Statistical mechanics of Floquet systems with regular and chaotic states

We investigate the asymptotic state of time-periodic quantum systems with regular and chaotic Floquet states weakly coupled to a heat bath. The asymptotic occupation probabilities of these two types of states follow fundamentally different distributions. Among regular states the probability decreases from the state in the center of a regular island to the outermost state by orders of magnitude, while chaotic states have almost equal probabilities. We derive an analytical expression for the occupations of regular states of kicked systems, which depends on the winding numbers of the regular tori and the parameters temperature and driving frequency. For a constant winding number within a regular island it simplifies to Boltzmann-like weights \exp(-\betaeff \Ereg_m), similar to time-independent systems. For this we introduce the regular energies \Ereg_m of the quantizing tori and an effective winding-number-dependent temperature 1/\betaeff, different from the actual bath temperature. Furthermore, the occupations of other typical Floquet states in a mixed phase space are studied, i.e. regular states on nonlinear resonances, beach states, and hierarchical states, giving rise to distinct features in the occupation distribution. Avoided crossings involving a regular state lead to drastic consequences for the entire set of occupations. We introduce a simplified rate model whose analytical solutions describe the occupations quite accurately.Comment: 18 pages, 11 figure

Return on shares of steel companies under the influence of mergers and acquisitions

The present article intends to asses returns on shares of the steel companies that were formed based on either merger or acquisition. The analysis included 14 operations in the steel industry. Attention was paid to returns of the companies performing acquisitions, as well as to the returns on shares that presented the acquisition target. The analysis was performed based on the “event study” method, and the analysed event was the announcement or notification of realization of an acquisition. Shares of the target steel companies as well as acquirers are attaining higher returns, but the change was not statistical significant.Web of Science54130630

Switching mechanism in periodically driven quantum systems with dissipation

We introduce a switching mechanism in the asymptotic occupations of quantum states induced by the combined effects of a periodic driving and a weak coupling to a heat bath. It exploits one of the ubiquitous avoided crossings in driven systems and works even if both involved Floquet states have small occupations. It is independent of the initial state and the duration of the driving. As a specific example of this general switching mechanism we show how an asymmetric double well potential can be switched between the lower and the upper well by a periodic driving that is much weaker than the asymmetry.Comment: 5 pages, 5 figure

Feasibility of NASA TT&C via Commercial Satellite Services

This report presents the results of a study to identify impact and driving requirements by implementing commercial satellite communications service into traditional National Aeronautics and Space Administration (NASA) space-ground communications. The NASA communication system is used to relay spacecraft and instrument commands, telemetry and science data. NASA's goal is to lower the cost of operation and increase the flexibility of spacecraft operations. Use of a commercial network offers the opportunity to contact a spacecraft on a nearly "on-demand" basis with ordinary phone calls to enable real time interaction with science events

Records of Clubiona alpicola in Germany and Czechia (Araneida, Clubionidae)

Die Kurzmitteilung enthält neben Fundortangaben für Clubiona alpicola auch Hinweise zu Verbreitung, Taxonomie und Systematik

Fusion of IMU and Vision for Absolute Scale Estimation in Monocular SLAM

The fusion of inertial and visual data is widely used to improve an object's pose estimation. However, this type of fusion is rarely used to estimate further unknowns in the visual framework. In this paper we present and compare two different approaches to estimate the unknown scale parameter in a monocular SLAM framework. Directly linked to the scale is the estimation of the object's absolute velocity and position in 3D. The first approach is a spline fitting task adapted from Jung and Taylor and the second is an extended Kalman filter. Both methods have been simulated offline on arbitrary camera paths to analyze their behavior and the quality of the resulting scale estimation. We then embedded an online multi rate extended Kalman filter in the Parallel Tracking and Mapping (PTAM) algorithm of Klein and Murray together with an inertial sensor. In this inertial/monocular SLAM framework, we show a real time, robust and fast converging scale estimation. Our approach does not depend on known patterns in the vision part nor a complex temporal synchronization between the visual and inertial senso

Vision Based Position Control for MAVs Using One Single Circular Landmark

This paper presents a real-time vision based algorithm for 5 degrees-of-freedom pose estimation and set-point control for a Micro Aerial Vehicle (MAV). The camera is mounted on-board a quadrotor helicopter. Camera pose estimation is based on the appearance of two concentric circles which are used as landmark. We show that that by using a calibrated camera, conic sections, and the assumption that yaw is controlled independently, it is possible to determine the six degrees-of-freedom pose of the MAV. First we show how to detect the landmark in the image frame. Then we present a geometric approach for camera pose estimation from the elliptic appearance of a circle in perspective projection. Using this information we are able to determine the pose of the vehicle. Finally, given a set point in the image frame we are able to control the quadrotor such that the feature appears in the respective target position. The performance of the proposed method is presented through experimental result

Intuitive 3D Maps for MAV Terrain Exploration and Obstacle Avoidance

Recent development showed that Micro Aerial Vehicles (MAVs) are nowadays capable of autonomously take off at one point and land at another using only one single camera as exteroceptive sensor. During the flight and landing phase the MAV and user have, however, little knowledge about the whole terrain and potential obstacles. In this paper we show a new solution for a real-time dense 3D terrain reconstruction. This can be used for efficient unmanned MAV terrain exploration and yields a solid base for standard autonomous obstacle avoidance algorithms and path planners. Our approach is based on a textured 3D mesh on sparse 3D point features of the scene. We use the same feature points to localize and control the vehicle in the 3D space as we do for building the 3D terrain reconstruction mesh. This enables us to reconstruct the terrain without significant additional cost and thus in real-time. Experiments show that the MAV is easily guided through an unknown, GPS denied environment. Obstacles are recognized in the iteratively built 3D terrain reconstruction and are thus well avoide

Behavioral and neurophysiological effects of morphological awareness training on spelling and reading

Behavioral and neurophysiological effects of a computer-aided morphological training protocol were examined in German-speaking children from Grades 3 to 9. Study 1 compared morphological awareness, reading, and spelling skills of 34 trained children with an untrained control group of 34 children matched for age, sex, and intelligence. All participants in the training group showed increases in morphological awareness, but only students from secondary school improved significantly in reading and spelling competences. In Study 2, a subsample of 8 trained children with poor spelling and reading abilities and 10 untrained children with higher language competencies underwent an electroencephalography testing involving three different language tasks. The training resulted in decreased theta-activity and increased activity in lower (7-10Hz) and upper alpha (10-13Hz). These findings reflect more effortful and attention-demanding processing after the training and suggest that children with poor spelling and reading abilities use the acquired morphological knowledge in terms of a compensatory strateg