76,688 research outputs found
Random access-random release relay switching matrix
XY relay switching matrix provides complete random access and random release of 400 points. A mercury-wetted bistable relay with independent set and reset coils is the unique feature associated with each point
Inertial energy storage hardware definition study (ring rotor)
Rotor analysis, interference stresses, fabrication/assembly, failure analysis, ring tolerances, stren plots, and drawings are discussed
Mechanical capacitor
A new energy storage system (the mechanical capacitor), using a spokeless magnetically levitated composite ring rotor, is described and design formulas for sizing the components are presented. This new system is configured around a permanent magnet (flux biased) suspension which has active servo control in the radial direction and passive control in the axial direction. The storage ring is used as a moving rotor and electronic commutation of the stationary armature coils is proposed. There is no mechanical contact with the rotating spokeless ring; therefore, long life and near zero rundown losses are projected. A 7-kW h system is sized to demonstrate feasibility. A literature review of flywheel energy storage systems is also presented and general formulas are developed for comparing rotor geometries
Carbonate Formation in Non-Aqueous Environments by Solid-Gas Carbonation of Silicates
We have produced synthetic analogues of cosmic silicates using the Sol Gel
method, producing amorphous silicates of composition Mg(x)Ca(1-x)SiO3. Using
synchrotron X-ray powder diffraction on Beamline I11 at the Diamond Light
Source, together with a newly-commissioned gas cell, real-time powder
diffraction scans have been taken of a range of silicates exposed to CO2 under
non-ambient conditions. The SXPD is complemented by other techniques including
Raman and Infrared Spectroscopy and SEM imaging.Comment: 5 pages, 3 figures. Contribution to the Proceedings of the First
European Conference on Laboratory Astrophysics (ECLA
Magnetically suspended flywheel system study
A program to study the application of a graphite/epoxy, magnetically suspended, pierced disk flywheel for the combined function of spacecraft attitude control and energy storage (ACES) is described. Past achievements of the program include design and analysis computer codes for the flywheel rotor, a magnetically suspended flywheel model, and graphite/epoxy rotor rings that were successfully prestressed via interference assembly. All hardware successfully demonstrated operation of the necessary subsystems which form a complete ACES design. Areas of future work include additional rotor design research, system definition and control strategies, prototype development, and design/construction of a UM/GSFC spin test facility. The results of applying design and analysis computer codes to a magnetically suspended interference assembled rotor show specific energy densities of 42 Wh/lb (92.4 Wh/kg) are obtained for a 1.6 kWh system
Modelling energy consumption in supermarkets to reduce energy use and greenhouse gas emissions using EnergyPlus
New refrigeration system configurations and other innovating technologies in retail supermarkets need to be considered to reduce energy use and greenhouse gas emissions. In supermarkets, there is a strong interaction between the refrigerated display cases, supermarket structure, internal machinery, customers, and the store’s HVAC system. The impact of these interactions on the energy and carbon emissions of a medium sized supermarket in Paris was modelled using EnergyPlus™. The results were calibrated against a typical UK store and validated against the Paris store. The effects of applying the technologies identified to have the greatest potential to reduce carbon emissions (changing the refrigerant to R744, switching from gas to electrical heating and adding doors to chilled cabinets) were modelled. The impact of climate change on ambient temperature and the impact of changes to the grid conversion factor were predicted for the store in Paris from 2020 to 2050
Descriptions of membrane mechanics from microscopic and effective two-dimensional perspectives
Mechanics of fluid membranes may be described in terms of the concepts of
mechanical deformations and stresses, or in terms of mechanical free-energy
functions. In this paper, each of the two descriptions is developed by viewing
a membrane from two perspectives: a microscopic perspective, in which the
membrane appears as a thin layer of finite thickness and with highly
inhomogeneous material and force distributions in its transverse direction, and
an effective, two-dimensional perspective, in which the membrane is treated as
an infinitely thin surface, with effective material and mechanical properties.
A connection between these two perspectives is then established. Moreover, the
functional dependence of the variation in the mechanical free energy of the
membrane on its mechanical deformations is first studied in the microscopic
perspective. The result is then used to examine to what extent different,
effective mechanical stresses and forces can be derived from a given, effective
functional of the mechanical free energy.Comment: 37 pages, 3 figures, minor change
Crossover from Reptation to Rouse dynamics in the Cage Model
The two-dimensional cage model for polymer motion is discussed with an
emphasis on the effect of sideways motions, which cross the barriers imposed by
the lattice. Using the Density Matrix Method as a solver of the Master
Equation, the renewal time and the diffusion coefficient are calculated as a
function of the strength of the barrier crossings. A strong crossover influence
of the barrier crossings is found and it is analyzed in terms of effective
exponents for a given chain length. The crossover scaling functions and the
crossover scaling exponents are calculated.Comment: RevTeX, 11 PostScript figures include
Correlation function algebra for inhomogeneous fluids
We consider variational (density functional) models of fluids confined in
parallel-plate geometries (with walls situated in the planes z=0 and z=L
respectively) and focus on the structure of the pair correlation function
G(r_1,r_2). We show that for local variational models there exist two
non-trivial identities relating both the transverse Fourier transform G(z_\mu,
z_\nu;q) and the zeroth moment G_0(z_\mu,z_\nu) at different positions z_1, z_2
and z_3. These relations form an algebra which severely restricts the possible
form of the function G_0(z_\mu,z_\nu). For the common situations in which the
equilibrium one-body (magnetization/number density) profile m_0(z) exhibits an
odd or even reflection symmetry in the z=L/2 plane the algebra simplifies
considerably and is used to relate the correlation function to the finite-size
excess free-energy \gamma(L). We rederive non-trivial scaling expressions for
the finite-size contribution to the free-energy at bulk criticality and for
systems where large scale interfacial fluctuations are present. Extensions to
non-planar geometries are also considered.Comment: 15 pages, RevTex, 4 eps figures. To appear in J.Phys.Condens.Matte
- …