41,708 research outputs found
A co-operating solver approach to building simulation
This paper describes the co-operating solver approach to building simulation as encapsulated within the ESP-r system. Possible adaptations are then considered to accommodate new functional requirements
Development of a contra-rotating tidal current turbine and analysis of performance
A contra-rotating marine current turbine has a number of attractive features: nearzero reactive torque on the support structure, near-zero swirl in the wake, and high relative inter-rotor rotational speeds. Modified blade element modelling theory has been used to design and predict the characteristics of such a turbine, and a model turbine and test rig have been constructed. Tests in a towing tank demonstrated the feasibility of the concept. Power coefficients were high for such a small model and in excellent agreement with predictions, confirming the accuracy of the computational modelling procedures. Highfrequency blade loading data were obtained in the course of the experiments. These show the anticipated dynamic components for a contra-rotating machine. Flow visualization of the wake verified the lack of swirl behind the turbine. A larger machine is presently under construction for sea trials
Design and testing of a contra-rotating tidal current turbine
A contra-rotating marine current turbine has a number of attractive features: nearzero reactive torque on the support structure, near-zero swirl in the wake, and high relative inter-rotor rotational speeds. Modified blade element modelling theory has been used to design and predict the characteristics of such a turbine, and a model turbine and test rig have been constructed. Tests in a towing tank demonstrated the feasibility of the concept. Power coefficients were high for such a small model and in excellent agreement with predictions, confirming the accuracy of the computational modelling procedures. High-frequency blade loading data were obtained in the course of the experiments. These show the anticipated dynamic components for a contra-rotating machine. Flow visualization of the wake verified the lack of swirl behind the turbine. A larger machine is presently under construction for sea trials
Direct to consumer advertising via the Internet, a study of hip resurfacing
With increased use of the internet for health information and direct to consumer advertising from medical companies, there is a concern about the quality of the information available for patients. The aim of this study was to examine the quality of health information on the internet for hip resurfacing. An assessment tool was designed to measure quality of information. Websites were measured on credibility of source; usability; currentness of the information; content relevance; content accuracy/completeness and disclosure/bias. Each website assessed was given a total score, based on number of scores achieved from the above categories websites were further analysed on author, geographical origin and possession of an independent credibility check. There was positive correlation between the overall score for the website and the score of each website in each assessment category. Websites by implant companies, doctors and hospitals scored poorly. Websites with an independent credibility check such as Health on the Net (HoN) scored twice the total scores of websites without. Like other internet health websites, the quality of information on hip resurfacing websites is variable. This study highlights methods by which to assess the quality of health information on the internet and advocates that patients should look for a statement of an "independent credibility check" when searching for information on hip resurfacing
Nonlocal hydrodynamic influence on the dynamic contact angle: Slip models versus experiment
Experiments reported by Blake et al. [Phys. Fluids. 11, 1995 (1999)] suggest that the dynamic contact angle formed between the free surface of a liquid and a moving solid boundary at a fixed contact-line speed depends on the flow field/geometry near the moving contact line. The present paper examines quantitatively whether or not it is possible to attribute this effect to bending of the free surface due to hydrodynamic stresses acting upon it and hence interpret the results in terms of the so-called ``apparent'' contact angle. It is shown that this is not the case. Numerical analysis of the problem demonstrates that, at the spatial
resolution reported in the experiments, the variations of the ``apparent'' contact angle (defined in two different ways) caused by variations in the flow field, at a fixed contact-line speed, are too small to account for the observed effect. The results clearly indicate that the actual (macroscopic) dynamic contact angle, i.e.\ the one used in fluid mechanics as a boundary condition for the equation determining the free surface shape, must be regarded as dependent not only on the contact-line speed but also on the flow field/geometry in the vicinity of the moving contact line
Influence of Charge and Energy Imbalances on the Tunneling Current through a Superconductor-Normal Metal Junction
We consider quasiparticle charge and energy imbalances in a thin
superconductor weakly coupled with two normal-metal electrodes via tunnel
junctions at low temperatures. Charge and energy imbalances, which can be
created by injecting quasiparticles at one junction, induce excess tunneling
current at the other junction. We numerically obtain
as a function of the bias voltage across the detection junction.
