 99% of the probability) follows an exponential law. The slope of the exponential function is determined by the variance of returns, which increases proportionally to the time lag. At longer times, the exponential law continuously evolves into Gaussian distribution. The exponential-to-Gaussian crossover is well described by the analytical solution of the Heston model with stochastic volatility.Comment: 7 pages, 12 plots, elsart.cls, submitted to the Proceedings of APFA-4. V.2: updated reference

Development of Prometeu autonomous robot for ball handling in Eurobot

Eurobot is a robotics European challenge for the young generation (university and technical schools) which is held annually, with a different challenge in every edition, and participate around about 200 teams every year. Each game comprises two teams competing against each other and does not allow draws. This work describes the design, development and building up of an autonomous mobile robot to fulfill this challenge. This paper includes the challenge description, robot design, sensors used, the strategy used and some conclusion. The team that built this robot and participated on Eurobot is made up of 4 industrial electronic undergraduate students from University of Minho

Optimization of fast moving robots and implementation of I2C protocol to control electronic devices

This paper briefly describes the main changes in the robots from Minho Team since the last RoboCup. Work has been carried out on the robots in order to constantly improve their capabilities, based on the experiences from previous participations. The main topics to deal in this paper are related with the I2C new communications protocol recently implemented in the robots, a description of the whole electronics system based on a new diagram which contains all the devices used in the robots, the inclusion of new faster motors, a description of the robot game play strategy, some operating system remarks which are related to some requirements of our actual system, and the main conclusions related to the work carried out so far. The use of the I2C protocol forced the team to change all the electronic boards and these were completely redesigned in-house, tested and implemented on the robots.Fundação para a Ciência e a Tecnologia (FCT) - POSI/ROBO/43892/200

New improvements of MINHO Team for RoboCup middle size league in 2003

Although this research group has started a robotic football team in 1998, MINHO team has been participating in RoboCup only since 1999. The robots were completely developed by the undergraduate team members (mechanics, hardware and software), due to budget reasons, and every year new improvements had been made. The team came to a point where new improvements would mean complete changes in the robot design, hardware and mechanics. Therefore, this year major changes have been implemented. Being all member of an Industrial Electronics department, our main research areas consist of general electronics, computer vision/image processing, and control. In this paper, the major changes implemented are described and some results assessed