New Solutions for the Planetary Dynamics in HD160691 using a Newtonian Model and Latest Data

In this letter we present several new three and four-planet solutions based on the most current available radial velocity data for HD160691 ($\mu$Ara). These solutions are optimised using the Planetary Orbit Fitting Process (POFP) which is programmed and executed in MATLAB. POFP is based on a full integration of the system's multiple-body Newtonian equations of motion and on a multi level optimisation utilizing a variety of algorithms. The POFP solutions are presented in the context of the Keplerian-based solutions already appearing in the literature which we have reproduced here for comparison. The different solutions and their properties are compared over all data sets separately and combined. The new solutions do not seem to exhibit instabilities and are both co-planar and three-dimensional. We also provide a comparative prediction of the published and new solutions showing their diversion in the near future. In the short term, this projection will allow to choose between the variety of solutions as further observations are made.Comment: Letter, accepted by MNRAS Feb 200

Stabilization of grid frequency through dynamic demand control

Frequency stability in electricity networks is essential to the maintenance of supply quality and security. This paper investigates whether a degree of built-in frequency stability could be provided by incorporating dynamic demand control into certain consumer appliances. Such devices would monitor system frequency (a universally available indicator of supply-demand imbalance) and switch the appliance on or off accordingly, striking a compromise between the needs of the appliance and the grid. A simplified computer model of a power grid was created incorporating aggregate generator inertia, governor action and load-frequency dependence plus refrigerators with dynamic demand controllers. Simulation modelling studies were carried out to investigate the system's response to a sudden loss of generation, and to fluctuating wind power. The studies indicated a significant delay in frequency-fall and a reduced dependence on rapidly deployable backup generation

Cryptanalyzing a discrete-time chaos synchronization secure communication system

This paper describes the security weakness of a recently proposed secure communication method based on discrete-time chaos synchronization. We show that the security is compromised even without precise knowledge of the chaotic system used. We also make many suggestions to improve its security in future versions.Comment: 11 pages, 3 figures, latex forma

Automated reduction of instantaneous flow field images

An automated data reduction system for the analysis of interference fringe patterns obtained using the particle image velocimetry technique is described. This system is based on digital image processing techniques that have provided the flexibility and speed needed to obtain more complete automation of the data reduction process. As approached here, this process includes scanning/searching for data on the photographic record, recognition of fringe patterns of sufficient quality, and, finally, analysis of these fringes to determine a local measure of the velocity magnitude and direction. The fringe analysis as well as the fringe image recognition are based on full frame autocorrelation techniques using parallel processing capabilities

Noise-Induced Linearisation and Delinearisation

It is demonstrated, by means of analogue electronic simulation and theoretically, that external noise can markedly change the character of the response of a nonlinear system to a low-frequency periodic field. In general, noise of sufficient intensity {\it linearises} the response. For certain parameter ranges in particular cases, however, an increase in the noise intensity can sometime have the opposite effect and is shown to {\it delinearise} the response. The physical origins of these contrary behaviours are discussed.Comment: 17 pages. No special macros. Figures on reques

A medium-rise 1970s maternity hospital in the east of England: Resilience and adaptation to climate change