We show that at the zero bias voltage is purely determined by the
charge imbalance, while the energy imbalance causes a nontrivial -dependence of . The obtained voltage-current characteristics
qualitatively agree with the experimental result by R. Yagi [Phys. Rev. B {\bf
73} (2006) 134507].Comment: 10 pages, 5 figure
Interchain coherence of coupled Luttinger liquids at all orders in perturbation theory
We analyze the problem of Luttinger liquids coupled via a single-particle
hopping \tp and introduce a systematic diagrammatic expansion in powers of
\tp. An analysis of the scaling of the diagrams at each order allows us to
determine the power-law behavior versus \tp of the interchain hopping and of
the Fermi surface warp. In particular, for strong interactions, we find that
the exponents are dominated by higher-order diagrams producing an enhanced
coherence and a failure of linear-response theory. Our results are valid at any
finite order in \tp for the self-energy.Comment: 4 pages, 3 ps figures. Accepted for publication in Phys. Rev. Let
Creating citizen-consumers? Public service reform and (un)willing selves
About the book: Postmodern theories heralded the "death of the subject", and thereby deeply contested our intuition that we are free and willing selves. In recent times, the (free) will has come under attack yet again. Findings from the neuro- and cognitive sciences claim the concept of will to be scientifically untenable, specifying that it is our brain rather than our 'self' which decides what we want to do. In spite of these challenges however, the willing self has come to take centre stage in our society: juridical and moral practices ascribing guilt, or the organization of everyday life attributing responsibilities, for instance, can hardly be understood without taking recourse to the willing subject.
In this vein, the authors address topics such as the genealogy of the concept of willing selves, the discourse on agency in neuroscience and sociology, the political debate on volition within neoliberal and neoconservative regimes, approaches toward novel forms of relational responsibility as well as moral evaluations in conceptualizing autonomy
Hyperpolarized xenon nuclear spins detected by optical atomic magnetometry
We report the use of an atomic magnetometer based on nonlinear
magneto-optical rotation with frequency modulated light (FM NMOR) to detect
nuclear magnetization of xenon gas. The magnetization of a
spin-exchange-polarized xenon sample (cm at a pressure of bar,
natural isotopic abundance, polarization 1%), prepared remotely to the
detection apparatus, is measured with an atomic sensor (which is insensitive to
the leading field of 0.45 G applied to the sample; an independent bias field at
the sensor is G). An average magnetic field of nG induced by
the xenon sample on the 10-cm diameter atomic sensor is detected with
signal-to-noise ratio , limited by residual noise in the magnetic
environment. The possibility of using modern atomic magnetometers as detectors
of nuclear magnetic resonance and in magnetic resonance imaging is discussed.
Atomic magnetometers appear to be ideally suited for emerging low-field and
remote-detection magnetic resonance applications.Comment: 4 pages, 4 figure
Absence of strong magnetic fluctuations in the iron phosphide superconductors LaFePO and Sr2ScO3FeP
We report neutron inelastic scattering measurements on polycrystalline LaFePO
and Sr2ScO3FeP, two members of the iron phosphide families of superconductors.
No evidence is found for any magnetic fluctuations in the spectrum of either
material in the energy and wavevector ranges probed. Special attention is paid
to the wavevector at which spin-density-wave-like fluctuations are seen in
other iron-based superconductors. We estimate that the magnetic signal, if
present, is at least a factor of four (Sr2ScO3FeP) or seven (LaFePO) smaller
than in the related iron arsenide and chalcogenide superconductors. These
results suggest that magnetic fluctuations are not as influential on the
electronic properties of the iron phosphide systems as they are in other
iron-based superconductors.Comment: 7 pages, 5 figure
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