Analysis and Selection of a Remote Docking Simulation Visual Display System

The development of a remote docking simulation visual display system is examined. Video system and operator performance are discussed as well as operator command and control requirements and a design analysis of the reconfigurable work station

Reply to "Comment on `Resilience of gated avalanche photodiodes against bright illumination attacks in quantum cryptography'"

This is a Reply to the Comment by Lydersen et al. [arXiv: 1106.3756v1]

Developing reading comprehension with moving image narratives

This paper reports the findings from a small-scale exploratory study that investigated how moving-image narratives might enable children to develop transferable reading comprehension strategies. Using short, animated, narrative films, 28 primary-aged children engaged in a 10-week programme that included the explicit instruction of comprehension strategies in small group settings. Baseline and final data relating to children's reading accuracy, rate and comprehension of written texts were gathered using a standardised reading assessment. Findings show that children’s reading comprehension scores showed significant improvement after the programme. Furthermore, reading accuracy scores also improved beyond expected levels even though no decoding of written words had occurred in the programme. While further research is needed, these findings offer a challenge to models of reading that potentially over-simplify the complex relationship between the word recognition and comprehension. More importantly, the findings point at the importance of using alternatives to written texts within the reading curriculum.This research was sponsored in part by Film Club (www.filmclub.org) and also supported by a Cambridge Humanities Small Research Grant.This is the author accepted manuscript. The final version is available from Taylor & Francis at http://dx.doi.org/10.1080/0305764X.2014.99862

Control Software for Piezo Stepping Actuators

A control system has been developed for the Space Interferometer Mission (SIM) piezo stepping actuator. Piezo stepping actuators are novel because they offer extreme dynamic range (centimeter stroke with nanometer resolution) with power, thermal, mass, and volume advantages over existing motorized actuation technology. These advantages come with the added benefit of greatly reduced complexity in the support electronics. The piezo stepping actuator consists of three fully redundant sets of piezoelectric transducers (PZTs), two sets of brake PZTs, and one set of extension PZTs. These PZTs are used to grasp and move a runner attached to the optic to be moved. By proper cycling of the two brake and extension PZTs, both forward and backward moves of the runner can be achieved. Each brake can be configured for either a power-on or power-off state. For SIM, the brakes and gate of the mechanism are configured in such a manner that, at the end of the step, the actuator is in a parked or power-off state. The control software uses asynchronous sampling of an optical encoder to monitor the position of the runner. These samples are timed to coincide with the end of the previous move, which may consist of a variable number of steps. This sampling technique linearizes the device by avoiding input saturation of the actuator and makes latencies of the plant vanish. The software also estimates, in real time, the scale factor of the device and a disturbance caused by cycling of the brakes. These estimates are used to actively cancel the brake disturbance. The control system also includes feedback and feedforward elements that regulate the position of the runner to a given reference position. Convergence time for smalland medium-sized reference positions (less than 200 microns) to within 10 nanometers can be achieved in under 10 seconds. Convergence times for large moves (greater than 1 millimeter) are limited by the step rate