The late 1970s design for the Rosie Maternity Hospital on the Addenbrookes campus in Cambridge is a recurring type across the UK National Health Service, a framed three-storey courtyard configuration in brick masonry. It was selected as a case study project for the ‘Design and Delivery of Robust Hospitals in a Changing Climate’ project, pursuing the methodology developed for that research. Temperature data were collected in representative spaces within the hospital, over a two-year period. These revealed overheating in mild conditions relative to an observed 24℃ threshold for sleep but concealed within the customary 28℃ threshold marking the upper limit of acceptable conditions. The building was modelled using current climate data to predict 2010 conditions. The model was then calibrated against the observed 2010 data and used to predict the likely internal temperatures in current and 2030s. The results indicated an increase in peak temperatures. Four adaptive intervention schemes were subsequently developed: an ‘enlightened’ industry standard ‘Passivhaus’-type option providing superinsulation, sealed glazing and heat recovery; a lower technology-based scheme promoting natural cross-ventilation by providing greater opening glazing area, opening up the plan, sunshading and additional insulation; an enhanced natural ventilation scheme glazing over the courtyards to provide supply air winter gardens, and an advanced natural ventilation option pursuing passive downdraught cooling. All four schemes were modelled using the projected current and 2030s weather data and their performance was compared. The schemes were fully costed to yield relative ‘value for money’ guidance to National Health Service Trusts. Practical application: The Heat wave Plan for England 2014 warns National Health Service (NHS) organisations of the risks to patients, particularly the very young, the elderly and the seriously ill, from extreme summer heat events.1 The Chief Medical Officer in her introduction challenges each NHS locality to plan well in advance of hot spells, as appropriate. This paper describes the likely extent of overheating risk and a series of potential adaptation plans for a recurring NHS hospital building type. As a consequence, estates and facilities decision makers in NHS organisations and Public Health England officers charged with the mitigation of risk resulting from overheating of wards and clinical spaces will benefit directly in their necessary decision making from the findings. Policy makers in the Department of Health and policy advisors in the NHS Sustainable Development Unit and the Climate Change Committee Adaptation Sub-Committee will benefit from the evidence presented in advising the NHS and Department of Health. This work was undertaken at part of the UK Engineering and Physical Sciences Research Council project, ‘Design and Delivery of Robust Hospital Environments in a Changing Climate’ [grant number EP/G061327/1] through the ‘Adaptation and Resilience to a Changing Climate’ (ARCC) programme under the auspices of the ‘Living with Environmental Change’ (LWEC) initiative. The Project also received funding directly from the Department of Health.This is the final version. It was first published by Sage at http://bse.sagepub.com/content/early/2015/01/30/0143624414567544

Electrode level Monte Carlo model of radiation damage effects on astronomical CCDs

Current optical space telescopes rely upon silicon Charge Coupled Devices (CCDs) to detect and image the incoming photons. The performance of a CCD detector depends on its ability to transfer electrons through the silicon efficiently, so that the signal from every pixel may be read out through a single amplifier. This process of electron transfer is highly susceptible to the effects of solar proton damage (or non-ionizing radiation damage). This is because charged particles passing through the CCD displace silicon atoms, introducing energy levels into the semi-conductor bandgap which act as localized electron traps. The reduction in Charge Transfer Efficiency (CTE) leads to signal loss and image smearing. The European Space Agency's astrometric Gaia mission will make extensive use of CCDs to create the most complete and accurate stereoscopic map to date of the Milky Way. In the context of the Gaia mission CTE is referred to with the complementary quantity Charge Transfer Inefficiency (CTI = 1-CTE). CTI is an extremely important issue that threatens Gaia's performances. We present here a detailed Monte Carlo model which has been developed to simulate the operation of a damaged CCD at the pixel electrode level. This model implements a new approach to both the charge density distribution within a pixel and the charge capture and release probabilities, which allows the reproduction of CTI effects on a variety of measurements for a large signal level range in particular for signals of the order of a few electrons. A running version of the model as well as a brief documentation and a few examples are readily available at http://www.strw.leidenuniv.nl/~prodhomme/cemga.php as part of the CEMGA java package (CTI Effects Models for Gaia).Comment: Accepted by MNRAS on 13 February 2011. 15 pages, 7 figures and 5 table

Tuning the Performance of a Computational Persistent Homology Package

In recent years, persistent homology has become an attractive method for data analysis. It captures topological features, such as connected components, holes, and voids from point cloud data and summarizes the way in which these features appear and disappear in a filtration sequence. In this project, we focus on improving the performanceof Eirene, a computational package for persistent homology. Eirene is a 5000-line open-source software library implemented in the dynamic programming language Julia. We use the Julia profiling tools to identify performance bottlenecks and develop novel methods to manage them, including the parallelization of some time-consuming functions on multicore/manycore hardware. Empirical results show that performance can be greatly improved