Meta-Communication and Market Dynamics. Reflexive Interactions of Financial Markets and the Mass Media

A widely held belief in financial economics suggests that stock prices always adequately reflect all available information. Price movements away from fundamentals are assumed to occur only infrequently, if at all. „False“ prices are supposed to be corrected by the counter-actions of „rational“ investors reestablishing equilibrium. However, empirical evidence of widespread irrationality among investors as well as theoretical insights into the properties of complex systems suggest that this view is too static. In fact, it can be shown that under certain conditions dynamic disequilibria have a considerable probability of being „locked in“. The mass media play no mean role in this: By conditioning trend-following behavior and fostering coordination among large numbers of investors, the media can help bring about such destabilizing moves. Media attention can induce positive feedback by increasing the level of excess noise in the market while decreasing the number of perceived behavioral options. Meta-communication thus generated is a prime source of instability in financial markets.

Computing Dynamic Output Feedback Laws

The pole placement problem asks to find laws to feed the output of a plant governed by a linear system of differential equations back to the input of the plant so that the resulting closed-loop system has a desired set of eigenvalues. Converting this problem into a question of enumerative geometry, efficient numerical homotopy algorithms to solve this problem for general Multi-Input-Multi-Output (MIMO) systems have been proposed recently. While dynamic feedback laws offer a wider range of use, the realization of the output of the numerical homotopies as a machine to control the plant in the time domain has not been addressed before. In this paper we present symbolic-numeric algorithms to turn the solution to the question of enumerative geometry into a useful control feedback machine. We report on numerical experiments with our publicly available software and illustrate its application on various control problems from the literature.Comment: 20 pages, 3 figures; the software described in this paper is publicly available via http://www.math.uic.edu/~jan/download.htm

Encoderless Gimbal Calibration of Dynamic Multi-Camera Clusters

Dynamic Camera Clusters (DCCs) are multi-camera systems where one or more cameras are mounted on actuated mechanisms such as a gimbal. Existing methods for DCC calibration rely on joint angle measurements to resolve the time-varying transformation between the dynamic and static camera. This information is usually provided by motor encoders, however, joint angle measurements are not always readily available on off-the-shelf mechanisms. In this paper, we present an encoderless approach for DCC calibration which simultaneously estimates the kinematic parameters of the transformation chain as well as the unknown joint angles. We also demonstrate the integration of an encoderless gimbal mechanism with a state-of-the art VIO algorithm, and show the extensions required in order to perform simultaneous online estimation of the joint angles and vehicle localization state. The proposed calibration approach is validated both in simulation and on a physical DCC composed of a 2-DOF gimbal mounted on a UAV. Finally, we show the experimental results of the calibrated mechanism integrated into the OKVIS VIO package, and demonstrate successful online joint angle estimation while maintaining localization accuracy that is comparable to a standard static multi-camera configuration.Comment: ICRA 201

Two-handed navigation in a haptic virtual environment

This paper describes the initial results from a study looking at a two-handed interaction paradigm for tactile navigation for blind and visually impaired users. Participants were set the task of navigating a virtual maze environment using their dominant hand to move the cursor, while receiving contextual information in the form of tactile cues presented to their non-dominant hand. Results suggest that most participants were comfortable with the two-handed style of interaction even with little training. Two sets of contextual cues were examined with information presented through static patterns or tactile flow of raised pins. The initial results of this study suggest that while both sets of cues were usable, participants performed significantly better and faster with the static cues

Teaching practical science online using GIS: a cautionary tale of coping strategies

Strong demand for GIS and burgeoning cohorts have encouraged the delivery of GIS teaching via online distance education models. This contribution reviews a brief foray (2012–2014) into this field by the Open University, deploying open source GIS software to enable students to perform practical science investigations online. The “Remote observation” topic spanned four science disciplines in 6 weeks – an ambitious remit within an innovative overarching module. Documenting the challenges and strategies involved, this paper uses forum usage and student feedback data to derive insights into the student experience and the pitfalls and pleasures of teaching GIS at a distance

An FPGA Architecture and CAD Flow Supporting Dynamically Controlled Power Gating

© 2015 IEEE.Leakage power is an important component of the total power consumption in field-programmable gate arrays (FPGAs) built using 90-nm and smaller technology nodes. Power gating was shown to be effective at reducing the leakage power. Previous techniques focus on turning OFF unused FPGA resources at configuration time; the benefit of this approach depends on resource utilization. In this paper, we present an FPGA architecture that enables dynamically controlled power gating, in which FPGA resources can be selectively powered down at run-time. This could lead to significant overall energy savings for applications having modules with long idle times. We also present a CAD flow that can be used to map applications to the proposed architecture. We study the area and power tradeoffs by varying the different FPGA architecture parameters and power gating granularity. The proposed CAD flow is used to map a set of benchmark circuits that have multiple power-gated modules to the proposed architecture. Power savings of up to 83% are achievable for these circuits. Finally, we study a control system of a robot that is used in endoscopy. Using the proposed architecture combined with clock gating results in up to 19% energy savings in this application

An Energy Efficient Semi-static Power Control and Link Adaptation Scheme in UMTS HSDPA

High speed downlink packet access (HSDPA) has been successfully applied in commercial systems and improves user experience significantly. However, it incurs substantial energy consumption. In this paper, we address this issue by proposing a novel energy efficient semi-static power control and link adaptation scheme in HSDPA. Through estimating the EE under different modulation and coding schemes (MCSs) and corresponding transmit power, the proposed scheme can determine the most energy efficient MCS level and transmit power at the Node B. And then the Node B configure the optimal MCS level and transmit power. In order to decrease the signaling overhead caused by the configuration, a dual trigger mechanism is employed. After that, we extend the proposed scheme to the multiple input multiple output (MIMO) scenarios. Simulation results confirm the significant EE improvement of our proposed scheme. Finally, we give a discussion on the potential EE gain and challenge of the energy efficient mode switching between single input multiple output (SIMO) and MIMO configuration in HSDPA.Comment: 9 pages, 11 figures, accepted in EURASIP Journal on Wireless Communications and Networking, special issue on Green Radi