Chimera states in small disordered optomechanical arrays

Synchronization of weakly-coupled non-linear oscillators is a ubiquitous phenomenon that has been observed across the natural sciences. We study the dynamics of optomechanical arrays - networks of mechanically compliant structures that interact with the radiation pressure force - which are driven to self-oscillation. These systems offer a convenient platform to study synchronization phenomena and have potential technological applications. We demonstrate that this system supports the existence of long-lived chimera states, where parts of the array synchronize whilst others do not. Through a combined numerical and analytical analysis we show that these chimera states can only emerge in the presence of disorder.Comment: 4+ pages, 4 figures, comments very welcome

Wireless Communication in Fire Sport

Tato práce se zabývá návrhem bezdrátové časomíry pro disciplíny požárního sportu. Cílem je nahradit dlouhé kabelové rozvody bezdrátovými spoji při zachování srovnatelné, nebo lepší spolehlivosti. S tím souvisí potřeba synchronizovat hodiny mezi jednotlivými bezdrátovými moduly. Důležitou částí práce je proto návrh a implementace vhodného synchronizačního algoritmu a komunikačního protokolu. Navržený systém byl realizován formou prototypu na vývojové platformě Texas Instruments LaunchPad EXP430FR4133 s využitím bezdrátových modulů s čipem Texas Instruments CC1101. Parametry navrženého systému časomíry (zejména přesnost synchronizace a měření) byly ověřeny v laboratorních podmínkách.This work describes the design of wireless timer for fire sport disciplines. Its aim is to replace long wires with wireless communication while preserving equal or better reliability. Important part is the need for clock synchronization between wireless modules. Related topic is selection of suitable synchronization algorithm and communication protocol. The proposed system was realized in form of prototype using Texas Instruments's development platform LaunchPad EXP 430 FR4133 and wireless modules with Texas Instruments's chip CC1101. Parameters of designed system (especially the accuracy of time synchronization and measurement) were verified in laboratory.

Welche Berufsorientierung suchen Jugendliche?

Kommunen und Kreise haben die Berufsorientierung als wichtiges Handlungsfeld bei der Unterstützung erfolgreicher Übergänge von Jugendlichen in die Arbeitswelt entdeckt. Angesichts einer Vielzahl von Angeboten und beteiligten Akteuren kommen aber Fragen nach Übersicht, Abstimmung und Wirkung auf. Die Sozialforschungsstelle Dortmund (sfs) hat in den Jahren 2009 und 2010 in Forschungs- und Gestaltungsprojekten für die Kreise Herford und Gütersloh die Perspektiven von Jugendlichen auf die Angebote der Berufsorientierung erhoben. Der Beitrag fasst die Ergebnisse zweier Erhebungen zusammen und schlägt einen Phasenplan vor, der eine Systematisierung von regionalen Berufsorientierungsangeboten entlang der Bedarfe von Jugendlichen leiten kann. Die Auswahlkriterien, nach denen Jugendliche Angebote bewerten, werden in diesen Phasenplan einbezogen

MODELING OF MASS LOSS OF CHAR PARTICLES DURING COMBUSTION AND INTERACTION WITH INERT MATERIAL

The inspiration for this research was the numerical simulation of mass loss of char particles during its combustion in a CFB boiler. The mass loss was presented as the superposition of two separate processes i.e. combustion and surface erosion. The values obtained by the model and experimental data show a good level of conformity

RELATIONSHIP BETWEEN MUSCLE ARCHITECTURE AND CONCENTRIC MOVEMENT VELOCITY DURING RESISTANCE EXERCISE

We compared muscle architecture with concentric movement velocity (CMV) during resistance exercise (RE). Twenty-four RE active males (21.4 ± 1.8 yrs) completed a dominant leg, single-leg leg extension at 75 & 90% of 1-repetition maximum (1RM) to failure. Ultrasound measures of the vastus lateralis (VL) were taken to assess pennation angle (PA), muscle thickness (MT) & fascicle length (FL). MT & 1RM were moderately correlated (r=0.32). Further, PA & FL were significantly correlated with 75% 1RM peak (P) & average (Av) CMV, (r=0.41-0.75) & FL/MT was strongly correlated with 75% 1RM P & Av CMV (r=0.64-0.76). Additionally, multiple regression suggested PA & FL were significantly associated with CMV. The data suggest FL, PA & FL/MT are importantly related to CMV during moderate-to-heavy RE, to failure

Extended Surface of Materials as a Result of Chemical Equilibrium

A system consisting of at least two components was considered. In this system, nanocrystalline material is formed at high temperature, at which diffusion does not limit the mass transport. The structure results from establishing an equilibrium between surface and volume of the crystallites and their surroundings in isothermal-adiabatic conditions. The surface of each crystallite is covered with another substance. On the basis of the performed energy-balance calculations it was concluded that the reduction in the surface area is associated with a decrease in the surface coverage degree and thus with the necessity to provide energy to the system in order to remove chemisorbed atoms. An increase in the temperature of a nanocrystalline substance to a temperature higher than the preparation temperature results in the formation of a new state of equilibrium. At temperatures below the maximum temperature only the equilibrium between the gas phase and the surface exists