1,972 research outputs found

    Linear or Rotary Actuator Using Electromagnetic Driven Hammer as Prime Mover

    Get PDF
    We claim a hammer driven actuator that uses the fast-motion, low-force characteristics of an electro-magnetic or similar prime mover to develop kinetic energy that can be transformed via a friction interface to produce a higher-force, lower-speed linear or rotary actuator by using a hammering process to produce a series of individual steps. Such a system can be implemented using a voice-coil, electro-mechanical solenoid or similar prime mover. Where a typical actuator provides limited range of motion or low force, the range of motion of a linear or rotary impact driven motor can be configured to provide large displacements which are not limited by the characteristic dimensions of the prime mover

    Human rights and public education

    Get PDF
    This article attempts a contrast to the contribution by Hugh Starkey. Rather than his account of the inexorable rise of human rights discourse, and of the implementation of human rights standards, human rights are here presented as always and necessarily scandalous and highly contested. First, I explain why the UK has lagged so far behind its European neighbours in implementing citizenship education. Second, a comparison with France shows that the latest UK reforms bring us up to 1789. Third, the twentieth-century second-generation social and economic rights are still anathema in the UK. Fourth, the failure to come to terms with Empire and especially the slave trade means that the UK’s attitude to third-generation rights, especially the right of peoples to self-determination, is heavily compromised. Taking into account the points I raise, citizenship education in the UK might look very different

    Preliminary performance measurements of bolometers for the Planck high-frequency instrument

    Get PDF
    We report on the characterization of bolometers fabricated at the Jet Propulsion Laboratory for the High Frequency Instrument (HFI) of the joint ESA/NASA Herschel/Planck mission to be launched in 2007. The HFI is a multicolor focal plane which consists of 48 bolometers operated at 100mK. Each bolometer is mounted to a feedhorn-filter assembly which defines one of six frequency bands centered between 100-857GHz. Four detectors in each of six bands are coupled to both linear polarizations and thus measure the total intensity. In addition, eight detectors in each of 3 bands (143, 217, and 353GHz) couple only to a single linear polarization and thus provide measurements of the Stokes parameters, Q and U, as well the total intensity. The detectors are required to achieve a Noise Equivalent Power (NEP) at or below the background limit ∌ 10^(-17)W/√Hz for the telescope and time constants of a few ms, short enough to resolve point sources as the 5 to 9 arc-minute beams move across the sky in great circles at 1 rpm. The bolometers are tested at 100mK in a commercial dilution refrigerator with a custom built thermal control system to regulate the heat sink with precision < 100nK/√Hz. The 100mK tests include dark electrical characterization of the load curves, optical and electrical measurement of the thermal time constants and measurement of the noise spectral density from 0.01 to 10Hz for up to 24 bolometers simultaneously

    A Study into the Dynamics of Three Dimensional Tape Spring Folds

    Full text link

    Analytical solution of a model for complex food webs

    Get PDF
    We investigate numerically and analytically a recently proposed model for food webs [Nature {\bf 404}, 180 (2000)] in the limit of large web sizes and sparse interaction matrices. We obtain analytical expressions for several quantities with ecological interest, in particular the probability distributions for the number of prey and the number of predators. We find that these distributions have fast-decaying exponential and Gaussian tails, respectively. We also find that our analytical expressions are robust to changes in the details of the model.Comment: 4 pages (RevTeX). Final versio

    Population Uncertainty in Model Ecosystem: Analysis by Stochastic Differential Equation

    Full text link
    Perturbation experiments are carried out by contact process and its mean-field version. Here, the mortality rate is increased or decreased suddenly. It is known that the fluctuation enhancement (FE) occurs after the perturbation, where FE means a population uncertainty. In the present paper, we develop a new theory of stochastic differential equation. The agreement between the theory and the mean-field simulation is almost perfect. This theory enables us to find much stronger FE than reported previously. We discuss the population uncertainty in the recovering process of endangered species.Comment: 16 pages, 4 figure, submitted to J. Phys. Soc. Jp

    Ethical and compliance-competence evaluation: a key element of sound corporate governance

    Get PDF
    Motivated by the ongoing post-Enron refocusing on corporate governance and the shift by the Financial Services Authority (FSA) in the UK to promoting compliance- competence within the financial services sector, this paper demonstrates how template analysis can be used as a tool for evaluating compliance-competence. Focusing on the ethical dimension of compliance-competence, we illustrate how this can be subjectively appraised. We propose that this evaluation technique could be utilised as a starting point in informing senior management of corporate governance issues and be used to monitor and demonstrate key compliance and ethical aspects of an institution to external stakeholders and regulators
    • 

    corecore